Dissertations / Theses on the topic 'Spectroscoping imaging'
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1
Ross, Amy Psychiatry Faculty of Medicine UNSW. "Longitudinal study of cognitive and functional brain changes in ageing and cerebrovascular disease, using proton magnetic resonance spectroscopy." Awarded by:University of New South Wales. School of Psychiatry, 2005. http://handle.unsw.edu.au/1959.4/27329.
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The neurophysiological basis of cognition changes with age is relatively unexplained, with most studies reporting weak relationships between cognition and measures of brain function, such as event related potentials, brain size and cerebral blood flow. Proton magnetic resonance spectroscopy (1H-MRS) is an in vivo method used to detect metabolites within the brain that are relevant to certain brain processes. Recent studies have shown that these metabolites, in particular N-acetyl aspartate (NAA), which is associated with neuronal viability, correlate with performance on neuropsychological tests or other measures of cognitive function in patients with a variety of cognitive disorders associated with ageing and in normal ageing subjects. We have studied the relationship between metabolites and cognitive function in elderly patients 3 months and 3 years after a stroke or transient ischemic attack (TIA) and in an ageing comparison group. Metabolites were no different between stroke/TIA patients and elderly controls, however, there were significant metabolite differences between stroke/TIA patients with cognitive impairment (Vascular Cognitive Impairment and Vascular Dementia) and those without. Frontal measures of NAA and NAA/Cr predicted cognitive decline over 12 months and 3 years in stroke/TIA patients and elderly controls, and these measures were superior predictors than structural MRI measures. Longitudinal stability of metabolites in ageing over 3 years was associated with stability of cognitive function. The results indicate that 1H-MRS is a useful tool in differentiating stroke/TIA patients with and without cognitive impairment, with possibly superior predictive ability than structural MRI for assessing future cognitive decline. The changes in 1H-MRS that occur with ageing and cognitive decline have implications for the neurophysiological mechanisms and processes that are occurring in the brain, as well as application to clinical diagnosis, the early detection of pathology and the examination of longitudinal change.
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Davidson, David William. "Imaging and spectroscopic radiation detectors." Thesis, University of Glasgow, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.404443.
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Bao, Sumi. "Clinically relevant magnetic resonance imaging and spectroscopic imaging development." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/9133.
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Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1999.Includes bibliographical references (p. 129-137).
As one result of this thesis, a single slab 3D fast spin echo imaging (3DFSE) method has been implemented and optimized. This involved sequence design and implementation, SAR considerations, parameter adjustments and clinical testing. The method can deliver 3D Tl or T2 weighted brain image with isotropic Imm3 voxel resolution in approximately 10 minutes. The ability to obtain high spatial resolution in reasonable time periods has wide clinical applications such as improvement of treatment planning protocols for brain tumor patients, precise radiotherapy planning, and tissue segmentation for following the progression of diseases like multiple sclerosis. The other part of this thesis is devoted to developing and implementing spectroscopic imaging methods, which include 20 chemical shift imaging(2DCSI) methods, 20 line scan spectroscopic imaging(2D LSSI) methods, spin echo planar spectroscopic imaging(SEPSI) methods and ~ingle shot line scan spin echo planar spectroscopic imaging(SSLSEPSI) method. The former two methods are applied to oil phantoms and bone marrow studies. The SEPSI method can provide simultaneous spectroscopic measurements, R2 and R2' images and field distribution images. A time domain spectral analysis method, LP-HSVD was implemented and applied to spectroscopic imaging studies. The SEPSI method was applied to get lipid characterization of bone marrow as well as to get the R2 and R2' brain images. The SSLSEPSI method can provide instant line spectroscopic imaging which might be useful to image moving objects and can provide high temporal resolution for dynamic studies. With further development, both SEPSI and SSLSEPSI methods may prove useful for trabecular bone studies as well as functional magnetic resonance imaging( tMRI) studies.
by Sumi Bao.
Ph.D.
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Paul, Provakar. "Multipoint spectroscopic analyzing & imaging method." Thesis, Högskolan i Gävle, Avdelningen för elektronik, matematik och naturvetenskap, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-15274.
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Spectroscopy is a technique as the interaction of different radiation spectrum with matter to analysis of a sample. This thesis work proposed two methods are multiple pointes spectroscopies analyzing then imaging detection methods for solid samples. Developed method one is using Ultraviolet (UV), Visible (Vis) and Infrared (IR) detection. Where detection was assembled with deuterium as well tungsten-halogen lamp source (which were able to generate 175 nm to 3300 nm wavelength), a manual X-Y stepper for scan an inhomogeneous biological sample, optical design beside Indium gallium arsenide (InGaAs) detection unit was used of Lamda 950 by PerkingElmer. Second improved methodology is Vis detection imaging of samples. In Vis detection imaging was constructed with Helium-Neon (HeNe) red laser as a source (able to generate 632.8 nm wavelengths), a silicon pin photodiode detector, lens, multimeter, X-Y positioner stepper motors to scan samples. The work show successfully detected and imaged of water, fresh leaf, brain phantom in addition 3mm horizontal and 1.5 mm vertical cooper line. The thesis works proposed methods has obtained accurate results of all the samples detection specifically has devised imaging of samples. This spectroscopic process is suitable for any type of liquid, solid also gas detecting moreover imaging approach can be applicable in any type of inhomogeneous matter.
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Lau, Condon. "Detecting cervical dysplasia with quantitative spectroscopic imaging." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/106718.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2009.Includes bibliographical references.
This thesis extends quantitative spectroscopy, a form of model-based reflectance and fluorescence spectroscopy, from a small area, contact-probe implementation to wide-area quantitative spectroscopic imaging (QSI) for complete coverage of at-risk tissue. QSI uses the scanning virtual probe concept that is critical for model-based spectroscopy and offers spatial resolution advantages over conventional wide-field illumination. We develop a QSI system capable of imaging cervical dysplasia in vivo. Using the QSI system, we conduct a clinical study to train and prospectively evaluate QSI's ability to distinguish high-grade squamous intraepithelial lesions (HSIL) from non-HSILs (less severe conditions) in cervical transformation zone. This is a clinically important distinction because HSIL requires treatment. The results show measuring the per-patient normalized reduced scattering coefficient alone accurately performs the distinction. This is in good agreement with our previous contact-probe study of HSIL. Due to improved accuracy, QSI used as an adjunct to colposcopy can potentially reduce the number of unnecessary biopsies over colposcopy alone. The results also suggest a simplified optical instrument can be used to detect HSIL and this may advance cervical dysplasia detection in developing countries, where cervical cancer mortality is highest.
by Condon Lau.
Ph.D.
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Meng, Jiqun J. "Line scan proton magnetic resonance spectroscopic imaging." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/36963.
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Forsyth, Robert J. "Spectroscopic and imaging studies of nightglow variations." Thesis, University of Aberdeen, 1989. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU020230.
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A survey of the literature on the techniques used in and the results obtained from studies of nightglow variability is presented. Three microprocessor controlled instruments (an eight channel tilting filter spectrometer, an earlier six channel version and a CCD based low light level camera) have been constructed with the aim of studying variations in the nightglow, especially of the type associated with the passage of gravity waves through the emitting layers. The final stages of development of the eight channel spectrometer are described, including the design of automatic dark count and reference light systems, a temperature control system for the filters and an interface for transferring the spectrometer data into a computer. Calibration experiments to determine the wavelength, line shape and intensity response of this spectrometer are described. The development of suites of computer programmes for analysing the data from both spectrometers and the camera is then discussed. For the spectrometers, these perform the functions of subtraction of dark count, reduction of the calibration data to a form suitable for use in the analysis of data spectra in terms of a set of line shapes and continuum response functions, and execution of this analysis to produce plots of the emission intensities and OH rotational temperature versus time. For the camera, software was produced to allow separation of stellar images from the airglow emission; stellar image intensities were analysed in an attempt to characterise atmospheric absorption. Software was also written to correct airglow intensities for absorption and the van Rhijn effect and finally to reproject the images in the form of a map of the emitting layer. Observations made with the instruments working separately and in conjunction are described and the results are presented as an example of the performance of the instruments and the software.
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Fernandez, Daniel Celestino. "Fourier-transform infrared spectroscopic imaging of prostate histopathology." [Tampa, Fla.] : University of South Florida, 2003. http://purl.fcla.edu/fcla/etd/SFE0000617.
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Amrania, Hemmel. "Ultrafast Mid-Infrared Spectroscopic Imaging with Biomedical Applications." Thesis, Imperial College London, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.526408.
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Glassford, Stefanie Elizabeth. "Applications of ATR-FTIR spectroscopic imaging to proteins." Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/24835.
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Protein aggregation and crystallisation play an important role in the development of biopharmaceuticals and for structural proteomics but both processes are still poorly understood. There is a demand for new methods to screen the extensive range of conditions that promote crystallisation and aggregation as well as provide insight into the behaviour of the proteins. Attenuated Total Reflection (ATR)-Fourier Transform Infrared (FTIR) spectroscopic imaging is a powerful analytical tool which can be applied to study proteins. This technique combines ATR-FTIR spectroscopy with an infrared array detector allowing for both spatial and chemical information to be obtained from the sample. There are a range of imaging fields of view and spatial resolution possible with ATR-FTIR spectroscopic imaging and this presents multiple opportunities for the study of proteins. The purpose of this research was to further develop the application of ATR-FTIR spectroscopic imaging within the field of protein studies. ATR-FTIR imaging has been applied to study the effects of different conditions for microbatch protein crystallisation in a high throughput manner, where many samples can be analysed at the same time on the surface of a Macro ATR crystal by building a wax grid with multiple wells for different samples. Additionally, Micro ATR-FTIR imaging was combined with hanging drop protein crystallisation for high spatial resolution imaging of the growth of protein crystals. The surface properties of Silicon ATR crystals were modified to create a gradient of hydrophobicity allowing the effect of different surface properties on protein adsorption and crystallisation to be studied in situ. The development of these approaches will advance the use of spectroscopic imaging within the field of biopharmaceuticals, where it is has the potential to help the optimisation of both biopharmaceutical drug discovery processes and structural proteomics studies.
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Gu, Meng. "High-speed volumetric ¹H magnetic resonance spectroscopic imaging /." May be available electronically:, 2008. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.
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Chatnuntawech, Itthi. "Model-based reconstruction of magnetic resonance spectroscopic imaging." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/82376.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2013.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 77-80).
Magnetic resonance imaging (MRI) is a medical imaging technique that is used to obtain images of soft tissue throughout the body. Since its development in the 1970s, MRI has gained tremendous importance in clinical practice because it can produce high quality images of diagnostic value in an ever expanding range of applications from neuroimaging to body imaging to cancer. By far the dominant signal source in MRI is hydrogen nuclei in water. The presence of water at high concentration (-50M) in body tissue, combined with signal contrast modulation induced by the local environment of water molecules, accounts for the success of MRI as a medical imaging modality. As opposed to conventional MRI, which derives its signal from the water component, magnetic resonance spectroscopy (MRS) acquires the magnetic resonance signal from other chemical components, most frequently various metabolites in the brain, but also signals from tumors in breast and prostate. The spectroscopic signal arises from low concentration (-1 - 10mM) compounds, but in spite of the challenges posed by the resulting low signal-to-noise ratio (SNR), the development of MRS is motivated by the desire to directly observe signal sources other than water. The combination of MRS with spatial encoding is called magnetic resonance spectroscopic imaging (MRSI). MRSI captures not only the relative intensities of metabolite signals at each voxel, but also their spatial distributions. While MRSI has been proven to be clinically useful, it suffers from fundamental tradeoffs due to the inherently low SNR, such as long acquisition time and low spatial resolution. In this thesis, techniques that combine benefits from both model-based reconstruction methods and regularized reconstructions with prior knowledge are proposed and demonstrated for MRSI. These methods address constraints on acquisition time in MRSI by undersampling data during acquisition in combination with improved image reconstruction methods.
by Itthi Chatnuntawech.
S.M.
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Yeo, Woon Gi. "Terahertz Spectroscopic Characterization and Imaging for Biomedical Applications." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1430825935.
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Chan, Ka Lung Andrew. "Spectroscopic imaging of polymeric materials and pharmaceutical formulations." Thesis, Imperial College London, 2004. http://hdl.handle.net/10044/1/11974.
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BILHORN, ROBERT BYERS. "ANALYTICAL SPECTROSCOPIC CAPABILITIES OF OPTICAL IMAGING CHARGE TRANSFER DEVICES." Diss., The University of Arizona, 1987. http://hdl.handle.net/10150/184186.
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The investigations described within this dissertation foretell the imminent revolution in optical analytical spectroscopy and conclusively demonstrate superior qualitative and quantitative analysis performance of a new system for atomic spectroscopy as compared to present, state-of-the-art instrumentation. The advent of a new class of multichannel detectors, the silicon charge transfer devices (CTDs) is shown to significantly impact ultraviolet, visible, and near-infrared analytical spectroscopy. An overview of the operation, characteristics, and performance of CTDs is presented including the results of the characteristics of a CTD detector system developed during these investigations. Theoretical comparisons of the performance obtainable in spectroscopic systems employing CTD detectors versus conventional detectors, including equations identifying the factors limiting sensitivity, demonstrate that CTDs offer superior performance. The second part of this dissertation describes the application of a particular CTD, the charge injection device (CID), to a very challenging spectroscopic problem, as far as light detection is concerned, simultaneous multielement analytical atomic emission spectroscopy. This widely employed technique for qualitative and quantitative elemental analysis requires sensitive and wide dynamic range detection of a large number of spectral resolution elements. This research resulted in the development of a novel echelle spectrometer employing a CID detector which has been demonstrated to be capable of solving many of the problems currently encountered in analytical atomic spectroscopy. The system achieves superior sample throughput rates, flexibility, accuracy and precision as compared to sequential spectrometers employing a single detector and to polychromators employing relatively few fixed detectors. The research included the development of a unique method of operating the CID, which is used to cope with the very wide dynamic range signals encountered in atomic spectroscopy, and has resulted in a spectroscopic instrument able to qualify simultaneously major and trace components of extremely complex samples with greater sensitivity and accuracy than possible with conventional instrumentation. New, very flexible, and extremely rapid methods of qualitative analysis have also been developed which virtually eliminate the possibility of spectral line misassignment. The atomic emission spectroscopic system is applicable in a variety of analytical areas as diversified as high sensitivity detection of near infrared spectral lines and element-specific detection of chromatographic eluents.
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Parikh, Jehill. "Measurement of brain temperature using magnetic resonance spectroscopic imaging." Thesis, University of Edinburgh, 2013. http://hdl.handle.net/1842/8082.
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The study of brain temperature is important for a number of clinical conditions such as stroke, traumatic brain injury, schizophrenia and birth asphyxia (for neonates). A direct method to estimate brain temperature non-invasively will allow assessment of brain thermoregulation and its variation in clinical conditions. Magnetic resonance imaging is a powerful technique widely used for diagnosis of a range of neurological conditions. All magnetic resonance procedures involve manipulation of the hydrogen nuclei in the water molecules of the human body. The resonance frequency of the water molecules is temperature dependent, thus MR thermometry is a powerful tool for non-invasive temperature measurement. Using internal reference MR spectroscopic imaging (MRSI), absolute brain temperature maps can be estimated. However a number of temperature independent factors influence MRSI data acquisition, thus a thorough validation is necessary and is the focus of this PhD study. In this PhD study using phantom (test object) studies it was shown that optimization of the MRSI pulse sequence is necessary to reduce systematic error in temperature maps and extensive in-vitro validation of MRSI temperature mapping was performed. A custom made temperature-controlled phantom was designed for this purpose and is presented in this thesis. MRSI data acquired from healthy (young and elderly) volunteers was employed to assess regional brain temperature variations and repeatability. Finally, the feasibility of employing fast echo planar spectroscopic imaging for volumetric MRSI temperature mapping will be presented in this thesis.
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Alkhatib, Fatmah Mohammad. "A spectroscopic and imaging investigation of sporopollenin-metal interactions." Thesis, University of Hull, 2017. http://hydra.hull.ac.uk/resources/hull:16526.
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The main objective has been the determination of the nature of the interaction of metal complexes and salts with the surface of sporopollenin exine capsules (SEC) and other naturally occurring spore exines. These natural materials derived from plant pollen and spores can interact with the inorganic compounds via the formation of coordination bonds and can impart unusual properties. This makes them ideal materials for investigation as they can be used in a wide variety of applications including catalysis, metal remediation, imaging and biological delivery. Although there have been many studies using brown SECs, the focus of this work has been on bleached SECs as the paler colour enables the use of a wider variety of spectroscopic techniques. The first row transition metals copper, iron, nickel, and zinc were used and a selection of spectroscopic techniques (IR, Raman, ICP-OES, UV-Vis, NMR, EPR, Mössbauer and X-ray absorption spectroscopy) were employed to characterise the complexes formed between the metals and the brown and white SECs. Metal loadings of 0.5 to 10 wt% were observed for all the metals and both the brown and bleached SECs. The higher loadings were observed for complexes derived from acetate salts for copper, nickel and zinc. IR spectroscopy of the SECs revealed the presence of aliphatic chains and hydroxyls, aliphatic carbons, carbonyls, unsaturation, ester and ether groups. For the copper, nickel and zinc complexes the IR spectra showed the presence of νCO modes indicating the mode of coordination, and in the acetate complexes there were a significant difference in the spectrum indicating the presence of bound acetate. The IR spectra of the iron complexes were different indicating the presence of a different structural motif. The UV-vis spectra displayed the characteristic features of metal(II) for copper, nickel and zinc, with the spectra of the complexes prepared from chloride and nitrate solutions being essentially identical, but different to that from the acetate solution. There were slight differences between all the spectra of the iron-BL-SEC complexes, with the complex derived from SEC and solution of (NH4)Fe(SO4)2 presenting the highest intensity peak. The 13C NMR solid state spectra of the brown and bleached SECs, as well as those of the zinc complexes showed peaks characteristic of aliphatic, olefinic and aromatic carbon, C-O, carboxylic acid and ester groups. For the zinc acetate with BL-SECs was different in the 35 – 10 ppm aliphatic region compared to that of zinc nitrate and zinc chloride with BL-SEC. However, the spectra were similar for all zinc salts with BR-SECs. The metal K-edge EXAFS data from the nickel and zinc complexes were more similar to the copper data rather than the iron data, indicating the presence of mononuclear octahedral metal complexes for nickel and zinc. For copper, the EXAFS data indicated the presence of a Jahn-Teller distortion for copper, which was confirmed by EPR spectroscopy. In the case of iron the EXAFS data indicated the formation of small oxide or oxyhydroxide particles. The metal K-edge XANES data confirmed the presence of Cu(II), Ni(II) and Zn(II), but indicated that in the case of iron, this was present as Fe(III), which was also consistent with the 57Fe Mössbauer data. mXRF imaging data using synchrotron radiation has shown that the metal distribution in the copper, nickel and zinc complexes is very closely associated with the underlying physical structure of the SEC. The conclusion from all the spectroscopic data is that the most likely source of coordination of the copper, nickel and zinc metals are the carboxylate groups in the sporopollenin structure resulting in monomeric complexes on the sporopollenin surface. The structures of the chloride and nitrate complexes are very similar, but in the case of acetate there is evidence for the presence of acetate ligands in the coordination environment. The higher metal loadings observed for the acetate complexes can be explained by this as the metal does not require so many ligand groups in close proximity on the SEC surface. In the case of iron, the structures appear to be different, and are based on very small clusters of iron oxide or oxyhydroxide particles attached to the SEC surface.
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Sawbridge, Rebecca Joanne. "Developments in magnetic resonance spectroscopic imaging acquisition and analysis." Thesis, University of Birmingham, 2018. http://etheses.bham.ac.uk//id/eprint/8050/.
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Magnetic Resonance Spectroscopic Imaging (MRSI), a functional MR imaging technique, has proven via the identification of metabolite biomarkers to be useful in the diagnosis and prognosis of numerous diseases, for example brain tumours. However, a number of factors impede its routine clinical use: i) long acquisition times mean its use is limited to low resolution 2-dimensional slabs, ii) large quantity of data produced means its interpretation can be time consuming and iii) data quality can be variable and therefore interpretation can be difficult for a non-expert. Further developments in MRSI are designed to reduce the impact of these issues. The focus of this work is to address some of the above issues; developing acquisition protocols and optimising analysis methods in order to increase the clinical feasibility of MRSI. Within this study a fast-MRSI protocol has been developed for absolute metabolite quantitation and has demonstrated its feasibility for clinical use, accurately reproducing data in a shorter clinically feasible acquisition time. An experimentally derived fitting model has been developed which increases metabolite measurement accuracy. Finally, a 3D MRSI protocol has been successfully optimized allowing robust metabolite information to be mapped throughout the brain.
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Gagoski, Borjan Aleksandar. "Fast magnetic resonance spectroscopic imaging using RF coil arrays." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/37930.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2006.Includes bibliographical references (p. 71-73).
Conventional Magnetic Resonance Spectroscopic Imaging (MRSI) suffers from both low signal-to-noise (SNR), as well as long acquisition times. The development of high-fidelity gradient coils has opened opportunities for fast k-space encoding schemes that are already used in structural imaging. At the same time, receive-coil arrays using 4 and 23 channels have been developed and reported to produce improved SNR over conventional quadrature detection by single coils. Fast spectroscopic imaging algorithm using spiral k-space trajectories and multiple-channel coil arrays is proposed in order to overcome the long acquisition-time limitations of conventional MRSI.
by Borjan Aleksandar Gagoski.
S.M.
20
Lee, Joonsung. "Excitation and readout Designs for high field spectroscopic imaging." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/64578.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2011.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 86-90).
In this thesis we state and demonstrate solutions to three engineering problems that arise in magnetic resonance imaging RF excitation with parallel transmission (pTx) and magnetic resonance spectroscopic imaging (MRSI). Recent work in parallel RF excitation in MRI has been demonstrated to offer dramatically improved flexibility for manipulation of magnetization preparation for imaging than is feasible with conventional single-channel transmission. We address two design problems that need to be solved before this emerging technology can be deployed in the clinical and research domain of human imaging at high field. First, we demonstrate a method for rapid and robust acquisition of the non-uniform fields of RF excitation due to arrays that are commonly used in pTx at high field. Our method achieves high-fidelity single-slice excitation and reception field mapping in 20 seconds, and we propose ways to extend this to multi-slice mapping in two minutes for twenty slices. A fundamental constraint to the application of pTx is the management of the deposition of power in human tissue, quantified by the specific absorption rate (SAR). The complex behavior of the spatial distribution of SAR in transmission arrays poses problems not encountered in conventional single-channel systems, and we propose a pTx design method to incorporate local SAR constraints within computation times that accommodate pTx pulse design during MRI acquisition of human subjects. Our approach builds on recent work to capture local SAR distribution with much lower computational complexity than a brute-force evaluation, and we demonstrate that this approach can reduce peak local SAR by 20~40% for commonly applied pTx design targets. This thesis focuses on the design of excitation methods for high field system (7T parallel transmit (pTx) system) and fast readout and post-processing methods to reduce the lipid contamination to the brain. The contributions include fast B1+ mapping and pTx RF pulse design with the local SAR constraints for excitation. Regarding the readout method we developed a real time filter design, variable density spiral trajectory, and iterative non-linear reconstruction technique that reduce the lipid contamination. The proposed excitation methods were demonstrated using a 7T pTx system and the readout methods were implemented in a 3T system. Our third contribution addresses a recurring problem in MRSI of the brain, namely strong contaminating artifacts in low signal-to-noise ratio brain metabolite maps due to subcutaneous, high-concentration lipid sources. We demonstrate two methods to address this problems, one during the acquisition stage where a spatial filter is designed based on spatial priors acquired from the subject being scanned, and the second is a post-processing method that applies the brain and lipid source prior for further artifact minimization. These methods are demonstrated to achieve 20~4OdB enhancement of lipid suppression in brain MRSI of human subjects.
by Joonsung Lee.
Ph.D.
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Boswell, C. J. (Christopher James) 1974. "Visible spectroscopic imaging on the Alcator C-Mod tokamak." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/16600.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 2003.Includes bibliographical references (p. 155-161).
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
This dissertation reports on the development of a diagnostic visible imaging system on the Alcator C-Mod tokamak and the results from that system. The dissertation asserts the value of this system as a qualitative and quantitative diagnostic for magnetically confined plasmas. The visible imaging system consists of six CCD cameras, absolutely calibrated and filtered for specific spectral ranges. Two of these cameras view the divertor region tangentially, two view RF antenna structures and two are used for a wide-angle survey of the vacuum vessel. The divertor viewing cameras are used to generate two-dimensional emissivity profiles using tomography. Three physics issues have been addressed using the visible imaging system: 1) Using two-dimensional emissivity profiles of Da, volumetric recombination rate profiles have been measured and found to have a structure that depends on a poloidal temperature gradient in the outer scrape-off-layer. 2) A camera viewing the inner wall tangentially was used to measure Da emission profiles. A sharp break in slope of the radial density profile was found at the location of the secondary separatrix near the inner wall by using these profiles and a kinetic model of the neutrals. 3) Two-dimensional emissivity profiles of visible continuum (420-430nm) have been measured and found to be an order of magnitude too large when compared to expected levels from electron-ion bremsstrahlung and radiative recombination. Several atomic and molecular processes have been considered to explain the enhanced continuum. However, none of the considered processes could explain the continuum level without particle densities inconsistent with current modeling efforts.
(cont.) The visible imaging system was also used in identifying the causes of impurity injections during discharges, in identifying the failure of invessel components, and as a monitor of vessel and plasma conditions. Both the physics results and the operational benefits of the visible imaging system show that the system is a valuable quantitative and qualitative diagnostic.
by Christopher James Boswell.
Ph.D.
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Gagoski, Borjan Aleksandar. "Magnetic resonance spectroscopic imaging using parallel transmission at 7T." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/63069.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2011.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 123-130).
Conventional magnetic resonance spectroscopic imaging (MRSI), also known as phase-encoded (PE) chemical shift imaging (CSI), suffers from both low signal-to-noise ratio (SNR) of the brain metabolites, as well as inflexible tradeoffs between acquisition time and spatial resolution. In addition, although CSI at higher main field strengths, e.g. 7 Tesla (T), offers improved SNR over clinical 1.5T or 3.OT scanners, the realization of these benefits is limited by severe inhomogeneities of the radio frequency (RF) excitation magnetic field (B,+), which is responsible for significant signal variation within the volume of interest (VOI) resulting in spatially dependent SNR losses. The work presented in this dissertation aims to provide the necessary means for using spectroscopic imaging for reliable and robust whole brain metabolite detection and quantification at high main field strengths. It addresses the challenges mentioned above by improving both the excitation and the readout components of the CSI acquisition. The long acquisition times of the PE CSI are significantly shortened (at least 20 fold) by implementing the time-efficient spiral CSI algorithm, while the B1 non-uniformities are corrected for using RF pulses designed for new RF excitation hardware at 7T, so-called parallel transmission (pTx). The B1 homogeneity of the pTx excitations improved at least by a factor of 4 (measured by the normalized spatial standard deviations) compared to conventional single channel transmit systems. The first contribution of this thesis describes the implementation of spiral CSI algorithm for online gradient waveform design and spectroscopic image reconstruction with standard clinical excitation protocols and applied in studies of Late-Onset Tay- Sachs (LOTS), adrenoleukodystrophy (ALD) and brain tumors. A major contribution of this thesis is pTx excitation design for CSI to provide spectral-spatial mitigation of the B1+ inhomogeneities at 7T. Novel pTx RF designs are proposed and demonstrated to yield excellent flip angle mitigation of the brain metabolites, and also enable improved suppression of the undesired water and lipid signals. A major obstacle to the deployment of 7T pTx applications for clinical imaging is the monitoring and management of local specific absorption rate (SAR). This thesis also proposes a pTx SAR monitoring system with real-time RF monitoring and shut-off capabilities.
by Borjan Aleksandar Gagoski.
Ph.D.
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Wild, James Michael. "Proton magnetic resonance spectroscopic imaging of the human brain." Thesis, University of Edinburgh, 1998. http://hdl.handle.net/1842/22742.
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Over the last ten years proton NMR spectroscopy has been performed on clinical MRI scanners using single voxel localisation and spectroscopic imaging sequences. In this work inner volume excitation of a transverse imaging plane within the brain has been used to obtain single slice spectroscopic images of proton metabolites. The existing image processing protocols used to construct the metabolite images were improved and optimised so as to give as accurate a picture of metabolite distribution as possible. Inaccuracy in these images can be introduced by the excitation profile of the radio frequency pulses used in inner volume excitation. A new normalisation technique is proposed which will remove these inaccuracies enabling more reliable quantification of metabolite concentrations. Of particular importance in stroke is the metabolite lactate, elevated levels of which are symptomatic with the conditions of anaerobic glycolysis that are thought to precede infarction. The signal from lactate is often obscured by lipid and macro-molecule resonances in the same frequency range. Lactate editing sequences compatible with the hardware capabilities of the scanner and spectroscopic imaging sequences were investigated for viability in-vivo. Using two different editing sequences lactate editing was performed successfully in vitro and in vivo. In-vivo results are presented from a study of 40 stroke patients and a smaller pilot study of 8 head injury patients. These patients were drawn from the Lothian Stroke Register as part of the Clinical Research Initiative (CRI) in stroke and head injury being co-ordinated at the Western General Hospital, Edinburgh. To our knowledge this is the largest proton spectroscopic study of acute stroke patients and as such should have a significant bearing in analysing the physiological implications of the disease.
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Chen, Wen-Lung. "Raman spectroscopic/imaging studies of eye lenses and lens proteins." Diss., Georgia Institute of Technology, 1991. http://hdl.handle.net/1853/30431.
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Malamas, Sitthichai. "Spectroscopic imaging with uncooled microbolometer camera and step-scan FTIR." Thesis, Monterey, Calif. : Naval Postgraduate School, 2006. http://bosun.nps.edu/uhtbin/hyperion.exe/06Dec%5FMalamas.pdf.
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Thesis (M.S. in Applied Physics)--Naval Postgraduate School, December 2006.Thesis Advisor(s): Gamani Karunasiri, D. Scott Davis. "December 2006." Includes bibliographical references (p. 37). Also available in print.
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Earnhart, Jonathan Raby. "A Compton Camera for Spectroscopic Imaging from 100keV to 1MeV." NCSU, 1999. http://www.lib.ncsu.edu/theses/available/etd-19990507-170013.
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Earnhart, Jonathan Raby Dewitt. A Compton Camera for Spectroscopic Imaging from 100keV to 1MeV (Under the direction of Robin Gardner and Thomas Prettyman).
Compton cameras are a particularly interesting gamma-ray imaging technology because they have a large field of view and rely on electronic rather than mechanical collimation (lead). These systems produce two dimensional, spectroscopic images using data collected from spatially separated detector arrays. A single acquisition contains data to produce image signatures for each radionuclide in the field of view. Application of Compton cameras in field of astrophysics has proven the systems capability for imaging in the 1 to 30MeV range. Other potential applications, in the 100keV to 1MeV range, include nuclear material safeguards and nuclear medicine imaging. A particularly attractive feature for these applications is that the technology to produce a portable camera is now available due to improvements in solid state room-temperature detectors.
The objective of this work is to investigate Compton camera technology for spectroscopic imaging of gamma rays in the 100keV to 1MeV range. To this end, accurate and efficient camera simulation capability will allow a variety of design issues to be explored before a full camera system is built. An efficient, specific purpose Monte Carlo code was developed to investigate the image formation process in Compton cameras. The code is based on a pathway sampling technique with extensive use of variance reduction techniques. In particular, the technique of forcing is used make each history result in a partial success. The code includes detailed Compton scattering physics, including incoherent scattering functions, Doppler broadening, and multiple scattering. Detector response functions are also included in the simulations.
A prototype camera was built to provide code benchmarks and investigate implementation issues. The prototype is based on a two-detector system, which sacrifices detection efficiency for simplicity and versatility. One of the detectors is mounted on a computer controlled stage capable of two dimensional motion (14x14cm full range with ±0.1mm precision). This produces a temporally encoded image via motion of the detector.
Experiments were performed with two different camera configurations for a scene containing a 75Se source and a 137Cs source. These sources provided a challenging test of the spectroscopic imaging capability of the Compton camera concept. The first camera was based on a fixed silicon detector in the front plane and a CdZnTe detector mounted in the stage. The second camera configuration was based on two CdZnTe detectors. Both systems were able to reconstruct images of 75Se, using the 265keV line, and 137Cs, using the 662keV line. Only the silicon-CdZnTe camera was able to resolve the low intensity 400keV line of 75Se. Neither camera was able to reconstruct the 75Se source location using the 136keV line. The camera has a low energy limit imposed by the noise level on the front plane detector's timing signal. The timing performance of the coplanar grid CdZnTe detector design was improved, resulting in a reduction in the full width half maximum of the coincidence timing peak between two detectors from 800ns to 30ns.
The energy resolution of the silicon-CdZnTe camera system was 4% at 662keV. This camera reproduced the location of the 137Cs source by event circle image reconstruction with angular resolutions of 10° for a source on the camera axis and 14° for a source 30° off axis. The source to camera distance was approximately 1m. Typical detector pair efficiencies were measured as 3x10-11 at 662keV.
The dual CdZnTe camera had an energy resolution of 3.2% at 662keV. This camera reproduced the location of the 137Cs source by event circle image reconstruction with angular resolutions of 8° for a source on the camera axis and 12° for a source 20° off axis. The source to camera distance was 1.7m. Typical detector pair efficiencies were measured as 7x10-11 at 662keV.
Of the two prototype camera configurations tested, the silicon-CdZnTe configuration had superior imaging characteristics. This configuration is less sensitive to effects caused by source decay cascades and random coincident events. An implementation of the expectation maximum-maximum likelihood reconstruction technique improved the angular resolution to 6° and reduced the background in all the images.
The measured counting rates were a factor of two low for the silicon-CdZnTe camera, and up to a factor of four high for the dual CdZnTe camera compared to simulation. These differences are greater than the error bars. The primary reasons for these discrepancies are related to experimental conditions imposed by source decay cascades and the occurrence of random coincidences which are not modeled by the code.
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Woods, Stephan M. "VIBRATIONAL SPECTROSCOPY AND SPECTROSCOPIC IMAGING OF BIOLOGICAL CELLS AND TISSUE." Kent State University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=kent1322540287.
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Kimber, James A. "Mathematical modelling and FTIR spectroscopic imaging of pharmaceutical tablet dissolution." Thesis, Imperial College London, 2012. http://hdl.handle.net/10044/1/9301.
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The process of pharmaceutical tablet dissolution is a vital stage in the delivery of active pharmaceutical ingredients (APIs). The constituent components and their spatial arrangement within the tablet determine the release characteristics of the API. It is therefore important to understand and characterise the various processes and component interactions that occur during tablet dissolution. Computational simulations of tablet dissolution can be used to obtain parametric sensitivities and optimise formulations so that the desired API release profile is achieved. This thesis describes the methods behind modelling the behaviour of non-swelling and swelling tablets, the mathematical validation of the models, parametric studies and the experiments which were used to obtain parameters and verify the models. The experimental method used in this work is Fourier Transform Infrared (FTIR) spectroscopic imaging, which, when using an attenuated total reflection (ATR) accessory and flow cell, enable chemical and spatial information to be obtained from the tablet as it dissolves. UV/Visible spectroscopy was also used to obtain drug release information. The non-swelling model discretised a tablet over a Cartesian grid and solved the mass transfer equations (dissolution and diffusion) to obtain drug release profiles. Two parametric studies were conducted where the particle size distribution and mass fractions were varied in one, and the API diffusivity, saturated concentration and mass fraction in the other to see what effect these had on drug release, demonstrating the importance of the choice of excipient and the impact of particle size on release variability. For experimental validation, tablets containing different quantities of polyethylene glycol and nicotinamide were dissolved and imaged, and optimisation was used to obtain the pure component saturated concentrations. The model was then tested against a different tablet to demonstrate the predictive capability of the model. The swelling model discretised a tablet into small cylindrical particles, whose size was proportional to the mass of components within them and whose motion was determined using the Discrete Element Method (DEM). As water diffused into polymer particles, they could expand, resulting in macroscopic swelling. The DEM model of a swelling and dissolving tablet was validated against a numerically exact model of the same tablet and parametric studies were conducted into the effect of polymer disentanglement threshold, polymer equilibrium water fraction and polymer dissolution rate. The model was also optimised against a dissolving tablet containing HPMC to obtain parameters for this excipient. To conclude, both models were implemented, validated and found to accurately describe the dissolution kinetics of both swelling and non-swelling tablets.
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Li, Yan. "Multi-dimensional MR spectroscopic imaging of gliomas at different field strengths." Diss., Search in ProQuest Dissertations & Theses. UC Only, 2008. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3311329.
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Thesis (Ph.D.)--University of California, San Francisco with the University of California, Berkeley, 2008.Source: Dissertation Abstracts International, Volume: 69-06, Section: B, page: 3694. Adviser: Sarah J. Nelson.
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Ewing, Andrew. "ATR-FTIR spectroscopic imaging to study drug release and tablet dissolution." Thesis, Imperial College London, 2016. http://hdl.handle.net/10044/1/51556.
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The active pharmaceutical ingredient (API) and excipients are vital for determining the behaviour of drug release from tablet compacts. Macro attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopic imaging can be employed for in situ studies of dissolving tablets. This thesis describes new developments that applied macro ATR-FTIR spectroscopic imaging to investigate the stability and dissolution of amorphous APIs, the effect of carriers for improving drug release, the stability of ionised drug candidates and the behaviour of multiple formulations in microfluidic devices. Solid dispersions containing an amorphous drug formulated with different polymers were investigated using ATR-FTIR spectroscopy and spectroscopic imaging. Crystallisation of the amorphous drug was detected during stability and tablet dissolution experiments. The implications of this form change inhibited dissolution of the drug into solution. ATR-FTIR spectroscopic imaging was also used in combination with ultraviolet detection to study the release of a drug formulated with selected carriers. Hydrogen bonded interactions between the drug and carrier were characterised and resulted in an increased rate of drug release. When these interactions were not present in the tablet, a slower rate of dissolution was observed. Disproportionation of an ionised drug was investigated by ATR-FTIR spectroscopic imaging and Raman mapping. During dissolution experiments in acidic solution, chemical changes of the ionised API were detected in real time that resulted in the formation of the less soluble form of the drug. Exciting results were obtained by simultaneously screening the behaviour of multiple formulations in microfluidic channels using macro ATR-FTIR spectroscopic imaging. Moreover, the precipitation of a dissolved drug that crystallised upon contact with an acidic solution was investigated. Overall, the research in this thesis has demonstrated that macro ATR-FTIR spectroscopic imaging can address the challenges of studying a range of innovative delivery systems that can ultimately lead to the development of more efficient pharmaceutical formulations.
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Worthington, Lara Angharad. "Investigation of compressed-sensing for acceleration of magnetic resonance spectroscopic imaging." Thesis, University of Birmingham, 2015. http://etheses.bham.ac.uk//id/eprint/6128/.
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Magnetic Resonance Spectroscopic Imaging (MRSI) is a functional MRI technique allowing non-invasive biochemical mapping of the brain. MRSI is advantageous for characterising many neurological conditions; however, its clinical application is limited by lengthy scan time and low spatial resolution, which are intrinsically linked. This research investigated the potential of Compressed Sensing (CS) to speed-up MRSI or enhance spatial resolution. CS allows accelerated acquisition by reducing the data sampling requirements, whilst preserving image quality. The focus of this work was the effect of CS-MRSI at different acceleration factors upon spatial integrity. CS reconstruction software was developed and applied to retrospective MRSI data. Imaging test objects and software simulations were developed to assess MRSI spatial resolution via metabolite edge response measurements. CS-MRSI was also investigated in realistic scenarios using data from healthy volunteers and a child with Optic Pathway Glioma (OPG). The potential of CS-MRSI to enable high-resolution MRSI in feasible scan times was investigated using simulations of focal and infiltrative OPG. Results suggest that CS-MRSI can reduce scan duration by up to a factor of 5 whilst simultaneously eliminating ringing artefacts and increasing spatial resolution compared with conventionally filtered MRSI. Therefore, CS could greatly increase the clinical utility of MRSI.
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Ferguson, Leesa Susanne. "Analysis of the composition of latent fingermarks by spectroscopic imaging techniques." Thesis, Sheffield Hallam University, 2013. http://shura.shu.ac.uk/19645/.
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Despite the success of DNA fingerprinting, fingermarks remain an efficient means of ascertaining the identity of an individual at many crime scenes. There are numerous enhancement techniques used to develop fingermarks on a range of deposition surfaces. Despite this, there is a need for further intelligence to be gained in situations where fingermarks retrieved at crime scenes do not yield identification. The majority of the work presented in this thesis utilises MALDI mass spectrometry in profiling and imaging mode to investigate latent fingermarks, with SERS and ATR-FTIR used as complementary techniques. One of the major issues of using analytical techniques to investigate latent fingermarks is their inadequate application to real crime scene scenarios. Presented within this thesis is a new method of matrix application that makes MALDI-MSI forensically applicable and enables the distribution of various endogenous lipids and exogenous compounds within fingermarks to be visualised. The work is extended to include detection of various antimicrobial peptides and small proteins in the fingermarks of a cohort of 80 donors using MALDI mass spectrometry profiling followed by multivariate statistical analysis in an attempt to differentiate donors based on their sex. Chemical imaging of latent fingermarks by SERS and ATR-FTIR is also demonstrated, which could potentially lead to a three step multi-informative analytical approach for chemical characterisation of fingermark residue.
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Laruelo, Fernandez Andrea. "Integration of magnetic resonance spectroscopic imaging into the radiotherapy treatment planning." Thesis, Toulouse 3, 2016. http://www.theses.fr/2016TOU30126/document.
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L'objectif de cette thèse est de proposer de nouveaux algorithmes pour surmonter les limitations actuelles et de relever les défis ouverts dans le traitement de l'imagerie spectroscopique par résonance magnétique (ISRM). L'ISRM est une modalité non invasive capable de fournir la distribution spatiale des composés biochimiques (métabolites) utilisés comme biomarqueurs de la maladie. Les informations fournies par l'ISRM peuvent être utilisées pour le diagnostic, le traitement et le suivi de plusieurs maladies telles que le cancer ou des troubles neurologiques. Cette modalité se montre utile en routine clinique notamment lorsqu'il est possible d'en extraire des informations précises et fiables. Malgré les nombreuses publications sur le sujet, l'interprétation des données d'ISRM est toujours un problème difficile en raison de différents facteurs tels que le faible rapport signal sur bruit des signaux, le chevauchement des raies spectrales ou la présence de signaux de nuisance. Cette thèse aborde le problème de l'interprétation des données d'ISRM et la caractérisation de la rechute des patients souffrant de tumeurs cérébrales. Ces objectifs sont abordés à travers une approche méthodologique intégrant des connaissances a priori sur les données d'ISRM avec une régularisation spatio-spectrale. Concernant le cadre applicatif, cette thèse contribue à l'intégration de l'ISRM dans le workflow de traitement en radiothérapie dans le cadre du projet européen SUMMER (Software for the Use of Multi-Modality images in External Radiotherapy) financé par la Commission européenne (FP7-PEOPLE-ITN)The aim of this thesis is to propose new algorithms to overcome the current limitations and to address the open challenges in the processing of magnetic resonance spectroscopic imaging (MRSI) data. MRSI is a non-invasive modality able to provide the spatial distribution of relevant biochemical compounds (metabolites) commonly used as biomarkers of disease. Information provided by MRSI can be used as a valuable insight for the diagnosis, treatment and follow-up of several diseases such as cancer or neurological disorders. Obtaining accurate and reliable information from in vivo MRSI signals is a crucial requirement for the clinical utility of this technique. Despite the numerous publications on the topic, the interpretation of MRSI data is still a challenging problem due to different factors such as the low signal-to-noise ratio (SNR) of the signals, the overlap of spectral lines or the presence of nuisance components. This thesis addresses the problem of interpreting MRSI data and characterizing recurrence in tumor brain patients. These objectives are addressed through a methodological approach based on novel processing methods that incorporate prior knowledge on the MRSI data using a spatio-spectral regularization. As an application, the thesis addresses the integration of MRSI into the radiotherapy treatment workflow within the context of the European project SUMMER (Software for the Use of Multi-Modality images in External Radiotherapy) founded by the European Commission (FP7-PEOPLE-ITN framework)
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Wray, Patrick S. "Spectroscopic imaging of the compaction and dissolution of model pharmaceutical formulations." Thesis, Imperial College London, 2011. http://hdl.handle.net/10044/1/9074.
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Orally administered compressed tablets are the most commonly used dosage form. Understanding the physical and chemical processes involved in drug release from tablets is critical for designing more effective formulations. Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR) spectroscopic imaging is a powerful chemically specific and spatially resolved analytical approach. Effective uses for this technology have been found in the field of pharmaceutics, studying the compaction and dissolution of oral dosage formulations. However, the full potential of this technology is yet to be explored. This thesis describes work that further explores the applications of FTIR imaging through the use of model pharmaceutical formulations. The work is broadly split into three sections: quantification of imaging data, dissolution of pH modified formulations and application to structured tablets. The in situ compaction of model drug tablets with different polymer matrices was studied using ATR-FTIR imaging. The choice of polymer strongly affected the distribution of the drug at the tablet surface. X-ray tomography was used as a complementary technique, verifying the distribution of drug particles within the compacted matrices. Statistical analysis was applied to investigate obtaining quantitative data such as particle size and component loading from the image data. Previous work using ATR-FTIR imaging has shown the ability of the approach to detect crystallisation of ibuprofen during dissolution. The dissolution of ibuprofen from HPMC matrices containing pH modifying compounds was studied. FTIR imaging showed that tablets containing acidic compounds slowed the dissolution of crystalline ibuprofen domains. The formation of soluble and insoluble salts of the drug was seen in tablets containing basic compounds. As FTIR imaging supplies both chemical and spatial information it was applied to study structured tablets, both tablet-in-tablet structures and multilayer formulations, in conjunction with visible optical video analysis. The tablet-in-tablet structures were used to create delayed release formulations, in which both the core and shell materials were used to control release. pH resistant formulations were also developed for the release of pH labile drugs. FTIR imaging supplied vital information on the rate of ingress of water fronts, the movement of swelling polymers and the chemical state of the drug. Multilayer formulations were investigated for studies of biphasic release and also in order to compare the dissolution performance of tablets in the custom ATR flow cell with that found in the industry standard USP tests.
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Müller, Christoph Alexander [Verfasser], and Jürgen [Akademischer Betreuer] Hennig. "Real-time metabolic imaging of pyruvate and lactate using hyperpolarised 13C magnetic resonance spectroscopic imaging with ME-bSSFP : : a method of clinical cancer imaging." Freiburg : Universität, 2020. http://d-nb.info/1226091237/34.
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Smith, P. G. R. "Spectroscopic and imaging aspects of degenerate four-wave mixing for combustion diagnostics." Thesis, University of Oxford, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239399.
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Gu, Min. "Raman Mode-Selective Spectroscopic Imaging of Redox State in FMN and Flavoprotein." Bowling Green State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1398866391.
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Hu, Simon. "Hyperpolarized carbon-13 magnetic resonance spectroscopic imaging: Pulse sequence development for compressed sensing rapid imaging and preclinical liver studies." Diss., Search in ProQuest Dissertations & Theses. UC Only, 2009. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3390048.
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Thesis (Ph.D.)--University of California, San Francisco with the University of California, Berkeley, 2009.Source: Dissertation Abstracts International, Volume: 71-02, Section: B, page: . Adviser: Daniel B. Vigneron.
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Gudmundson, Erik. "Signal Processing for Spectroscopic Applications." Doctoral thesis, Uppsala universitet, Avdelningen för systemteknik, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-120194.
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Spectroscopic techniques allow for studies of materials and organisms on the atomic and molecular level. Examples of such techniques are nuclear magnetic resonance (NMR) spectroscopy—one of the principal techniques to obtain physical, chemical, electronic and structural information about molecules—and magnetic resonance imaging (MRI)—an important medical imaging technique for, e.g., visualization of the internal structure of the human body. The less well-known spectroscopic technique of nuclear quadrupole resonance (NQR) is related to NMR and MRI but with the difference that no external magnetic field is needed. NQR has found applications in, e.g., detection of explosives and narcotics. The first part of this thesis is focused on detection and identification of solid and liquid explosives using both NQR and NMR data. Methods allowing for uncertainties in the assumed signal amplitudes are proposed, as well as methods for estimation of model parameters that allow for non-uniform sampling of the data. The second part treats two medical applications. Firstly, new, fast methods for parameter estimation in MRI data are presented. MRI can be used for, e.g., the diagnosis of anomalies in the skin or in the brain. The presented methods allow for a significant decrease in computational complexity without loss in performance. Secondly, the estimation of blood flow velo-city using medical ultrasound scanners is addressed. Information about anomalies in the blood flow dynamics is an important tool for the diagnosis of, for example, stenosis and atherosclerosis. The presented methods make no assumption on the sampling schemes, allowing for duplex mode transmissions where B-mode images are interleaved with the Doppler emissions.
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Popa, Emil Horia. "Algorithms for handling arbitrary lineshape distortions in Magnetic Resonance Spectroscopy and Spectroscopic Imaging." Phd thesis, Université Claude Bernard - Lyon I, 2010. http://tel.archives-ouvertes.fr/tel-00716176.
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Magnetic Resonance Spectroscopy (MRS) and Spectroscopic Imaging (MRSI) play an emerging role in clinical assessment, providing in vivo estimation of disease markers while being non-invasive and applicable to a large range of tissues. However, static magnetic field inhomogeneity, as well as eddy currents in the acquisition hardware, cause important distortions in the lineshape of acquired NMR spectra, possibly inducing significant bias in the estimation of metabolite concentrations. In the post-acquisition stage, this is classically handled through the use of pre-processing methods to correct the dataset lineshape, or through the introduction of more complex analytical model functions. This thesis concentrates on handling arbitrary lineshape distortions in the case of quantitation methods that use a metabolite basis-set as prior knowledge. Current approaches are assessed, and a novel approach is proposed, based on adapting the basis-set lineshape to the measured signal.Assuming a common lineshape to all spectral components, a new method is derived and implemented, featuring time domain local regression (LOWESS) filtering. Validation is performed on synthetic signals as well as on in vitro phantom data. Finally, a completely new approach to MRS quantitation is proposed, centred on the use of the compact spectral support of the estimated common lineshape. The new metabolite estimators are tested alone, as well as coupled with the more common residual-sum-of-squares MLE estimator, significantly reducing quantitation bias for high signal-to-noise ratio data.
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Mehta, Manoj. "Spectroscopic imaging and molecular profiling of atherosclerosis : an insight into the aortic condition." Thesis, Imperial College London, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.412529.
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Findlay, Joanna Edyta. "Phase transitions and mesophases in molecular liquids and solutions : spectroscopic and imaging studies." Thesis, University of Glasgow, 2017. http://theses.gla.ac.uk/8531/.
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Liquids are the primary medium for chemical and biological reactions. Phase transitions can give rise to phase separation through nucleation or spinodal decomposition. This phase separation may be the reason behind structure in many liquids, which then has an effect on more practical processes. Mesoscopic (1 nm-1 μm) structuring of the liquid in the neighbourhood of a second critical point associated with a liquid-liquid transition (LLT) can cause anisotropic diffusion, which greatly affects the wetting properties of the liquid. It may also segregate reactants and products, affecting reaction rates and outcomes. Some examples of processes, which may be affected by this, include the synthesis and preparation of pharmaceutical drugs (which is sensitive to liquid structure, phase separation, and nucleation), preparation of nanometre scale materials, electrochemistry, dye-based solar cells, separation technology, and heterogeneous catalysis. This thesis concentrates on advancing of the understanding of some of the phase transitions and mesophases occurring in liquids. The first two chapters are introductory and the remaining chapters describe original research. Chapter 3 describes our studies on crystal nucleation in the presence of a liquid-liquid phase separation. The subjects of these studies were two binary liquid systems: nitrobenzene-hexane and water-1,2-trans-dichloroethylene. Our discovery of template-less asymmetric water crystals (water fluff), which we were able to reproduce repeatedly, strongly suggests that, despite common belief, high driving force does not necessarily lead to ill-defined crystalline forms. We also propose that crystal templating induced by liquid-liquid phase separation might be a general phenomenon, not limited to water. In Chapter 4 we explore one of the most interesting and challenging postulates in the field of liquid science, that is the existence of more than one isotropic liquid states in a single-component liquid at constant temperature and an LLT between these different states. By employing a number of experimental techniques, some of them not previously used to study this subject, we provide a new evidence for the existence of the LLT in triphenyl phosphite (TPP). Furthermore we answer an important and fundamental question of what is the order parameter characterising the LLT in TPP. Finally, Chapter 5 shows how our investigations into the existence of the LLT in n-butanol led to the conclusion that the observed phenomenon is in fact a transition between a supercooled isotropic liquid and a liquid-crystalline (LC) state. The LC is in general considered a form of matter “in between” the liquid and the crystal. However, the LC phase in n-butanol geometrically frustrated the formation of the stable crystalline phase. This frustrated phase can be seen as a template for similar ordering in other molecular liquids and is likely to be essential in their supercooling and LLTs.
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Kok, Trina. "Magnetic resonance spectroscopic imaging with 2D spectroscopy for the detection of brain metabolites." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/78450.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2012.Cataloged from PDF version of thesis. Page 94 blank.
Includes bibliographical references (p. 87-93).
While magnetic resonance imaging (MRI) derives its signal from protons in water, additional biochemical compounds are detectable in vivo within the proton spectrum. The detection and mapping of these much weaker signals is known as magnetic resonance spectroscopy or spectroscopic imaging. Among the complicating factors for this modality applied to human clinical imaging are limited chemical-shift dispersion and J-coupling, which cause spectral overlap and complicated spectral shapes that limit detection and separation of brain metabolites using MR spectroscopic imaging (MRSI). Existing techniques for improved detection include so-called 2D spectroscopy, where additional encoding steps aid in the separation of compounds with overlapping chemical shift. This is achieved by collecting spectral data over a range of timing parameters and introducing an additional frequency axis. While these techniques have been shown to improve signal separation, they carry a penalty in scan time that is often prohibitive when combined with MRSI. Beyond scan time constraints, the lipid signal contamination from the subcutaneous tissue in the head pose problems in MRSI. Due to the large voxel size typical in MRSI experiments, ringing artifacts from lipid signals become more prominent and contaminate spectra in brain tissue. This is despite the spatial separation of subcutaneous and brain tissue. This thesis first explores the combination of a 2D MRS method, _Constant Time Point REsolved SpectroScopy (CT-PRESS) with fast spiral encoding in order to achieve feasible scan times for human in-vivo scanning. Human trials were done on a 3.OT scanner and with a 32-channel receive coil array. A lipid contamination minimization algorithm was incorporated for the reduction of lipid artifacts in brain metabolite spectra. This method was applied to the detection of cortical metabolites in the brain and results showed that peaks of metabolites, glutamate, glutamine and N-acetyl-aspartate were recovered after successful lipid suppression. The second task of this thesis was to investigate under-sampling in the indirect time dimension of CT-PRESS and its associated reconstruction with Multi-Task Bayesian Compressed Sensing, which incorporated fully-sampled simulated spectral data as prior information for regularization. It was observed that MT Bayesian CS gave good reconstructions despite simulated incomplete prior knowledge of spectral parameters.
by Trina Kok.
Ph.D.
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Bhattacharya, Ipshita. "Pushing the limits of spectroscopic imaging using novel low-rank based reconstruction algorithm." Diss., University of Iowa, 2017. https://ir.uiowa.edu/etd/6058.
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Non-invasively reosolving spatial distribution of tissue metabolites serves as a diagnostic tool to in-vivo metabolism thus making magnetic resonance spectroscopic imaging (MRSI) a very useful application. The tissue concentrations of various metabolites reveal disease state and pseudo-progression of tumors. Also, bio-chemical changes manifest much earlier than structural changes that are achieved using standard magnetic resonance imaging(MRI). However, MRSI has not achieved its potential due to several technical challenges that are specic to it. Several technical advances in the eld of MRI does not translate to MRSI. The specic limitations which make MRSI challenging include long scan times, poor spatial resolution, extremely low signal to noise ratio (SNR). In the last few decades, research in MRSI has focused on advanced data acquisition and reconstruction methods, however they cannot achieve high resolution and feasible scan time. Moreover there are several artifacts that lead to increase of spatial resolution not to mention starved SNR. Existing methods cannot deal with these limitations which considerably impacts applications of MRSI. This thesis work we revisit these problems and introduce data acquisition and reconstruction techniques to address several such challenges.
In the first part of the thesis we introduce a variable density spiral acquisition technique which achieves high SNR corresponding to metabolites of interest while reducing truncation artifacts. Along with that we develop a novel compartmentalized reconstruction framework to recover high resolution data from lipid unsuppressed data. Avoiding lipid suppression not only reduces scan time and reliability but also improves SNR which is otherwise reduced even further with existing lipid suppression methods. The proposed algorithm exploits the idea that the lipid and metabolite compartment reside in low-dimensional subspace and we use orthogonality priors to reduce overlap of subspaces.
We also look at spectral artifacts like Nyquist ghosting which is a common problem with spectral interleaving. Especially in echo-planar spectroscopic imaging (EPSI), one of the most popular MRSI techniques, maintaining a spatial and spectral resolution requires interleaving. Due to scanner inconsistencies spurious peaks arise which makes quantication inecient. In this thesis a novel structural low-rank prior is used to reduce and denoise spectra and achieve high resolution ESPI data.
Finally we look at accelerating multi-dimensional spectroscopic problems. Resolving spectra in two dimensions can help study overlapping spectra and achieve more insight. However with an increased dimension the scan time increases. We developed an algorithm for accelerating this method by recovering data from undersampled measurements. We demonstrate the performance in two applications, 2D infra red spectroscopy and 2D MR spectroscopy .
The aim of the thesis is to solve these challenges in MRSI from a signal processing perspective and be able to achieve higher resolution data in practical scan time to ultimately help MRSI reach its potential.
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Foose, Daniel Patrick. "Vespucci: A free, cross-platform software tool for spectroscopic data analysis and imaging." Wright State University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=wright1472823712.
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Silwal, Achut Prasad. "Raman Spectroscopic Imaging Analysis of Signaling Proteins and Protein Cofactors in Living Cells." Bowling Green State University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1528721394633565.
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Langri, Dharminder Singh. "Monitoring Cerebral Functional Response using sCMOS-based High Density Near Infrared Spectroscopic Imaging." Wright State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=wright1558610822306817.
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Heffer, Erica Leigh. "Frequency-domain optical mammography for detection and oximetry of breast tumors /." Thesis, Connect to Dissertations & Theses @ Tufts University, 2004.
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Thesis (Ph.D.)--Tufts University, 2004.Adviser: Sergio Fantini. Submitted to the Dept. of Electrical Engineering. Includes bibliographical references (leaves 201-202). Access restricted to members of the Tufts University community. Also available via the World Wide Web;
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Gendrin, Christelle Hirsch Ernest. "Chemical imaging and chemometrics for the analysis of pharmaceutical solid dosage forms." Strasbourg : Université de Strasbourg, 2009. http://eprints-scd-ulp.u-strasbg.fr:8080/1031/01/GENDRIN_Christelle_2008.pdf.
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Gendrin, Christelle. "Chemical imaging and chemometrics for the analysis of pharmaceutical solid dosage forms." Université Louis Pasteur (Strasbourg) (1971-2008), 2008. https://publication-theses.unistra.fr/public/theses_doctorat/2008/GENDRIN_Christelle_2008.pdf.
Full textAbstract:
Des systèmes d'imagerie hyperspectrale ont été mis sur le marché pour l'analyse chimique microscopique et macroscopique. Constitués d'un détecteur plan présentant une matrice de pixels, ou d'un détecteur point lié à une plateforme mobile, ils peuvent acquérir des spectres localisés spatialement [. . . ]. Les données générées ont donc deux dimensions spatiales et une dimension spectrale, formant ainsi un cube de données. Elles permettent à la fois l'identification des constituants des échantillons et la visualisation de leur distribution spatiale. L'industrie pharmaceutique s'est vivement intéressée à ce nouveau mode d'analyse chimique. En effet, l'homogénéité des différents constituants est essentielle pour la qualité globale des comprimés pharmaceutiques. Par exemple, un mélange non homogène peut engendrer des problèmes au niveau de la production des comprimés comme une adhérence de la poudre sur les poinçons de la presse, ou produire des comprimés n'ayant pas la quantité nominale en Principe Actif (PA), la molécule soignant la maladie, ou encore amener des différences de dissolution et donc influencer l'efficacité du principe actif. De plus, depuis 2002, l'administration américaine imposant les normes de qualité sur les produits pharmaceutiques et alimentaires, La Food and Drug Administration (FDA), promeut la mise en place d'outils de suivi de la production et de contrôle qualité tout au long de la chaîne de fabrication, lançant ainsi l'initiative PAT (Process Analytical Technology). Afin d'améliorer la qualité de leur production et de diminuer le nombre de lots rejetés, les industries pharmaceutiques suivent aujourd'hui ces instructions et tendent à implémenter des nouveaux outils de contrôle. Pour ces raisons, les systèmes d'imagerie chimique non destructifs ont toute leur place dans l'industrie pharmaceutique. . . [etc]By combining both spectral and spatial information Near Infrared Chemical Imaging (NIR-CI) allows the identification of the chemical species and their localization. Since the distribution of chemical species influences greatly the quality attributes of the medicine this kind of instrumentation has naturally shown to be very useful for the development of pharmaceutical products. However, each analysis generates thousands of spatially resolved spectra which need to be processed for objective comparison of the data. In the present work, the extraction of distribution maps and their characterization is firstly addressed. In that case the samples' composition is fully known and specific wavelengths or the full reference spectra are used to localize the chemical species. Histogram analysis is performed to assess the homogeneity of the first intermediates revealing a batch with greater inhomogeneity. In the second intermediates, a difference in the particle sizes of two batches is enhanced using a segmentation scheme based on Otsu thresholding and watershed refinement. The usefulness of NIR-CI and image processing to study and compare the quality of intermediates is demonstrated. In a second part, the simultaneous extraction of spectra and distribution maps without a priori information is proven. The accuracy of NMF, BPSS, MCRALS and PMF algorithms are compared. The latter proves to extract both spectral profile and concentration with the best accuracy especially when rotational tools are used to investigate the space of feasible solutions. The last chapter deals with the quantification of API in binary mixtures and pharmaceutical tablets. The quantification without a priori reveals to be quite challenging. With homogeneous sample, the multivariate curve resolution algorithms fail to recover the pure spectra. A segmentation scheme is appropriate only in specific cases if the chemical species particles are larger than the spatial resolution of the device. If a full range of tablets with known concentration is provided, PLS algorithm gives the most accurate quantification results. However, it is demonstrated that with the only knowledge of reference spectra, PLS-DA provides an estimation of the concentration which allows semi-quantitative analysis of samples when the construction of a full range is not possible for instance during the analysis of development samples