Dissertations / Theses on the topic 'Small animal imaging'
To see the other types of publications on this topic, follow the link: Small animal imaging.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Small animal imaging.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Evans, Eleanor. "Improved quantification in small animal PET/MR." Thesis, University of Cambridge, 2015. https://www.repository.cam.ac.uk/handle/1810/252640.
Full textAbstract:
In translational medicine, complementary functional and morphological imaging techniques are used extensively to observe physiological processes in vivo and to assess structural changes as a result of disease progression. The combination of magnetic resonance imaging (MRI) and positron emission tomography (PET) provides excellent soft tissue contrast from MRI with exceptional sensitivity and specificity from PET. This thesis explores the use of sequentially acquired PET and MR images to improve the quantification of small animal PET data. The primary focus was to improve image-based estimates of the arterial input function (AIF), which defines the amount of PET tracer within blood plasma over time. The AIF is required to produce physiological parameters quantifying key processes such as metabolism or perfusion from dynamic PET images. The gold standard for AIF measurement, however, requires serial blood sampling over the course of a PET scan, which is invasive in rat studies but prohibitive in mice due to small total blood volumes. To address this issue, the geometric transfer matrix (GTM) and recovery coefficient (RC) techniques were applied using anatomical MR images to enable the extraction of partial volume corrected image based AIFs from mouse PET images. A non-invasive AIF extraction method was also developed for rats, beginning with the optimization of an automated voxel selection algorithm to assist in extracting MR contrast agent signal time courses from dynamic susceptibility contrast (DSC) MRI data. This procedure was then combined with dynamic contrast enhanced (DCE) MRI to track a combined injection of Gadolinium-based contrast agent and PET tracer through the rat brain. By comparison with gold standard tracer blood sample data, it was found that normalized MRI-based AIFs could be successfully converted into PET tracer AIFs in the first pass phase when fitted with gamma variate functions. Finally, a MR image segmentation method used to provide PET attenuation correction in mice was validated using the Cambridge split magnet PET/MR scanner?s transmission scanning capabilities. This work recommends that contributions from MR hardware in the PET field of view must be accounted forto gain accurate estimates of tracer uptake and standard uptake values (SUVs). This thesis concludes that small animal MR data taken in the same imaging session can provide non-invasive methods to improve PET image quantification, giving added value to combined PET/MR studies over those conducted using PET alone.
2
Weisenberger, Andrew Gerard. "Gamma-ray imaging detector for small animal research." W&M ScholarWorks, 1998. https://scholarworks.wm.edu/etd/1539623944.
Full textAbstract:
A novel radiation imaging technology for in vivo molecular imaging in small mammals is described. The goal of this project is to develop a new type of imaging detector system suitable for real-time in vivo probe imaging studies in small animals. This technology takes advantage of the gamma-ray and x-ray emission properties of the radioisotope iodine 125 (125I) which is employed as the label for molecular probes. The radioisotope 125I is a gamma-ray emitting radioisotope that can be commercially obtained already attached to biomedically interesting molecules to be used as tracers for biomedical and molecular biology research.;The isotope 125I decays via electron capture consequently emitting a 35 keV gamma-ray followed by the near coincident emission of several 27--32 keV Kalpha and Kbeta shell x-rays. Because of these phenomena, a coincidence condition can be set to detect 125I thus enabling the reduction of any background radiation that could contaminate the image. The detector system is based on an array of CsI(Na) crystal scintillators coupled to a 125 mm diameter position sensitive photomultiplier tube. An additional standard 125 mm diameter photomultiplier tube coupled to a NaI(Tl) scintillator acts as the coincident detector. to achieve high resolution images the detector system utilizes a custom-built copper laminate high resolution collimator. The 125I detector system can achieve a spatial resolution of less than 2 mm FWHM for an object at a distance of 1.5 cm from the collimator. The measured total detector sensitivity while using the copper collimator was 68 cpm/muCi.;Results of in vivo mouse imaging studies of the biodistribution of iodine, melatonin, and a neurotransmitter analog (RTI-55) are presented. Many studies in molecular biology deal with following the expression and regulation of a gene at different stages of an organism's development or under different physiological conditions. This detector system makes it possible for laboratories without access to standard nuclear medicine radiopharmaceuticals to perform in vivo imaging research on small a mammals using a whole range of 125I labeled markers that are obtainable from commercial sources.
3
Larsson, Daniel. "Small-Animal Imaging with Liquid-Metal-Jet X-Ray Sources." Doctoral thesis, KTH, Biomedicinsk fysik och röntgenfysik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-163169.
Full textAbstract:
Small-animal x-ray imaging is an important tool for medical research. The penetration power of x-rays makes it possible to investigate the 3D structure of small animals and other thick biological samples by computed tomography (CT). However, small-animal x-ray imaging often requires high resolution due to the small structures involved, and short exposure times due to sample movement. This constitutes a challenge, since these two properties require compact x-ray sources with parameters that are not widely available. In this Thesis we present the first application of liquid-metal-jet sources for small-animal imaging. This source concept was invented at KTH just over ten years ago. The use of a high-speed metal jet as electron-beam target, instead of a solid anode, enables higher x-ray flux while maintaining a small x-ray spot for high-resolution imaging. In the present work, a liquid-metal jet source with a higher-energy spectrum has been developed. It has stronger 24 keV radiation compared to previous sources, which makes it more suitable for imaging of small animals and other few-cm-thick objects, which require the higher penetration of 20-35 keV x-rays. We have applied the liquid-metal-jet x-ray sources for whole-body imaging of sacrificed mice and zebrafish. With high-resolution absorption-contrast CT we have visualized fine bone details of mice. We have also used phase contrast, a new method that can considerably improve imaging of, e.g., soft tissue, for demarcation of mm-sized tumors inside a full mouse and for mouse cartilage imaging. In zebrafish imaging, we have exploited the greatly enhanced contrast of phase-imaging to resolve single muscle fibers (and possibly even myofibrils) in whole zebrafish in a laboratory setting for the first time. The muscle structures have diameters in the 5-7 μm range and extremely low contrast, which makes them difficult to observe. With phase contrast, we have demonstrated low-dose and high-resolution angiography of mouse and rat organs and tissues ex vivo. We show detection of blood vessels with diameters below 10 μm with radiation doses compatible with living small animals, which is not possible with absorption contrast and iodinated contrast agents. In addition, we have investigated the vascular network of tumors in mouse ears and visualized the chaotic arrangement of newly-formed blood vessels. Finally, we present the first results from a new high-power liquid-metal-jet x-ray source prototype, operating at 10× the power of our previous sources, with the same x-ray spot size. This source constitutes an important step towards future in-vivo small-animal laboratory imaging with high resolution.Röntgenavbildning av små försöksdjur är en viktig metod inom medicinsk forskning. Röntgenstrålar penetrerar material, vilket gör det möjligt att undersöka 3D-strukturen hos försöksdjur och andra tjocka biologiska prov med hjälp av datortomografi (CT). Tyvärr kräver smådjursavbildning ofta dels hög upplösning, eftersom de relevanta strukturerna är små, dels korta exponeringstider, eftersom objektet tenderar att röra sig. Detta är en utmaning, då båda egenskaperna kräver kompakta röntgenkällor med speciella egenskaper som inte är brett tillgängliga. I denna avhandling visar vi den första användningen av metallstråleröntgenkällor för avbildning av hela smådjur. Den här typen av röntgenkälla uppfanns vid KTH för drygt tio år sedan. Genom att låta elektronerna träffa en stråle av flytande metall, istället för en solid metallanod, kan vi generera mer röntgenstrålning men samtidigt behålla en liten källpunkt, vilket behövs för avbildning med hög upplösning. En ny metallstrålekälla utvecklades som en del av denna avhandling. Den ger ett röntgenspektrum med högre energier, vilket gör källan mer lämpad än tidigare källor för avbildning av små försöksdjur och andra centimetertjocka biologiska objekt. Vi har använt metallstrålekällor för att avbilda intakta, avlivade möss och zebrafiskar. Med högupplöst absorptions-CT har vi detekterat små bendetaljer inuti möss. Vi har även använt faskontrastavbildning, en ny metod som avsevärt kan förbättra avbildning av mjukvävnad, till att demarkera millimeterstora tumörer inuti en hel mus, samt för avbildning av brosk i leder hos möss. Faskontrast ger en kraftig förstärkning av kontrasten i bilden, vilket även har använts för att för första gången detektera individuella muskelfibrer (och eventuellt även myofibriller) inuti zebrafiskar med en kompakt röntgenkälla. Muskelstrukturerna har diametrar på 5-7 μm och låg kontrast, vilket gör dem svåra att observera. Med hjälp av faskontrast har vi utvecklat en metod för att avbilda blodkärl med diametrar under 10 μm inuti organ och vävnader från möss och råttor ex vivo, med stråldoser som är kompatibla med studier av levande smådjur. Detta är inte möjligt med konventionell absorptionskontrast och jod-baserade kontrastmedel. Vi har dessutom avbildat nyformade blodkärl kring tumörer i musöron och observerat kärlens kaotiska struktur. Slutligen presenterar vi de första resultaten från en prototyp av en ny högeffektskälla. Källan har tio gånger högre effekt än tidigare metallstrålekällor, men bibehåller samma storlek på källpunkten. Den här högeffektskällan är ett viktigt steg mot framtida laboratoriebaserad avbildning av levande små försöksdjur med hög upplösning.
QC 20150331
4
Qian, Jianguo. "A versatile imaging system for in vivo small animal research." W&M ScholarWorks, 2008. https://scholarworks.wm.edu/etd/1539623532.
Full textAbstract:
In vivo small animal imaging has become an essential technique for molecular biology studies. However, requirements of spatial resolution, sensitivity and image quality are quite challenging for the development of small-animal imaging systems. The capabilities of the system are also significant for carrying out small animal imaging in a wide range of biological studies. The goal of this dissertation is to develop a high-performance imaging system that can readily meet a wide range of requirements for a variety of small animal imaging applications. Several achievements have been made in order to fulfill this goal.;To supplement our system for parallel-hole single photon emission computed tomography (SPECT) based upon a 110 mm diameter circular detector, we have developed novel compact gamma cameras suitable for imaging an entire mouse. These gamma cameras facilitate multi-head (>2) parallel-hole SPECT with the mouse in close proximity to the detector face in order to preserve spatial resolution. Each compact gamma cameras incorporates pixellated Nal(Tl) scintillators and a pair of Hamamatsu H8500 position sensitive photomultiplier tubes (PSPMTs). Two types of copper-beryllium parallel-hole collimators have been designed. These provide high-sensitivity imaging of I-125 or excellent spatial resolution over a range of object-detector distances. Both phantom and animal studies have demonstrated that these gamma cameras perform well for planar scintigraphy and parallel-hole SPECT of mice.;To further address the resolution limitations in parallel-hole SPECT and the sensitivity and limited field of view of single-pinhole SPECT, we have developed novel multipinhole helical SPECT based upon a 110 mm diameter circular detector equipped with a pixellated Nal(Tl) scintillator array. A brass collimator has been designed and produced containing five 1 mm diameter pinholes. Results obtained in SPECT studies of various phantoms show an enlarged field of view, very good resolution and improved sensitivity using this new imaging technique.;These studies in small-animal imaging have been applied to in vivo biological studies related to human health issues including studies of the thyroid and breast cancer. A re-evaluation study of potassium iodide blocking efficiency in radioiodine uptake in mice suggests that the FDA-recommended human dose of stable potassium iodide may not be sufficient to effectively protect the thyroid from radioiodine contamination. Another recent study has demonstrated that multipinhole helical SPECT can resolve the fine structure of the mouse thyroid using a relatively low dose (200 muCi). Another preclinical study has focused on breast tumor imaging using a compact gamma camera and an endogenous reporter gene. In that ongoing study, mammary tumors are imaged at different stages. Preliminary results indicate different functional patterns in the uptake of radiotracers and their potential relationship with other tumor parameters such as tumor size.;In summary, we have developed a versatile imaging system suitable for in vivo small animal research as evidenced by a variety of applications. The modular construction of this system will allow expansion and further development as new needs and new opportunities arise.
5
Terrin, Massimo. "Micro-CT for small animal imaging : Optimization of the tube voltage for low-contrast imaging." Thesis, KTH, Skolan för teknik och hälsa (STH), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-176482.
Full textAbstract:
This master thesis evaluated the optimal tube voltage for low-contrast imaging of a micro-CT system (intended for small animal imaging) built at the School of Technology and Health (STH) of the Royal Institute of Technology (KTH). The main goal of this work was to calibrate the above-mentioned device (composed moreover by a Hamamatsu microfocus L10951-01 X-ray tube, a CMOS flat panel Hamamatsu C7942CA-22 and using a Cone-Beam CT reconstruction algorithm) for obtaining the best imaging of low-contrast structures. In order to do this, an analytical model, re-adapted from the previous state-of-the-art Micro-CT studies, was evaluated for finding a sub-optimal tube voltage from which to start the experiments, done on a reference Low-Contrast phantom specifically intended for the calibration of Micro-CT devices. Finally, by looking to the results from the experiments, a good tube setting for the optimization of the CT for low-contrast imaging was found. The optimal tube voltage for low-contrast imaging, from the experiments on the QRM phantom, was found to be between 48 and 50 kV. This tube voltage values gave the best CNR and contrast profiles results. Ultimately, we found that the usage of a 1mm Al filtration reduced the absorbed dose without affecting the image quality.
6
Manivannan, Niranchana. "Use of Multiple Imaging Views for Improving Image Quality in Small Animal MR Imaging Studies." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1436753010.
Full text
7
Daibes, Figueroa Said. "Discrete NaI(TI) crystal detector optimization for small animal SPECT molecular imaging." Diss., Columbia, Mo. : University of Missouri-Columbia, 2005. http://hdl.handle.net/10355/5821.
Full textAbstract:
Thesis (Ph.D.)--University of Missouri-Columbia, 2005.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (November 15, 2006) Vita. Includes bibliographical references.
8
Kujala, Naresh Gandhi Yu Ping. "Frequency domain fluorescent molecular tomography and molecular probes for small animal imaging." Diss., Columbia, Mo. : University of Missouri--Columbia, 2009. http://hdl.handle.net/10355/7021.
Full textAbstract:
Title from PDF of title page (University of Missouri--Columbia, viewed on Feb 26, 2010). The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Dissertation advisor: Dr. Ping Yu. Vita. Includes bibliographical references.
9
Cooper, Reynold James. "Performance of the SmartPET Positron Emission Tomography System for Small Animal Imaging." Thesis, University of Liverpool, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.491374.
Full textAbstract:
The experimental results presented in this study demonstrate the performance of a prototype Positron Emission Tomography system utilising planar HPGe detector technology. The experimental measurements undertaken provide evidence of the feasibility of such a system for small animal imaging. It has been shown how the use of digital Pulse Shape Analysis techniques may be employed in order to improve the achievable image quality. By performing high precision scans of one the SmartPET HPGe detectors with finely collimated gamma-ray beams at a range of energies the performance and response of the detector as a function of gamma-ray interaction position has been quantified. This analysis has facilitated the development of parametric Pulse Shape Analysis techniques and algorithms for the correction of imperfections in detector response. These algorithms have then been applied to data from PET imaging measurements using both SmartPET detectors in conjunction with the specially designed rotating gantry. A number of point sources have been imaged and it has been shown how, when using simple PSA approaches, the nature of an event has direct implications for the quality of the resulting image. Over 60% of coincident events from 511keV gamma rays have been processed in imaging these point sources, increasing the imaging sensitivity by a factor of three in comparison to previous work. The absolute detection sensitivity of the SmartPET system has been found to be 0.99%. The SmartPET system has been used to image distributed sources for the first time. A 22Na line source was imaged in a number of different orientations and reconstructed with a spatial resolution approaching the fundamental limitations imposed by gamma-ray non-colinearity and positron range blurring. Increasingly complex source distributions have been imaged, demonstrating the ability of the system to resolve multiple features with fine spatial resolution. These measurements then allowed the current limitations of the system to be identified. Supplied by The British Library - 'The world's knowledge'
10
Valastyán, Iván. "Software Solutions for Nuclear Imaging Systems in Cardiology, Small Animal Research and Education." Doctoral thesis, KTH, Medicinsk teknik, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-12069.
Full textAbstract:
The sensitivity for observing physiological processes makes nuclear imaging an important tool in medical diagnostics. Different types of nuclear imaging modalities, with emphasis on the software components and image reconstructions, are presented in this thesis: the Cardiotom for myocardial heart studies at the Karolinska University Hospital, the small animal Positron Emission Tomograph (PET) scanners for research and the SPECT, PET, spiral CT and Cardiotom demonstrators for the Royal Institute of Technology medical imaging laboratory. A modular and unified software platform has been developed for data representation, acquisition, visualization, reconstruction and presentation of the programs of the imaging devices mentioned above. The high performance 3D ML-EM and OS-EM iterative image reconstruction methods are implemented both on Cardiotom and miniPET scanners. As a result, the in-slice resolution of the first two prototypes of the Cardiotom today is the same as the formerly used filtered back-projection, however the in-depth resolution is considerably increased. Another improvement due to the new software is the shorter time that is required for data acquisition and image reconstruction. The new electronics with the newly developed software ensure images for medical diagnosis within 10 minutes from the start ofthe examination. The first system from the standardized production of the Cardiotom cameras is in the test phase. The performance parameters (sensitivity, spatial and energy resolution, coincidence time resolution) of the full ring mini PET camera are comparable to other small animal PETsystems.QC20100721
11
Citro, Lucas Abraham. "High-field Cardiac Magnetic Resonance Imaging in Small Animal Models of Cardiovascular Disease." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1365082830.
Full text
12
Rasmussen, John C. "Development of a radiative transport based, fluorescence-enhanced, frequency-domain small animal imaging system." Thesis, [College Station, Tex. : Texas A&M University, 2006. http://hdl.handle.net/1969.1/ETD-TAMU-1067.
Full text
13
Ambrosini, Valentina <1975>. "Pre-clinical imaging: small animal pet and CT applications in pneumology, oncology and cardiology." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2008. http://amsdottorato.unibo.it/1087/.
Full text
14
Konik, Arda Bekir. "Evaluation of attenuation and scatter correction requirements in small animal PET and SPECT imaging." Diss., University of Iowa, 2010. https://ir.uiowa.edu/etd/691.
Full textAbstract:
Positron emission tomography (PET) and single photon emission tomography (SPECT) are two nuclear emission-imaging modalities that rely on the detection of high-energy photons emitted from radiotracers administered to the subject. The majority of these photons are attenuated (absorbed or scattered) in the body, resulting in count losses or deviations from true detection, which in turn degrades the accuracy of images. In clinical emission tomography, sophisticated correction methods are often required employing additional x-ray CT or radionuclide transmission scans. Having proven their potential in both clinical and research areas, both PET and SPECT are being adapted for small animal imaging. However, despite the growing interest in small animal emission tomography, little scientific information exists about the accuracy of these correction methods on smaller size objects, and what level of correction is required.
The purpose of this work is to determine the role of attenuation and scatter corrections as a function of object size through simulations. The simulations were performed using Interactive Data Language (IDL) and a Monte Carlo based package, Geant4 application for emission tomography (GATE). In IDL simulations, PET and SPECT data acquisition were modeled in the presence of attenuation. A mathematical emission and attenuation phantom approximating a thorax slice and slices from real PET/CT data were scaled to 5 different sizes (i.e., human, dog, rabbit, rat and mouse). The simulated emission data collected from these objects were reconstructed. The reconstructed images, with and without attenuation correction, were compared to the ideal (i.e., non-attenuated) reconstruction. Next, using GATE, scatter fraction values (the ratio of the scatter counts to the total counts) of PET and SPECT scanners were measured for various sizes of NEMA (cylindrical phantoms representing small animals and human), MOBY (realistic mouse/rat model) and XCAT (realistic human model) digital phantoms. In addition, PET projection files for different sizes of MOBY phantoms were reconstructed in 6 different conditions including attenuation and scatter corrections. Selected regions were analyzed for these different reconstruction conditions and object sizes. Finally, real mouse data from the real version of the same small animal PET scanner we modeled in our simulations were analyzed for similar reconstruction conditions.
Both our IDL and GATE simulations showed that, for small animal PET and SPECT, even the smallest size objects (~2 cm diameter) showed ~15% error when both attenuation and scatter were not corrected. However, a simple attenuation correction using a uniform attenuation map and object boundary obtained from emission data significantly reduces this error (~1% for smallest size and ~6% for largest size, in non-lung regions). In addition, we did not observe any significant improvement between the uses of uniform or actual attenuation map (e.g., only ~0.5% for largest size in PET studies). The scatter correction was not significant for smaller size objects, but became increasingly important for larger sizes objects.
These results suggest that for all mouse sizes and most rat sizes, uniform attenuation correction can be performed using emission data only. For smaller sizes up to ~ 4 cm, scatter correction is not required even in lung regions. For larger sizes if accurate quantization needed, additional transmission scan may be required to estimate an accurate attenuation map for both attenuation and scatter corrections.
15
Hesterman, Jacob Yost. "The Multi-Module, Multi-Resolution SPECT System: A Tool for Variable-Pinhole, Small-Animal Imaging." Diss., The University of Arizona, 2007. http://hdl.handle.net/10150/196056.
Full textAbstract:
The multi-module, multi-resolution SPECT system (M3R) was developed and evaluated at the University of Arizona's Center for Gamma-Ray Imaging (CGRI). The system consists of four modular gamma cameras stationed around a Cerrobend shielding assembly. Slots machined into the shielding allow for the easy interchange of pinhole apertures, providing M3R with excellent hardware flexibility. Motivation for the system included serving as a prototype for a tabletop, small-animal SPECT system, acting as a testbed for image quality by enabling the experimental validation of imaging theory, and aiding in the development of techniques for the emerging field of adaptive SPECT imaging.Development of the system included design and construction of the shielding assembly and pinhole apertures. The issue of pinhole design and evaluation represents a recurring theme of the presented work. Existing calibration methods were adapted for use with M3R. A new algorithm, the contracting grid-search algorithm, that is capable of being executed in hardware was developed for use in position estimation. The algorithm was successfully applied in software and progress was made in hardware implementation. Special equipment and interpolation techniques were also developed to deal with M3R unique system design and calibration requirements. A code library was created to simplify the many image processing steps required to realize successful analysis of measured image and calibration data and to achieve reconstruction.Observer studies were performed using both projection data and reconstructed images. These observer studies sought to explore signal-detection and activity estimation for various pinhole apertures. Special attention was paid to object variability, including the development and statistical analysis of a phantom capable of generating multiple realizations of a random, textured background. The results of these studies indicate potential for multiple-pinhole, multiplexed apertures but reemphasize the need for careful design and implementation of such complicated imaging elements. Several other techniques were investigated for the evaluation of pinhole apertures. These techniques are less quantitative than rigorous objective methods but offer rapid insight into an aperture's resolution, artifact, and sensitivity characteristics and may find use as predictors of observer performance for certain tasks or in the rapid aperture assessment necessary for successful adaptive SPECT imaging.
16
Trumbull, Tara. "Simulation and Analysis of an Adaptive SPECT Imaging System for Tumor Estimation." Thesis, The University of Arizona, 2011. http://hdl.handle.net/10150/144580.
Full textAbstract:
We have developed a simulation of the AdaptiSPECT small-animal Single Photon Emission Computed Tomography (SPECT) imaging system. The simulation system is entitled SimAdaptiSPECT and is written in C, NVIDIA CUDA, and Matlab. Using this simulation, we have accomplished an analysis of the Scanning Linear Estimation (SLE) technique for estimating tumor parameters, and calculated sensitivity information for AdaptiSPECT configurations.SimAdaptiSPECT takes, as input, simulated mouse phantoms (generated by MOBY) contained in binary files and AdaptiSPECT configuration geometry contained in ASCII text files. SimAdaptiSPECT utilizes GPU parallel processing to simulate AdaptiSPECT images. SimAdaptiSPECT also utilizes GPU parallel processing to perform 3-D image reconstruction from 2-D AdaptiSPECT camera images (real or simulated), using a novel variant of the Ordered Subsets Expectation Maximization (OSEM) algorithm. Methods for generating the inputs, such as a population of randomly varying numerical mouse phantoms with randomly varying hepatic lesions, are also discussed.
17
Akinyi, Teckla G. "An Affordable Open-Source Small Animal MR and Hyperpolarized Gas Compatible Ventilator: Feasibility in preclinical imaging." University of Cincinnati / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1490354672385997.
Full text
18
Vandervoort, Eric. "Improving attenuation corrections obtained using singles-mode transmission data in small-animal PET." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/608.
Full textAbstract:
The images in positron emission tomography (PET) represent three dimensional dynamic distributions of biologically interesting molecules labelled with positron emitting radionuclides (radiotracers). Spatial localisation of the radio-tracers is achieved by detecting in coincidence two collinear photons which are emitted when the positron annihilates with an ordinary electron. In order to obtain quantitatively accurate images in PET, it is necessary to correct for the effects of photon attenuation within the subject being imaged. These corrections can be obtained using singles-mode photon transmission scanning. Although suitable for small animal PET, these scans are subject to high amounts of contamination from scattered photons. Currently, no accurate correction exists to account for scatter in these data. The primary purpose of this work was to implement and validate an analytical scatter correction for PET transmission scanning. In order to isolate the effects of scatter, we developed a simulation tool which was validated using experimental transmission data. We then presented an analytical scatter correction for singles-mode transmission data in PET. We compared our scatter correction data with the previously validated simulation data for uniform and non-uniform phantoms and for two different transmission source radionuclides. Our scatter calculation correctly predicted the contribution from scattered photons to the simulated data for all phantoms and both transmission sources. We then applied our scatter correction as part of an iterative reconstruction algorithm for simulated and experimental PET transmission data for uniform and non-uniform phantoms. We also tested our reconstruction and scatter correction procedure using transmission data for several animal studies (mice, rats and primates). For all studies considered, we found that the average reconstructed linear attenuation coefficients for water or soft-tissue regions of interest agreed with expected values to within 4%. Using a 2.2 GHz processor, the scatter correction required between 6 to 27 minutes of CPU time (without any code optimisation) depending on the phantom size and source used. This extra calculation time does not seem unreasonable considering that, without scatter corrections, errors in the reconstructed attenuation coefficients were between 18 to 45% depending on the phantom size and transmission source used.
19
Kwon, Sun Kuk. "Dynamic fluorescence imaging with molecular agents for cancer detection." [College Station, Tex. : Texas A&M University, 2006. http://hdl.handle.net/1969.1/ETD-TAMU-1064.
Full text
20
Roy, Debashish. "3D Cryo-Imaging System For Whole Mouse." Case Western Reserve University School of Graduate Studies / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=case1259006676.
Full text
21
Şensoy, Levent. "Geo-Pet : a novel generic Organ-Pet for small animal organs and tissues." Diss., University of Iowa, 2016. https://ir.uiowa.edu/etd/3186.
Full textAbstract:
Reconstructed tomographic image resolution of small animal PET imaging systems is improving with advances in radiation detector development. However the trend towards higher resolution systems has come with an increase in price and system complexity. Recent developments in the area of solid-state photomultiplication devices like silicon photomultiplier arrays (SPMA) are creating opportunities for new high performance tools for PET scanner design.
Imaging of excised small animal organs and tissues has been used as part of post-mortem studies in order to gain detailed, high-resolution anatomical information on sacrificed animals. However, this kind of ex-vivo specimen imaging has largely been limited to ultra-high resolution μCT. The inherent limitations to PET resolution have, to date, excluded PET imaging from these ex-vivo imaging studies.
In this work, we leverage the diminishing physical size of current generation SPMA designs to create a very small, simple, and high-resolution prototype detector system targeting ex-vivo tomographic imaging of small animal organs and tissues.
We investigate sensitivity, spatial resolution, and the reconstructed image quality of a prototype small animal PET scanner designed specifically for imaging of excised murine tissue and organs. We aim to demonstrate that a cost-effective silicon photomultiplier (SiPM) array based design with thin crystals (2 mm) to minimize depth of interaction errors might be able to achieve sub-millimeter resolution. We hypothesize that the substantial decrease in sensitivity associated with the thin crystals can be compensated for with increased solid angle detection, longer acquisitions, higher activity and wider acceptance energy windows (due to minimal scatter from excised organs).
The constructed system has a functional field of view (FoV) of 40 mm diameter, which is adequate for most small animal specimen studies. We perform both analytical (3D-FBP) and iterative (ML-EM) methods in order to reconstruct tomographic images. Results demonstrate good agreement between the simulation and the prototype. Our detector system with pixelated crystals is able to separate small objects as close as 1.25 mm apart, whereas spatial resolution converges to the theoretical limit of 1.6 mm (half the size of the smallest detecting element), which is to comparable to the spatial resolution of the existing commercial small animal PET systems. Better system spatial resolution is achievable with new generation SiPM detector boards with 1 mm x 1 mm cell dimensions.
We demonstrate through Monte Carlo simulations that it is possible to achieve sub-millimeter spatial image resolution (0.7 mm for our scanner) in complex objects using monolithic crystals and exploiting the light-sharing mechanism among the neighboring detector cells. Results also suggest that scanner (or object) rotation minimizes artifacts arising from poor angular sampling, which is even more significant in smaller PET designs as the gaps between the sensitive regions of the detector have a more exaggerated effect on the overall reconstructed image quality when the design is more compact. Sensitivity of the system, on the other hand, can be doubled by adding two additional detector heads resulting in a, fully closed, 4π geometry.
22
Tapfer, Arne [Verfasser], Franz [Akademischer Betreuer] Pfeiffer, and Axel [Akademischer Betreuer] Haase. "Small Animal X-ray Phase-Contrast Imaging / Arne Tapfer. Gutachter: Axel Haase ; Franz Pfeiffer. Betreuer: Franz Pfeiffer." München : Universitätsbibliothek der TU München, 2013. http://d-nb.info/104227701X/34.
Full text
23
Attarwala, Ali Asgar [Verfasser], and Frederik [Akademischer Betreuer] Wenz. "Development and evaluation of quantitative imaging for improved estimation of radiopharmaceutical bio-distribution in small animal imaging / Ali Asgar Attarwala ; Betreuer: Frederik Wenz." Heidelberg : Universitätsbibliothek Heidelberg, 2017. http://d-nb.info/1177688883/34.
Full text
24
Edjlali, Ehsan. "Fluorescence diffuse optical tomographic iterative image reconstruction for small animal molecular imaging with continuous-wave near infrared light." Thèse, Université de Sherbrooke, 2017. http://hdl.handle.net/11143/10673.
Full textAbstract:
L’approximation par harmoniques sphériques (SPN) simplifiées de l’équation de transfert
radiatif a été proposée comme un modèle fiable de propagation de la lumière dans les tissus
biologiques. Cependant, peu de solutions analytiques ont été trouvées pour ce modèle. De
telles solutions analytiques sont d’une grande valeur pour valider les solutions numériques
des équations SPN, auxquelles il faut recourir dans le cas de tissus avec des géométries
courbes complexes. Dans la première partie de cette thèse, des solutions analytiques pour
deux géométries courbes sont présentées pour la première fois, à savoir pour la sphère et
pour le cylindre. Pour les deux solutions, les conditions aux frontières générales tenant
compte du saut d’indice de réfraction à l’interface du tissus et de son milieu environnant,
telles qu’applicables à l’optique biomédicale, sont utilisées. Ces solutions sont validées à
l’aide de simulations Monte Carlo basées sur un maillage de discrétisation du milieu. Ainsi,
ces solutions permettent de valider rapidement un code numérique, par exemple utilisant
les différences finies ou les éléments finis, sans nécessiter de longues simulations Monte
Carlo. Dans la deuxième partie de cette thèse, la reconstruction itérative pour l’imagerie
par tomographie optique diffuse par fluorescence est proposée sur la base d’une fonction
objective et de son terme de régularisation de type Lq-Lp. Pour résoudre le problème inverse
d’imagerie, la discrétisation du modèle de propagation de la lumière est effectuée
en utilisant la méthode des différences finies. La reconstruction est effectuée sur un modèle
de souris numérique en utilisant un maillage multi-échelle. Le problème inverse est
résolu itérativement en utilisant une méthode d’optimisation. Pour cela, le gradient de la
fonction de coût par rapport à la carte de concentration de l’agent fluorescent est nécessaire.
Ce gradient est calculé à l’aide d’une méthode adjointe. Des mesures quantitatives
utilisées en l’imagerie médicale sont utilisées pour évaluer la performance de l’approche
de reconstruction dans différentes conditions. L’approche Lq-Lp montre des performances
quantifiées élevées par rapport aux algorithmes traditionnels basés sur des fonction coût
de type somme de carrés de différences.Abstract : The simplified spherical harmonics (SPN) approximation to the radiative transfer equation has been proposed as a reliable model of light propagation in biological tissues. However, few analytical solutions have been found for this model. Such analytical solutions are of great value to validate numerical solutions of the SPN equations, which must be resorted to when dealing with media with complex curved geometries. In the first part of this thesis, analytical solutions for two curved geometries are presented for the first time, namely for the sphere and for the cylinder. For both solutions, the general refractiveindex mismatch boundary conditions, as applicable in biomedical optics, are resorted to. These solutions are validated using mesh-based Monte Carlo simulations. So validated, these solutions allow in turn to rapidly validate numerical code, based for example on finite differences or on finite elements, without requiring lengthy Monte Carlo simulations. provide reliable tool for validating numerical simulations. In the second part, iterative reconstruction for fluorescence diffuse optical tomography imaging is proposed based on an Lq-Lp framework for formulating an objective function and its regularization term. To solve the imaging inverse problem, the discretization of the light propagation model is performed using the finite difference method. The framework is used along with a multigrid mesh on a digital mouse model. The inverse problem is solved iteratively using an optimization method. For this, the gradient of the cost function with respect to the fluorescent agent’s concentration map is necessary. This is calculated using an adjoint method. Quantitative metrics resorted to in medical imaging are used to evaluate the performance of the framework under different conditions. The results obtained support this new approach based on an Lq-Lp formulation of cost functions in order to solve the inverse fluorescence problem with high quantified performance.
25
Pesnel, Sabrina. "Développement de modalités d'imagerie in vivo pour l'oncologie expérimentale." Phd thesis, Université d'Orléans, 2010. http://tel.archives-ouvertes.fr/tel-00597262.
Full textAbstract:
L'imagerie in vivo du petit animal est de plus en plus utilisée en pharmacologie pour identifier et caractériser l'activité de nouveaux agents anticancéreux.La première partie de ma thèse a consisté à développer des outils pour améliorer la quantification enbioluminescence. Une méthode, basée sur les caractéristiques spectrales des photons émis, a été établie pour corriger l'absorption tissulaire. La seconde, faisant appel aux méthodes de restauration d'images, avait pour but de corriger la diffusion pour augmenter la résolution. Dans un second temps, j'ai mis en place des modèles in vivo de tumeurs expérimentales bioluminescentes (un glioblastome intracérébral, un lymphome anaplasique à grandes cellules et un neuroblastome métastatique) en utilisant les méthodes d'imagerie décrites précédemment. Ces études ont permis d'étendre la caractérisation de l'activité préclinique d'un nouvel agent anticancéreux. L'objectif de la dernière partie de mon travail était de développer des sondes d'imagerie. La première sonde, un anticorps monoclonal anti-CD45 marqué avec un fluorochrome a permis la détection de cellules leucémiques humaines implantées chez la souris en utilisant l'imagerie de fluorescence. La seconde a été développée pour prédire l'entrée d'un agent anticancéreux, un conjugué spermine-podophyllotoxin, dans les cellules tumorales via les transporteurs des polyamines. La sonde synthétisée est une spermine à laquelle un groupement HYNIC a été ajouté afin de pouvoir lier un radioisotope : le Technétium 99m et ainsi réaliser un examen scintigraphique. Les résultats ont démontré la faisabilité d'une application préclinique de cette sonde. Ainsi à l'issu de cette thèse, les méthodes de traitement des signaux de bioluminescence développées sont disponibles pour améliorer l'application de l'imagerie optique en pharmacologie. Bien sûr des études supplémentaires sont encore nécessaires pour définir précisément dans quel contexte ces corrections seront les plus appropriées.
26
Foudray, Angela Marie Klohs. "Design of an advanced positron emission tomography detector system and algorithms for imaging small animal models of human disease." Diss., [La Jolla, Calif.] : University of California, San Diego, 2009. http://wwwlib.umi.com/cr/ucsd/fullcit?p3344655.
Full textAbstract:
Thesis (Ph. D.)--University of California, San Diego, 2009.Title from first page of PDF file (viewed March 19, 2009). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 404-423).
27
Choi, Woo Jhon. "Structural and functional imaging of the human and small animal eyes using ultrahigh speed Fourier domain optical coherence tomography." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/93058.
Full textAbstract:
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2014.Cataloged from PDF version of thesis.
Includes bibliographical references.
Optical coherence tomography (OCT) is a non-invasive optical imaging technique that allows the three-dimensional structure of biological tissue to be visualized with micrometer resolution. In ophthalmology OCT has the unique advantage that it provides cross-sectional images of the retina and choroid noninvasively and in vivo, which have led OCT to be a clinical standard for the diagnosis of a variety of retinal diseases. Although current commercial Fourier domain OCT systems have high imaging speeds of 20-100kHz A-scan rates, these imaging speeds are not sufficient for more advanced structural and functional imaging techniques. Current state-of-the-art spectral domain and swept source OCT provide ultrahigh imaging speeds of >200kHz A-scan rates. These speeds enable functional imaging of retinal blood flow, OCT angiography of the retinal and choroidal microvasculature, and wide field volumetric structural imaging of the retina and choroid. In this thesis, advances in structural and functional ophthalmic imaging techniques for the human and small animal eyes are investigated using ultrahigh speed Fourier domain OCT. The following topics are discussed: (1) a method for numerically extracting and compensating dispersion mismatch in ultrahigh resolution spectral domain OCT, (2) ultrahigh speed spectral domain imaging in the small animal eye for measuring total retinal blood flow, (3) development of ultrahigh speed phase stable swept source OCT system for human retinal imaging, (4) OCT angiography of the choriocapillaris in the human eye, (5) clinical applications of OCT angiography in retinal diseases, including diabetic retinopathy and age-related macular degeneration, (6) small animal anesthesia protocol for functional hemodynamic imaging, and (7) imaging of neurovascular coupling in small animals using ultrahigh speed OCT.
by Woo Jhon Choi.
Ph. D.
28
Ma, Rui Verfasser], Vasilis [Akademischer Betreuer] Ntziachristos, and Thorsten [Akademischer Betreuer] [Hugel. "Development of multispectral optoacoustic imaging for high resolution small animal visualization / Rui Ma. Gutachter: Thorsten Hugel ; Vasilis Ntziachristos. Betreuer: Vasilis Ntziachristos." München : Universitätsbibliothek der TU München, 2012. http://d-nb.info/1031075488/34.
Full text
29
Akkoul, Smaïl. "Filtrage et déconvolution en imagerie de bioluminescence chez le petit animal." Phd thesis, Université d'Orléans, 2010. http://tel.archives-ouvertes.fr/tel-00585392.
Full textAbstract:
Cette thèse est consacrée au traitement d'images de bioluminescence chez le petit animal. Ce type d'imagerie, bien qu'utilisé en routine pour la recherche en cancérologie par exemple, présente néanmoins des problèmes liés aux phénomènes de diffusion et d'absorption par les tissus internes à l'animal. Il s'ajoute à cela le bruit du système d'acquisition ainsi que le bruit lié aux rayonnements cosmiques. Ceci influe sur la qualité des images acquises et rend leur exploitation délicate. Le but de cette thèse est de compenser ces effets perturbateurs. Les travaux menés ont abouti à la proposition d'un modèle de formation des images de bioluminescence ainsi qu'à une chaîne de traitement adaptée composée d'une étape de filtrage suivie d'une étape de déconvolution. Après étude de la nature des différents bruits liés à l'acquisition, nous avons mis au point un nouveau filtre médian pour la suppression du bruit impulsionnel aléatoire présent sur les images acquises ; ce filtre représente le premier bloc de la chaîne proposée. Pour l'étape de déconvolution, nous avons mené une étude comparative de différents algorithmes de déconvolution. Cela a conduit à choisir un algorithme de déconvolution aveugle initialisé avec la réponse impulsionnelle estimée du système d'acquisition. Nous avons validé notre approche globale en comparant les résultats à la réalité terrain. Au travers de différents essais cliniques, nous avons montré que le traitement que nous proposons permet une amélioration significative de la mesure des sources bioluminescentes et une meilleure distinction de sources très proches, ce qui représente un apport non négligeable pour les utilisateurs d'images de bioluminescence.
30
Di, Sopra Lorenzo. "Geometric Misalignment Calibration and Detector Lag Effect Artifact Correction in a Cone-Beam Flat Panel micro-CT System for Small Animal Imaging." Thesis, KTH, Skolan för teknik och hälsa (STH), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-179873.
Full textAbstract:
The cone-beam flat panel micro-CT is a high definition imaging system. It acquires projections of an object or animal to reconstruct a 3D image of its internal structure. The device is basically composed by a radiation tube and a detector panel, which are fixed to a gantry that rotates all around the test subject. The micro-CT system is affected by several imperfections and problems, that might lead to serious artifacts that deteriorate the quality of the reconstructed image. In particular, two issues have been discussed in the present work: the source-panel geometric misalignment and the detector lag effect. The first problem concerns the consequences of systems where the different elements are not perfectly aligned to each other. The second issue regards the residual signal, left in the detector's sensor after a projection acquisition, which affects the following frames with ghost images. Both these arguments have been investigated to describe their characteristics and behaviour in a typical acquisition protocol. Then two correction methods have been presented and tested on a real micro-CT device to verify their effectiveness in the artifacts compensation. In the end, a comparison between images before and after the corrections is provided and future prospects are discussed.
31
Lefrançois, William. "Développements méthodologiques en imagerie cardiovasculaire par résonance magnétique chez le petit animal." Thesis, Bordeaux 2, 2011. http://www.theses.fr/2011BOR21833/document.
Full textAbstract:
L’imagerie cardiovasculaire du rongeur par RMN est un véritable défi en ce qui concerne la résolution spatiale et temporelle, le contraste et le temps d’expérience. S’il est aujourd’hui admis que l’acquisition 3D doit être privilégiée chez le petit animal, les temps d’acquisition en 3D sont parfois très longs. Ils doivent pourtant rester compatibles avec les temps d’expérience in vivo. L’objectif de cette thèse était donc de développer de nouvelles méthodes d’imagerie cardiovasculaire 3D rapides pour le petit animal à 4.7 et 9.4 T. Tout d’abord, nous avons développé deux méthodes d’IRM cardiaque 4D (3D résolue dans le temps) à contraste «sang noir». La première méthode est basée sur une séquence TrueFISP (Fast Imaging with Steady-state Precession). Elle a permis d’obtenir le contraste sang noir en une heure d’acquisition. La deuxième méthode est basée sur une séquence FLASH (Fast Low Angle Shot). Elle utilise un gradient bipolaire pour supprimer le signal sanguin et le contraste a été rehaussé en Manganèse. Trente minutes d’acquisition ont alors été suffisantes. Ensuite, une méthode d’angiographie temps-de-vol 3D du corps entier de la souris a été développée. Le contraste vasculaire a été amélioré grâce à l’adjonction de motifs de suppression du signal tissulaire. L’imagerie de l’arbre vasculaire entier a pu être réalisé en moins de 10 minutes. Enfin, une nouvelle méthode d’angiographie fonctionnelle ciné temps-de-vol 4D utilisant une acquisition écho-planar a été développée. Les résultats préliminaires montrent qu’il est possible de diviser par quatre les temps d’acquisition de l’angiographie fonctionnelle classique. Tous ces résultats montrent que l’imagerie cardiovasculaire 3D haute résolution est possible dans des temps d’acquisition raisonnables voire rapidesCardiovascular MRI in rodents is a real challenge in terms of spatial and temporal resolution, contrast and experiment times. Though it is accepted that 3D acquisition should be preferred in small animals, 3D acquisition times can be very long. However, they must remain compatible with in vivo experiment times. The aim of this thesis was therefore to develop new fast 3D methods of cardiovascular imaging in small animals at 4.7 and 9.4 T. First, two 4D cardiac MRI methods (3D time resolved) were developed in «black-blood» contrast. The first method is based on a TrueFISP sequence (Fast Imaging with Steady-state Precession). It allowed to make black blood contrast in one hour acquisition time. The second method is based on a FLASH sequence (Fast Low Angle Shot). It uses a bipolar gradient to suppress the blood signal and the contrast was enhanced by using Manganese. Thirty minutes were then enough. Next, a time-of-flight angiography method for the whole body of mice was developed. The vascular contrast was improved by adding preparation modules to suppress the signal from tissues. The imaging of the whole arterial tree was realized within less than ten minutes. Finally, a new 4D time-of-flight method of functional cine angiography with echo-planar acquisition was developed. Preliminary results showed that acquisition times could be divided by four compared with those in classical functional angiography. All these results show that high resolution 3D cardiovascular imaging is possible in reasonable or even fast acquisition times
32
Cosette, Jérémie. "Design and optimization of small animal non-invasive imaging approaches for evaluating the effects of innovative treatments of Primary Central Nervous System Lymphomas." Thesis, Paris 5, 2014. http://www.theses.fr/2014PA05T069/document.
Full textAbstract:
Pas de résumé en françaisPrimary central nervous system lymphomas (PCNSL) are very aggressive malignancies with poor survival rate even with treatments (survival median is 44 months). This disease affects immune cells (lymphocytes) and forms diffuse and non-surgically removable tumor in the central nervous system. High-dose chemotherapy and radiotherapy are the common treatments with severe side effects. New therapeutic approaches are required for increasing treatment efficiency. We focused on primary intraocular lymphomas (PIOL) and primary cerebral lymphomas (PCL), which are subtypes of PCNSL. PIOL and PCL cells have a high propensity to migrate and form metastases in the brain and in the controlateral eye in the case of PIOL, and in the eye in the PCL case. However, metastatic dissemation mechanisms remain unclear. The objective of the present work was to study the effects of innovative treatments of B-cell lymphoma on primary tumor, on metastases, and on circulating tumor cells in PIOL and PCL immunocompetent syngeneic murine models of lymphomas using non-invasive in vivo imaging methods. We studied the effects of Ublituximab, a glycoengineered anti-CD20 monoclonal antibody (mAb), and CpG-ODN, a TLR-9 agonist, in mouse models. We showed that Ublituximab exhibits significant anti-tumor effect in PIOL and PCL, while CpG showed significant anti-tumor effect in PCL. We monitored the tumor burden and metastases using innovating non-invasive optical imaging or cell detection methods: bioluminescence imaging (BLI) and in vivo flow cytometer (IVFC). BLI was used to locate metastasis and to quantify tumor burden. We indeed developed a bioluminescence-based tumor burden quantification method that reduces user-dependence, allows comparisons between experiments, reveals statistical relevance, and which is easy to use. An IVFC device was set up to investigate the role of circulating tumor cells (CTCs) in PIOL and PCL. This fluorescence-based technique allows detection of CTCs by analyzing the cells flowing in blood vessels. However we had to overcome the problem of autofluorescence and tissue absorption. Two approaches were studied in parallel: a elaborating new cell line expressing far red fluorescent proteins, modulating the excitation light of an IVFC device to give the cell a unique signature therefore enhancing sensitivity, increasing signal to noise ratio. The modulated excitation IVFC allowed us to calculate the velocity of cells, and infer their position in blood vessel phantoms. The analysis of treatment effects on tumor burden, metastases and CTCs in PIOL and PCL could help understanding lymphoma metastatic dissemination and contribute to treatment follow-up, thus allowing design of new therapeutic approaches with increased efficacy
33
Namati, Jacqueline Thiesse. "Phenotype characterization of lung structure in inbred mouse strains using multi modal imaging techniques." Diss., University of Iowa, 2009. https://ir.uiowa.edu/etd/256.
Full textAbstract:
Research involved in modeling human lung disease conditions has provided insight into disease development, progression, and treatment. In particular, mouse models of human pulmonary disease are increasingly utilized to characterize lung disease conditions. With advancements in small animal imaging it is now possible to investigate the phenotypic differences expressed in inbred mouse strains in vivo to investigate specific disease conditions that affect the lung.
In this thesis our aim was to generate a comprehensive characterization of the normative mouse lung phenotypes in three of the most utilized strains of mice, C57BL/6, A/J, and BALB/c, through imaging techniques. The imaging techniques that we utilized in this research included micro-CT, a custom Large Image Microscope Array (LIMA) system for 3D microscopy, and classical histology. Micro-CT provided a non-destructive technique for acquiring in vivo and fixed lung images. The LIMA 3D microscopy system was utilized for direct correspondence of the gold standard histology images as well as to validate the anatomical structures and measurements that were extracted from the micro-CT images. Finally, complete lung histology slices were utilized for assessment of the peripheral airspace structures that were not resolvable using the micro-CT imaging system.
Through our developed imaging acquisition and processing strategies we have been able to successful characterize important phenotypes in the mouse lung that have not previously been known as well as identify strain variations. These findings will provide the scientific community with valuable information to be better equipped and capable of pursuing new avenues of research in investigating pulmonary disease conditions that can be modeled in the mouse.
34
Rabell, Montiel Adela. "Development of acoustic tissue mimicking materials for preclinical ultrasound imaging applications." Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/31342.
Full textAbstract:
Many applications of ultrasound test phantoms require that the acoustical properties of the phantom should closely match those of soft tissue. Numerous commercial test phantoms of this type are available for use with clinical ultrasound scanners, which use frequencies up to 20 MHz. However, scanners designed for imaging small animals in preclinical studies, typically operate at much higher frequencies. No commercially available test phantoms exist for use at frequencies above 20 MHz. The aim of this work was to develop a tissue-mimicking-material (TMM) that closely matches the acoustic properties of small animal tissues at high frequencies (HF). Such a material would, therefore, be suitable for ultrasound test phantoms for application with HF ultrasound scanners (20 MHz to 50 MHz). A three-step approach was adopted to address this lack of a suitable HF-TMM. Firstly, verify the acoustic characteristics of the existing IEC agar-based TMM. Secondly, establish the acoustic properties (speed of sound and attenuation coefficient) of small animal tissue at high frequencies. Thirdly, develop a TMM which exhibits, as closely as possible, these small animal tissue acoustic characteristics. A pulse-echo substitution method was used throughout to characterise the materials and the tissue samples. The speed of sound and attenuation coefficient of an IEC agar-based TMM were measured using two different techniques. Initially, a widely used method was tried, where samples are wrapped in film and placed in degassed, deionised water for assessment. The second technique was developed and validated for use in this work. In this method, TMM samples were uncovered (without film) and were both stored and assessed in a TMM preserving fluid. The second method provided up to four times more consistent results. The acoustical properties of the individual components of the IEC agar-based TMM were then measured in order to determine whether the overall attenuation coefficient of the agar TMM was a linear sum of the attenuation coefficients of its component parts. Within experimental uncertainties, this was found to be the case. This is a key observation from which the formulation of an agar TMM, matching the acoustic properties of small animal tissue, can be facilitated. The acoustical properties (speed of sound and attenuation coefficient) of mouse brain, liver, and kidney were measured using a preclinical ultrasound scanner.
35
Dillenseger, Jean-Philippe. "Imagerie préclinique multimodale chez le petit animal : qualification des instruments et des méthodes (IRM, µTDM et µTEMP)." Thesis, Strasbourg, 2017. http://www.theses.fr/2017STRAD026/document.
Full textAbstract:
L’imagerie préclinique se pratique majoritairement sur des modèles animaux murins principalement des souris (61%), elle représente une étape indispensable en recherche préclinique car elle suit les deux premières recommandations de la règle des 3R (réduction, raffinement et remplacement). Pour donner une signification biologique aux mesures extraites des images acquises in vivo chez la souris, il est nécessaire d’évaluer les performances des instruments utilisés mais également des procédures expérimentales en jeu. La qualification des appareils nécessite l’usage de fantômes spécifiques, et l’évaluation des méthodes impose de tester les procédures sur des individus non pathologiques, avant le passage aux expérimentations proprement dites. L’objectif de ce travail a été de développer des outils et des méthodes permettant de qualifier les instruments d’imagerie et certaines procédures in vivo. La nécessité de quantification, à partir d’images réalisées chez le petit animal, nous amène à considérer les instruments d’imagerie préclinique comme des outils métrologiques ; ce qui amène à intégrer le principe d’incertitude de mesure dans l’expression des résultatsPreclinical imaging is mostly performed on mouse animal models (61%). It is a necessary step in preclinical research, in compliance the first two recommendations of the 3Rs rules (reduction, refinement and replacement). In order to give a biological significance to measurements extracted from in vivo-acquired mouse images, it is necessary to evaluate instruments performances but also experimental procedures involved. The qualification of apparatuses requires the use of specific phantoms while the evaluation of methods requires procedures tests on non-pathological animals before experimentations. The scope of this work was to develop tools and methods to qualify imaging instruments and in vivo procedures. The need for quantification in small animal imaging, leads us to consider preclinical imaging instruments as metrological tools; which means integrating measurement uncertainty into
36
Bergeron, Mélanie. "Construction et expérimentation d'un scanner bimodal TEP/TDM combiné de résolution spatiale submillimétrique pour petits animaux." Thèse, Université de Sherbrooke, 2015. http://hdl.handle.net/11143/6755.
Full textAbstract:
Résumé : La tomographie d’émission par positrons (TEP) permet une imagerie fonctionnelle et moléculaire qui peut bénéficier de l’utilisation conjointe de la tomodensitométrie (TDM), d’abord pour fournir un support anatomique aux images TEP, mais aussi pour permettre une correction plus précise des images TEP. Les appareils existants sont composés de deux scanners juxtaposés nécessitant un déplacement du sujet entre les deux acquisitions, ce qui peut causer des artéfacts de mouvement dans l’image fusionnée TEP/TDM. De plus, le mode de fonctionnement des scanners TDM, basé sur l’intégration du flux de rayons X, délivre une dose de radiations relativement élevée qui peut interférer avec la réalisation d’études/protocoles d’imagerie longitudinales. La réalisation d’un appareil TEP/TDM partageant le même système de détection basé sur le détecteur LabPET II pourrait remédier à ces problèmes. Dans un premier temps, le module de détection LabPET II a été caractérisé pour la TEP et la TDM. Les premières études d’imagerie TDM avec ce détecteur ont aussi été conduites avec un simulateur. Ce travail a permis de déceler un phénomène de diaphonie optique au sein du module de détection. La recherche d’une solution à ce problème a motivé l’évaluation de nouveaux types de réflecteurs métallisés, donc plus opaques, pour en limiter les effets. Le signal relativement faible détecté en TDM a par la suite mené à explorer des scintillateurs alternatifs présentant un rendement lumineux supérieur. L’un de ces scintillateurs permettra d’améliorer sensiblement les performances du scanner LabPET I et pourrait être retenu pour la génération future de scanners LabPET II. || Abstract : Positron emission tomography (PET) provides functional and molecular imaging capabilities that can benefit from joint use with computed tomography (CT), first to provide anatomical support to PET images, but also to allow a more precise correction of PET images. Existing devices are composed of two back-to-back scanners which require displacing the subject between the two acquisitions, possibly causing motion artifacts in the fused PET/CT images. Moreover, the operation mode of CT scanners based on the X-ray signal integration delivers a relatively high radiation dose that can interfere with longitudinal imaging studies/protocols. The realization of a PET/CT scanner sharing the same detection system for both 511 keV and X-ray photons and based on the LabPET II could remedy these problems. As a first step, a characterization of the detection module LabPET II was performed in PET and CT mode. The first CT imaging studies with this detector were also conducted with a simulator. This work allowed identifying an optical crosstalk phenomenon in the detection module. The search for a solution to this problem has motivated the evaluation of new types of metallized, more opaque, reflectors to limit crosstalk effects. The relatively low signal detected in CT led us to explore alternative scintillators having a higher light output. One of these scintillators will significantly improve the performance of the LabPET I scanner and could be used for the next generation of LabPET II scanners.
37
Brard, Emmanuel. "La tomographie à émission de positrons à géométrie axiale : de l’imagerie de la souris au cerveau humain." Thesis, Strasbourg, 2013. http://www.theses.fr/2013STRAE003/document.
Full textAbstract:
La tomographie par émission de positrons est une technique d’imagerie nucléaire utilisant des noyaux radioactifs. Elle est utilisée dans le domaine clinique et préclinique. Cette dernière nécessite l’utilisation de petits animaux, comme la souris. Comme en imagerie clinique, l’objectif est d’obtenir le meilleur signal avec la meilleure précision spatiale possible. Cependant, un rapport d’échelle homme-souris suggère une résolution inférieure à 1 mm3. Un imageur conventionnel est constitué de modules de détection entourant le patient, orientés radialement. Cette approche lie efficacité et résolution spatiale. Ce travail concerne l’étude de la géométrie axiale. Les éléments de détection sont ici orientés parallèlement à l’objet. Ceci limite la corrélation entre efficacité de détection et résolution spatiale, et ainsi permet d’obtenir une haute résolution et haute sensibilité. La simulation de prototypes a permis d’envisager une résolution spatiale moyenne inférieure au millimètre et une efficacité de 15 ou 40% selon l’extension axiale. Ces résultats permettent de présager de bonnes perspectives en imageries préclinique et cliniquePositrons emission tomography is a nuclear imaging technics using nuclear decays. It is used both in clinical and preclinical studies. The later requires the use of small animals such as the mouse. The objective is to obtain the best signal with the best spatial resolution. Yet, a weight ratio between humans and mice indicates the need of a sub-millimeter resolution. A conventional scanner is based on detection modules surrounding the object to image and arranged perpendicularly. This implies a strong relationship between efficiency and spatial resolution. This work focuses on the axial geometry in which detection modules are arranged parallel to the object. This limits the relationship between the figures of merit, leading to both high spatial resolution and efficiency. The simulations of prototypes showed great perspectives in term of sub-millimeter resolution with efficiencies of 15 or 40% according to the scanner’s axial extension. These results indicate great perspectives for both clinical and preclinical imaging
38
Ma, Xiaopeng [Verfasser], Vasilis [Akademischer Betreuer] [Gutachter] Ntziachristos, Moritz G. F. [Gutachter] Wildgruber, and Bernhard [Gutachter] Wolfrum. "Assessment of hybrid FMT-XCT for respiratory and cardiovascular small animal imaging applications / Xiaopeng Ma ; Gutachter: Moritz G. F. Wildgruber, Bernhard Wolfrum, Vasilis Ntziachristos ; Betreuer: Vasilis Ntziachristos." München : Universitätsbibliothek der TU München, 2017. http://d-nb.info/1126644110/34.
Full text
39
Bled, Emilie. "Développements méthodologiques de l’IRM en 3D chez la souris : résolution temporelle et sensibilité du contraste." Thesis, Bordeaux 2, 2012. http://www.theses.fr/2012BOR21934.
Full textAbstract:
Pour répondre à des questions biologiques émergentes, l’IRM 3D in vivo est une approche de choix, mais elle souffre principalement d’une faible résolution temporelle en raison d’une faible sensibilité. Par ailleurs, l’IRM gagnerait à une meilleure sensibilité aux agents de contrastes exogènes. Il est proposé ici des développements en IRM du petit animal permettant de réduire considérablement la durée d’acquisition des images à trois dimensions chez la souris, ou la détection de très faibles quantités d’agents de contraste. Ces développements reposent sur la manipulation de l’espace-k (espace des données acquises). La première partie de ce travail a reposé sur la mise en place d’une méthode d’acquisition rapide de l’imagerie 3D permettant de conserver la qualité de l’image. Le «keyhole» 3D a été la technique choisie pour accéder à une résolution temporelle très élevée. Ainsi, le temps d’acquisition en imagerie ciné 3D cardiaque, chez la souris, a été réduit par un facteur 4 tout en conservant la qualité de l’image (SSB) et les informations extraites. Le «keyhole» 3D est aussi une méthode favorable à la mesure de prise de contraste. La biodistribution d’agent de contraste, peut être suivie en imagerie 3D à contrastes T1 et T2* dans le corps entier de la souris en quasi temps réel. La manipulation de l’espace-k permet aussi d’améliorer la qualité de l’image en réalisant une imagerie très sensible au contraste T2*. Pour cela, la correction de mouvements intrinsèques, comme ceux issus de la respiration au niveau de l’abdomen, générant un effet de perte de résolution spatiale, est indispensable. L’utilisation d’un écho navigateur permettant de détecter et de supprimer tous les signaux indésirables apporte une amélioration nette de la qualité d’image. Le seuil de détection de l’agent de contraste testé est d’ailleurs inférieur à 100 picomole de fer par kilogramme dans l’abdomen de souris. L’utilisation des propriétés de l’espace-k montre à quel point la qualité de l’image peut être améliorée et adaptée à l’information souhaitée. C’est un moyen peu couteux et efficace pour rendre l’imagerie par résonance magnétique encore plus performante en terme de résolution spatiale et de résolution temporelleIn vivo 3D MRI is a powerful method which can be used to answer emerging biological issues. However, low temporal resolution due to intrinsic low sensitivity is one of its main drawbacks. Similarly, breakthroughs are needed to detect by MRI low-concentrated contrast agents used for molecular imaging. In this work, several methodology developments in small animals are proposed to greatly reduce acquisition times of 3D MRI and to increase contrast sensitivity to T2* agents. Both achievements were performed through the manipulation of the k-space, i.e the acquired data space in a retrospective approach. To achieve very high temporal resolution a 3D keyhole technique was chosen. This allowed the acquisition time in cardiac 3D-cine imaging in mice to be reduced by a factor 4. Image quality (signal-to-noise ratio) and the extracted functional data were preserved. Interestingly, 3D keyhole imaging also allowed the evaluation of T1 and T2* contrast enhancement and biodistribution in real time in the whole mouse body. In the last part of the work, the goal was to generate highly T2*-sensitive 3D images in mouse abdomen to detect diluted iron-oxide-based contrast agents. The use of a navigator echo enabled efficient motion correction and detection threshold of less than 100 picomol iron per kilogram. The results are discussed in a general frame of future applications and development of fast and highly-resolved 3D imaging
40
Namati, Eman, and eman@namati com. "Pre-Clinical Multi-Modal Imaging for Assessment of Pulmonary Structure, Function and Pathology." Flinders University. Computer Science, Engineering and Mathematics, 2008. http://catalogue.flinders.edu.au./local/adt/public/adt-SFU20081013.044657.
Full textAbstract:
In this thesis, we describe several imaging techniques specifically designed and developed for the assessment of pulmonary structure, function and pathology. We then describe the application of this technology within appropriate biological systems, including the identification, tracking and assessment of lung tumors in a mouse model of lung cancer.
The design and development of a Large Image Microscope Array (LIMA), an integrated whole organ serial sectioning and imaging system, is described with emphasis on whole lung tissue. This system provides a means for acquiring 3D pathology of fixed whole lung specimens with no infiltrative embedment medium using a purpose-built vibratome and imaging system. This system enables spatial correspondence between histology and non-invasive imaging modalities such as Computed Tomography (CT), Magnetic Resonance Imaging (MRI) and Positron Emission Tomography (PET), providing precise correlation of the underlying 'ground truth' pathology back to the in vivo imaging data. The LIMA system is evaluated using fixed lung specimens from sheep and mice, resulting in large, high-quality pathology datasets that are accurately registered to their respective CT and H&E histology.
The implementation of an in vivo micro-CT imaging system in the context of pulmonary imaging is described. Several techniques are initially developed to reduce artifacts commonly associated with commercial micro-CT systems, including geometric gantry calibration, ring artifact reduction and beam hardening correction. A computer controlled Intermittent Iso-pressure Breath Hold (IIBH) ventilation system is then developed for reduction of respiratory motion artifacts in live, breathing mice. A study validating the repeatability of extracting valuable pulmonary metrics using this technique against standard respiratory gating techniques is then presented.
The development of an ex vivo laser scanning confocal microscopy (LSCM) and an in vivo catheter based confocal microscopy (CBCM) pulmonary imaging technique is described. Direct high-resolution imaging of sub-pleural alveoli is presented and an alveolar mechanic study is undertaken. Through direct quantitative assessment of alveoli during inflation and deflation, recruitment and de-recruitment of alveoli is quantitatively measured. Based on the empirical data obtained in this study, a new theory on alveolar mechanics is proposed.
Finally, a longitudinal mouse lung cancer study utilizing the imaging techniques described and developed throughout this thesis is presented. Lung tumors are identified, tracked and analyzed over a 6-month period using a combination of micro-CT, micro-PET, micro-MRI, LSCM, CBCM, LIMA and H&E histology imaging. The growth rate of individual tumors is measured using the micro-CT data and traced back to the histology using the LIMA system. A significant difference in tumor growth rates within mice is observed, including slow growing, regressive, disappearing and aggressive tumors, while no difference between the phenotype of tumors was found from the H&E histology. Micro-PET and micro-MRI imaging was conducted at the 6-month time point and revealed the limitation of these systems for detection of small lesions ( < 2mm) in this mouse model of lung cancer. The CBCM imaging provided the first high-resolution live pathology of this mouse model of lung cancer and revealed distinct differences between normal, suspicious and tumor regions. In addition, a difference was found between control A/J mice parenchyma and Urethane A/J mice normal parenchyma, suggesting a 'field effect' as a result of the Urethane administration and/or tumor burden. In conclusion, a comprehensive murine lung cancer imaging study was undertaken, and new information regarding the progression of tumors over time has been revealed.
41
Omidvari, Negar [Verfasser], Stephan [Akademischer Betreuer] Paul, Stephan [Gutachter] Paul, and Sibylle [Gutachter] Ziegler. "Development and Characterization of MADPET4: A High Resolution Small Animal Positron Emission Tomography Insert for a 7 T Magnetic Resonance Imaging Scanner / Negar Omidvari ; Gutachter: Stephan Paul, Sibylle Ziegler ; Betreuer: Stephan Paul." München : Universitätsbibliothek der TU München, 2018. http://d-nb.info/1170872611/34.
Full text
42
Manook, André [Verfasser], Markus [Akademischer Betreuer] Schwaiger, and Johann [Akademischer Betreuer] Förstl. "Preclinical PET as Translational Tool for Imaging Alzheimer's Disease : Small-Animal PET Imaging of Beta-Amyloid Plaques with [11C]PiB, its Multi-Modal Validation and Application to the Evaluation and Ranking of New AD Tracers / André Manook. Gutachter: Markus Schwaiger ; Johann Förstl. Betreuer: Markus Schwaiger." München : Universitätsbibliothek der TU München, 2012. http://d-nb.info/1047883465/34.
Full text
43
Kastis, Georgios. "Multi-modality imaging of small animals." Diss., The University of Arizona, 2002. http://hdl.handle.net/10150/289830.
Full textAbstract:
Over the last few years there has been a great demand for noninvasive, dedicated, small-animal imaging systems for biomedical research applications. In this dissertation we will discuss the development and performance of two gamma-ray systems and a dual modality CT/SPECT system. Initially we introduce FASTSPECT, a stationary, scintillator-based, single-photon emission computed tomography (SPECT) system that was originally built as a brain imager. We discuss its transformation into a small-animal imaging system and validate its performance by presenting high-resolution images of phantoms and animals. Furthermore, we discuss the development of an in vivo imaging protocol for rat myocardial models using FASTSPECT. The infarct size obtained from the images is quantified and compared with the myocardial infarct size measured from histology. Semiconductor detectors can exhibit good spatial and energy resolution, and therefore offer a promising alternative to scintillation technology. We discuss the performance of a semiconductor detector system, previously developed in our group, for planar and tomographic imaging of small animals. The same gamma-ray detector is used in a dual modality system for imaging mice. The system combines an anatomical imaging modality, x-ray CT, with a functional modality, SPECT. We present the development of the CT/SPECT system and illustrate its performance by presenting high-resolution images of phantoms and mice. Finally, we introduce a procedure for evaluating estimation methods without the use of a gold standard.
44
Jiménez, González Xavier. "Improvements in the registration of multimodal medical imaging : application to intensity inhomogeneity and partial volume corrections." Doctoral thesis, Universitat Politècnica de Catalunya, 2016. http://hdl.handle.net/10803/458881.
Full textAbstract:
Alignment or registration of medical images has a relevant role on clinical diagnostic and treatment decisions as well as in research settings. With the advent of new technologies for multimodal imaging, robust registration of functional and anatomical information is still a challenge, particular in small-animal imaging given the lesser structural content of certain anatomical parts, such as the brain, than in humans. Besides, patient-dependent and acquisition artefacts affecting the images information content further complicate registration, as is the case of intensity inhomogeneities (IIH) showing in MRI and the partial volume effect (PVE) attached to PET imaging. Reference methods exist for accurate image registration but their performance is severely deteriorated in situations involving little images Overlap. While several approaches to IIH and PVE correction exist these methods still do not guarantee or rely on robust registration. This Thesis focuses on overcoming current limitations af registration to enable novel IIH and PVE correction methods.El registre d'imatges mèdiques té un paper rellevant en les decisions de diagnòstic i tractament clíniques així com en la recerca. Amb el desenvolupament de noves tecnologies d'imatge multimodal, el registre robust d'informació funcional i anatòmica és encara avui un repte, en particular, en imatge de petit animal amb un menor contingut estructural que en humans de certes parts anatòmiques com el cervell. A més, els artefactes induïts pel propi pacient i per la tècnica d'adquisició que afecten el contingut d'informació de les imatges complica encara més el procés de registre. És el cas de les inhomogeneïtats d'intensitat (IIH) que apareixen a les RM i de l'efecte de volum parcial (PVE) característic en PET. Tot i que existeixen mètodes de referència pel registre acurat d'imatges la seva eficàcia es veu greument minvada en casos de poc solapament entre les imatges. De la mateixa manera, també existeixen mètodes per la correcció d'IIH i de PVE però que no garanteixen o que requereixen un registre robust. Aquesta tesi es centra en superar aquestes limitacions sobre el registre per habilitar nous mètodes per la correcció d'IIH i de PVE.
45
Portal, Loriane. "Etude de la tomographie à comptage de rayons X avec des pixels hybrides en Si et en CdTe et application au suivi longitudinal du carcinome hépatocellulaire chez la souris." Thesis, Aix-Marseille, 2018. http://www.theses.fr/2018AIXM0351/document.
Full textAbstract:
Ma thèse de doctorat s’inscrit à l’interface entre la physique expérimentale et la biologie. Ce travail a été développé au sein de l’équipe imXgam du CPPM, qui a construit un prototype de micro-tomographie pour le suivi non-invasif du petit animal, équipé d’une caméra à pixels hybrides XPAD3 fonctionnant en mode comptage de rayons X. Le comptage de rayons X rendu possible par la technologie des pixels hybrides, permet de s’affranchir du bruit électronique et d’augmenter ainsi la détectabilité des tissus faiblement contrastés. Elle présente de plus la capacité d'appliquer à chaque pixel un seuil de détection en énergie permettant d’accéder à l’information spectrale des rayons X détectés et ouvre la voie au développement d’une méthode d’imagerie spectrale dite au K-edge, qui permet de différencier des agents de contraste particuliers. La caméra XPAD3 développée avec un capteur en Si présente une efficacité de détection qui limite son utilisation pour l’imagerie du vivant. Une caméra XPAD3 avec une meilleure efficacité au delà de 25 keV a été assemblée avec des capteurs en CdTe. Dans un premier temps, nous avons effectué une comparaison des caméras XPAD3/Si et XPAD3/CdTe en imagerie d’absorption standard et en imagerie au K-edge. Nous avons ensuite, en collaboration avec des biologistes de l’IBDM, assuré le suivi quantitatif et in vivo sur plusieurs mois, du développement de tumeurs hépatiques chez un modèle spécifique de souris et de l’efficacité d’un traitement ciblant les cellules tumorales. Enfin, nous avons développé un protocole d’acquisition spectrale à faible dose pour réaliser une tomographie spectrale in vivo d’un foie de souris en exploitant le K-edge du baryumMy PhD thesis is at the interface between experimental physics and biology. This work has been developed within the imXgam team at CPPM, which has built a micro-computed tomography prototype for the non-invasive longitudinal monitoring of small animal, equipped with the XPAD3 hybrid pixel camera that operates in X-ray photon counting mode. X-ray photon counting that has been made possible by hybrid pixels, allows to free images from the electronic noise and thus to increase detectability of weakly contrasted tissues. Moreover, it provides the possibility to set an energy threshold for each pixel that allows to accessing spectral information on the detected X-rays and paving the way to the development of a spectral imaging modality also named K-edge imaging, which allows to differentiate selected contrast agents. Actually, the XPAD3 camera developed with a Si sensor presents a low detective efficiency that limits its use for biomedical imaging. A XPAD3 camera with a better efficiency above 25 keV has been assembled with high-Z CdTe sensors. Firstly, we have performed a comparison of XPAD3/Si and XPAD3/CdTe cameras for standard absorption CT and K-edge imaging. Then, in collaboration with a team of biologists from IBDM, we have carried out the quantitative and in vivo follow-up of hepatic tumour development in a specific mouse model over several months, and of the effectiveness of a treatment targeting these tumour cells. Finally, we have developed a protocol for low dose acquisition of spectral data to realize an in vivo spectral tomography of a mouse liver using the barium spectral signature
46
Marchadier, Arnaud. "Analyses d'images de tomographie X chez le petit animal : applications aux études de phénotypage ex vivo et in vivo." Phd thesis, Université d'Orléans, 2011. http://tel.archives-ouvertes.fr/tel-00779806.
Full textAbstract:
L'imagerie du petit animal est incontournable pour le développement des recherches dans les secteurs de labiologie, de la médecine et de l'industrie pharmaceutique. Parmi les différentes modalités d'imagerie développéeschez l'humain et adaptées à l'animal, l'imagerie tomographique à rayons X est devenue une référencepour l'analyse des caractères anatomiques et phénotypiques chez la souris. Elle permet de réaliser des étudeslongitudinales in vivo et des analyses haute résolution ex vivo de façon non invasives et en 3D. L'analyse deces images 3D nécessite des outils spécifiques à chaque problématique.Dans ce contexte, notre travail de thèse a permis d'apporter des contributions sur les thématiques suivantes :1. le développement d'outils d'analyse, à la fois quantitatifs et qualitatifs, pour l'imagerie des tissusminéralisés et adipeux2. l'application des méthodologies développées à des problématiques de recherche biomédicale3. l'étude comparative et "multi-échelle" de différentes technologies de tomographie X pour l'imagerie dupetit animal4. la mise au point d'une méthode originale par résonnance paramagnétique électronique pour la dosimétried'un acte d'imagerie X chez le petit animalEn conclusion, les outils d'imagerie 3D que nous avons développés représentent un nouvel apport pour la dissectionvirtuelle de l'animal de laboratoire, permettant l'exploration de nombreux tissus et organes et rivalisantavec les méthodes d'histologie et de microscopie électronique.L'application de ces méthodes d'imagerie pour la recherche fondamentale et pré-clinique ouvre la perspectived'une alternative nouvelle dans l'expérimentation animale.
47
Brullé, Laura. "Développement de stratégies d'imagerie multimodalités pour la pharmacologie des agents anticancéreux." Phd thesis, Université d'Orléans, 2012. http://tel.archives-ouvertes.fr/tel-00747343.
Full textAbstract:
L'imagerie préclinique dans le domaine de la cancérologie est en plein essor. Elle permet grâce à des modèles animaux représentatifs de cancers humains de comprendre les mécanismes de développement des pathologies et d'évaluer l'efficacité thérapeutique d'un nouveau traitement. Le principal objectif de ce travail a été de développer deux modèles orthotopiques de cancer (pancréas et colon) et d'évaluer des traitements de références ainsi qu'une nouvelle stratégie thérapeutique par plasma froid fibré appelée Plasma Gun. Les 2 modèles de cancers développés ont montré une bonne représentativité vis-à-vis des cancers humains, avec l'apparition de métastases à distance et la présence de zones hypoxiques. Le 5-fluorouracile pour le modèle orthotopique de carcinome colorectal HCT116-luc et la gemcitabine pour le modèle d'adénocarcinome pancréatique MIA PaCa2-luc ont induit à faible dose des effets discrets pouvant être mis en évidence grâce aux modalités d'imageries mises en oeuvre. Après validation de nos démarches expérimentales une nouvelle stratégie thérapeutique, le Plasma Gun, a été évaluée et a montré des effets significatifs sur l'inhibition de la croissance tumorale. Le second objectif de ma thèse a été de mettre en oeuvre des outils pour l'induction et la caractérisation des métastases osseuses ainsi que pour l'imagerie haute résolution de la vascularisation. D'une part, les métastases osseuses obtenues par injection de cellules PC3M-luc en intracardiaque ont été évaluées et quantifiées grâce à différentes modalités d'imagerie (bioluminescence, scintigraphie et scanner X). D'autre part, la réalisation d'une imagerie haute résolution de la vascularisation a été possible grâce à la technique de casting qui permet de recréer la structure 3D de l'architecture vasculaire suite à l'injection d'une résine dans la circulation. Les développements réalisés lors de cette thèse ont ainsi permis d'apporter des outils pour l'évaluation préclinique de nouvelles thérapies anticancéreuses.
48
Ouamara, Hamid. "Comparaison de la micro-tomodensitométrie par comptage de photons et par intégration de charges avec le dispositif d'irradiation PIXSCAN." Thesis, Aix-Marseille, 2013. http://www.theses.fr/2013AIXM4004/document.
Full textAbstract:
L'approche développée par l'équipe imXgam du CPPM a consisté à adapter la technologie des pixels hybrides XPAD à l'imagerie biomédicale. C'est dans cette optique qu'un micro-tomodensitomètre PIXSCAN II basé sur la nouvelle génération de détecteurs à pixels hybrides appelés XPAD3 a été développé. Ce travail de thèse décrit la démarche engagée pour évaluer l'apport de la technologie à pixels hybrides en tomodensitométrie par rayons X en termes de contraste et de dose et pour explorer de nouvelles possibilités d'imagerie biomédicale à faible dose. L'évaluation des performances ainsi que la validation des résultats obtenus avec les données acquises avec le détecteur XPAD3 ont été comparées aux résultats obtenus avec la caméra CCD DALSA XR-4 similaire aux détecteurs utilisés dans la plupart des micro-TDM usuels. Le détecteur XPAD3 permet d'obtenir des images reconstruites d'une qualité satisfaisante et proche de celle des images de la caméra DALSA XR-4, mais avec une meilleure résolution spatiale. A faible dose, les images du détecteur XPAD3 sont de meilleure qualité que celles de la caméra CCD. Du point de vue de l'instrumentation, ce projet a prouvé le bon fonctionnement du dispositif PIXSCAN II pour la souris. Nous avons pu reproduire une qualité d'image semblable à celle obtenue avec un détecteur à intégration de charges de type caméra CCD. Pour améliorer les performances du détecteur XPAD3, il va falloir optimiser la stabilité des seuils et avoir des courbes de réponses des pixels en fonction de l'énergie assez homogènes en utilisant un capteur plus dense comme le CdTe par exempleThe pathway that has been followed by the imXgam team at CPPM was to adapt the hybrid pixel technology XPAD to biomedical imaging. It is in this context that the micro-CT PIXSCAN II based on the new generation of hybrid pixel detectors called XPAD3 has been developed. This thesis describes the process undertaken to assess the contribution of the hybrid pixel technology in X-ray computed tomography in terms of contrast and dose and to explore new opportunities for biomedical imaging at low doses. Performance evaluation as well as the validation of the results obtained with data acquired with the detector XPAD3 were compared to results obtained with the CCD camera DALSA XR-4 similar to detectors used in most conventional micro-CT systems. The detector XPAD3 allows to obtain reconstruced images of satisfactory quality close to that of images from the DALSA XR-4 camera, but with a better spatial resolution. At low doses, the images from the detector XPAD3 have a better quality that is those from CCD camera. From an instrumentation point of view, this project demonstrated the proper erations of the device PIXSCAN II for mouse imaging. We were able to reproduce an image quality similar to that obtained with a charge integration detector such as a CCD camera. To improve the performance of the detector XPAD3, we will have to optimize the stability of the thresholds and in order to obtain more homogeneous response curves of the pixels as a function as energy by using a denser sensor such as CdTe
49
Song, Yang. "Semi-Automatic Registration Utility for MR Brain Imaging of Small Animals." Digital WPI, 2014. https://digitalcommons.wpi.edu/etd-theses/148.
Full textAbstract:
The advancements in medical technologies have allowed more accurate diagnosis and quantitative assessments. Magnetic Resonance Imaging is one of the most effective and critical technologies in modern diagnosis. However, preprocessing tasks are required to perform various research topics basing on MR image. Registration is one of the those preprocessing tasks. In this research, a semi-automatic utility was developed for doing MRI registration of small animals. It focuses on 2D rigid body registration. The test results show that this developed utility can perform registration well for MRI of small animals in both intra-subject and inter-subjects.
50
Fang, Yu-Hua. "Quantification of Pharmacokinetics in Small Animals with Molecular Imaging and Compartment Modeling Analysis." Cleveland, Ohio : Case Western Reserve University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=case1238635584.
Full textAbstract:
Thesis (Ph.D.)--Case Western Reserve University, 2009Department of Biomedical Engineering Abstract Title from OhioLINK abstract screen (viewed on 10 April 2009) Available online via the OhioLINK ETD Center