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Dissertations / Theses on the topic 'Optoacoustic Imaging'

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Published: 6 September 2023

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1

Tomaszewski, Michal Robert. "Functional imaging of cancer using Optoacoustic Tomography." Thesis, University of Cambridge, 2019. https://www.repository.cam.ac.uk/handle/1810/284931.

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Poor oxygenation of solid tumours has been linked with resistance to chemo- and radio-therapy and poor patient outcomes. Measuring the functional status of the tumour vasculature, including blood flow fluctuations and changes in oxygenation is important in cancer staging and therapy monitoring. A robust method is needed for clinical non-invasive measurement of the oxygen supply and demand in tumours. Current clinically approved imaging modalities suffer high cost, long procedure times and limited spatio-temporal resolution. Optoacoustic tomography (OT) is an emerging clinical imaging modality that can provide static images of endogenous haemoglobin concentration and oxygenation. In this work, an integrated framework for quantitative analysis of functional imaging using OT is developed and applied in vivo with preclinical cancer models. Oxygen Enhanced (OE)-OT is established here to provide insight into tumour vascular function and oxygen availability in the tissue. Tracking oxygenation dynamics using OE-OT reveals significant differences between two prostate cancer models in nude mice with markedly different vascular function (PC3 & LNCaP), which appear identical in static OT. OE-OT metrics are shown to be highly repeatable and correlate directly on a per-tumour basis to tumour vascular maturity, hypoxia and necrosis, assessed ex vivo. Dynamic Contrast Enhanced (DCE) OT demonstrates the relationship between OE-OT response and tumour perfusion in vivo. Finally, the possibility of using OT data acquired at longer wavelengths to report on tumour water and lipid content is investigated, with a view to future providing intrinsically co-registered imaging of tumour oxygenation and cellular necrosis. These findings indicate that OE-OT holds potential for application in prostate cancer patients, to improve delineation of aggressive and indolent disease, while combined with DCE-OT, it may offer significant advantage for localised imaging of tumour response to vascular targeted therapies. Further work is needed to establish whether OT can provide a new method to detect tumour necrosis in vivo.

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2

Gertsch, Andreas Gustav. "Contrast enhancement in optoacoustic imaging using nano particles /." Bern : [s.n.], 2007. http://www.ub.unibe.ch/content/bibliotheken_sammlungen/sondersammlungen/dissen_bestellformular/index_ger.html.

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3

Abeyakoon, Oshaani Vayanthimala. "Clinical translation of optoacoustic imaging in breast cancer." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/276973.

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Optoacoustic (OA) imaging is an emerging low-cost hybrid imaging investigation/technique currently in clinical feasibility studies for breast cancer diagnosis and staging. The technique applies pulsed light to the tissue of interest where molecules absorb the light photons and generate acoustic pressure waves. The resulting acoustic responses are detected using ultrasound transducers and converted into images. Image contrast within a pixel is dependent on the relative concentration and absorption characteristics (i.e. spectrum) of the chromophores within the illuminated tissue. Thus, tissue responses from illumination using multiple wavelengths, chosen to reflect the differential absorption of oxy-/deoxy- and total haemoglobin, can be measured. In turn, these signals can be regarded as surrogate measures of tissue hypoxia and neoangiogenesis, hallmarks of cancer associated with adverse outcomes. The aim of this PhD was to translate optoacoustic imaging into the breast clinic to try and fulfil some of the unmet clinical needs in breast cancer imaging using the imaging biomarker roadmap by O'Connor et al. Translation of this new technology to the clinical environment required extensive preparatory work, including the procurement and installation of a scanner prototype, liaison with UK regulatory bodies to secure ethical and MHRA approval, as well as several technical developments (performed during the course of the PhD) to make the technology suitable for breast cancer imaging. The first chapter of the thesis reviews the unmet needs of breast cancer imaging, being followed by a summary of recent techniques and technologies that may potentially fulfil gaps in knowledge and address some of the specific diagnostic challenges in breast cancer imaging. The capabilities of optoacoustic imaging are then discussed in the context of this evolving landscape of new imaging techniques and technologies with a particular focus on the tumour biology (neoangiogenesis and hypoxia) that can be measured in humans using multimodality and multi parametric imaging. Chapter 2 reviews of the current state of clinical translation of optoacoustic imaging, highlighting the particular areas in which clinical translation has advanced the most (breast cancer, melanoma and inflammatory bowel disease). Chapter 3 discusses the logistical, regulatory and technical challenges and solutions involved in translating optoacoustic imaging to the clinic and setting up a clinical service. Chapter 4 presents a series of validation experiments of oxygen saturation aimed at establishing the relationship between the optoacoustic signal and invasive pO2 measurements with an OxyLite probe in a porcine kidney model. This work was conducted in close collaboration with leading clinicians from the local transplant team. The following chapter describes the results of the first stage of our clinical work in the breast, namely the healthy volunteer study. This part had several aims: to perform qualitative assessment of the optoacoustic features of the normal breast under physiological conditions; to establish a robust scanning technique and identify technical and image interpretation pitfalls; and to perform qualitative evaluation of the hormonal changes that occur during the menstrual cycle and menopause, which, in turn, were used to validate surrogate measures of oxy-, deoxy and total haemoglobin. Chapter 6 then focuses on the qualitative assessment of benign and malignant breast lesions and their appearances on optoacoustic imaging. The patient study was divided into three phases. Phase 1 created a feature set to differentiate benign from malignant lesions, while Phase 2 was a transition between the prototype scanner and the installation of the first-generation clinical scanner. In Phase 3 the feature set created in Phase 1 was validated in a reader study. The sensitivity and specificity of optoacoustic imaging for lesion detection and differentiation of benign from malignant lesions was compared with mammography and ultrasound. Chapter 7 then deals with the quantitative analysis of the Phase 1 and Phase 3 data acquired in Chapter 6, assessing the relationships between the use of single wavelengths, spectral unmixing, vascularity versus receptor status, heterogeneity of signal intensity in relation to tumour stage and grade. This chapter also discusses the potential and limitations of quantifying the optoacoustic signal and leads to the final chapter, a discussion of future directions in optoacoustic imaging in breast cancer. At the end of this thesis, chapter 8 briefly discusses the potential future directions for the use of optoacoustic imaging as a clinical and scientific tool.

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4

Azizian, Kalkhoran Mohammad. "Design and development of a universal handheld probe for optoacoustic-ultrasonic 3D imaging." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSEI027/document.

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La présente dissertation est principalement consacrée à la conception et à la caractérisation d’une sonde universelle pour l’imagerie volumétrique ultrasons-optoacoustique et le développement d’un algorithme de reconstruction adapté aux exigences physiques pour la conception du système. Les traits distinctifs de cette dissertation sont l’introduction d’une nouvelle géométrie pour les sondes manuelles ultrasons-optoacoustique et des évaluations systématiques basées sur des méthodes de pré-reconstruction et post-reconstruction. Pour éviter l’interprétation biaisée, une évaluation capable d’évaluer le potentiel de la sonde doit être faite. Les caractéristiques mentionnées établissent un cadre pour l’évaluation des performances du système d’imagerie d’une manière précise. En outre, elle permet d’optimiser les performances suivant l’objectif fixé. Ainsi, deux algorithmes de reconstruction anticipée ont été élaborés pour la conception du système OPUS (optoacoustique ultrasons) capables de produire des images avec un contraste et une résolution homogènes sur tout le volume d’intérêt. L’intérêt d’avoir de tels algorithmes est principalement dû au fait que l’analyse des données médicales est souvent faite dans des conditions difficiles, car on est face au bruit, au faible contraste, aux projections limités et à des transformations indésirables opérées par les systèmes d’acquisition. Cette thèse montre, aussi, comment les artefacts de reconstruction peuvent être réduits en compensant les propriétés d’ouverture et en atténuant les artefacts dus à l’échantillonnage angulaire parcimonieux. Afin de transférer cette méthodologie à la clinique et de valider les résultats théoriques, une plate-forme d’imagerie expérimentale a été développée. En utilisant le système de mesure développé, l’évolution d’une nouvelle géométrie annulaire parcimonieuse et sa dynamique ont été étudiées et une preuve de concept a été démontrée à travers des mesures expérimentales dans le but d’évaluer les progrès réalisés
When the interest is in multiscale and multipurpose imaging, there exists such a will in integrating multi-modalilties into a synergistic paradigm in order to leverage the diagnostic values of the interrogating agents. Employing multiple wavelengths radiation, optoacoustic imaging benefits from the optical contrast to specifically resolve molecular structure of tissue in a non-invasive manner. Hybridizing optoacoustic and ultrasound imaging comes with the promises of delivering the complementary morphological, functional and metabolic information of the tissue. This dissertation is mainly devoted to the design and characterization of a hybridized universal handheld probe for optoacoustic ultrasound volumetric imaging and developing adaptive reconstruction algorithms toward the physical requirements of the designed system. The distinguishing features of this dissertation are the introduction of a new geometry for optoacoustic ultrasonic handheld probe and systematic assessments based on pre and post reconstruction methods. To avoid the biased interpretation, a de facto performance assessment being capable of evaluating the potentials of the designed probe in an unbiased manner must be practiced. The aforementioned features establish a framework for characterization of the imaging system performance in an accurate manner. Moreover, it allows further task performance optimization as well. Correspondingly, two advanced reconstruction algorithms have been elaborated towards the requirement of the designed optoacoustic-ultrasound (OPUS) imaging system in order to maximize its ability to produce images with homogeneous contrast and resolution over the entire volume of interest. This interest is mainly due to the fact that the medical data analysis pipeline is often carried out in challenging conditions, since one has to deal with noise, low contrast, limited projections and undesirable transformations operated by the acquisition system. The presented thesis shows how reconstruction artifacts can be reduced by compensating for the detecting aperture properties and alleviate artifacts due to sparse angular sampling. In pursuit of transferring this methodology to clinic and validating the theoretical results, a synthetic imaging platform was developed. Using the measurement system, the evolution of a novel sparse annular geometry and its dynamics has been investigated and a proof of concept was demonstrated via experimental measurement with the intention of benchmarking progress

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5

Gao, Du Yang. "Engineering of protein-based multifunctional nanoparticles with near-infrared absorption as photoacoustic contrast agents for biological applications." Thesis, University of Macau, 2018. http://umaclib3.umac.mo/record=b3953810.

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6

Montilla, Leonardo Gabriel. "Advanced Devices for Photoacoustic Imaging to Improve Cancer and Cerebrovascular Medicine." Diss., The University of Arizona, 2013. http://hdl.handle.net/10150/312510.

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Recent clinical studies have demonstrated that photoacoustic imaging (PAI) provides important diagnostic information for breast cancer staging. Despite these promising studies, PAI remains an unfeasible option for clinics due to the cost to implement, the required large modification in user conduct and the inflexibility of the hardware to accommodate other applications for the incremental enhancement in diagnostic information. The research described in this dissertation addresses these issues by designing attachments to clinical ultrasound probes and incorporating custom detectors into commercial ultrasound scanners. The ultimate benefit of these handheld devices is to expand the capability of current ultrasound systems and facilitate the translation of PAI to enhance cancer diagnostics and neurosurgical outcomes. Photoacoustic enabling devices (PEDs) were designed as attachments to two clinical ultrasound probes optimized for breast cancer diagnostics. PAI uses pulsed laser excitation to create transient heating (<1°C) and thermoelastic expansion that is detected as an ultrasonic emission. These ultrasonic emissions are remotely sensed to construct noninvasive images with optical contrast at depths much greater than other optical modalities. The PEDs are feasible in terms of cost, user familiarity and flexibility for various applications. Another possible application for PAI is in assisting neurosurgeons treating aneurysms. Aneurysms are often treated by placing a clip to prevent blood flow into the aneurysm. However, this procedure has risks associated with damaging nearby vessels. One of the developed PEDs demonstrated the feasibility to three-dimensionally image tiny microvasculature (<0.3mm) beyond large blood occlusions (>2.4mm) in a phantom model. The capability to use this during surgery would suggest decreasing the risks associated with these treatments. However, clinical ultrasound arrays are not clinically feasible for microsurgical applications due to their bulky size and linear scanning requirements for 3D. Therefore, capacitive micromachined ultrasound transducer (CMUT) two-dimensional arrays compatible with standard ultrasound scanners were used to generate real-time 3D photoacoustic images. Future probes, designed incorporating CMUT arrays, would be relatively simple to fabricate and a convenient upgrade to existing clinical ultrasound equipment. Eventually, a handheld tool with the ability to visualize, in real-time 3D, the desired microvasculature, would assist surgical procedures. The potential implications of PAI devices compatible with standard ultrasound equipment would be a streamlined cost efficient solution for translating photoacoustics into clinical practice. The practitioner could then explore the benefits of the enhanced contrast adjunctive to current ultrasound applications. Clinical availability of PAI could enhance breast cancer diagnostics and cerebrovascular surgical outcomes.

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7

Oancea, Andreas [Verfasser], Vasilis [Akademischer Betreuer] Ntziachristos, and Franz [Akademischer Betreuer] Pfeiffer. "Optoacoustic System and Method for Mesoscopic Imaging / Andreas Oancea. Gutachter: Franz Pfeiffer ; Vasilis Ntziachristos. Betreuer: Vasilis Ntziachristos." München : Universitätsbibliothek der TU München, 2013. http://d-nb.info/1045730033/34.

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8

Wang, Xueding. "Functional photoacoustic tomography of animal brains." Diss., Texas A&M University, 2004. http://hdl.handle.net/1969.1/2736.

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This research is primarily focused on laser-based non-invasive photoacoustic tomography of small animal brains. Photoacoustic tomography, a novel imaging modality, was applied to visualize the distribution of optical absorptions in small-animal brains through the skin and skull. This technique combines the high-contrast advantage of optical imaging with the high-resolution advantage of ultrasonic imaging. Based on the intrinsic optical contrast, this imaging system successfully visualized three-dimensional tissue structures in intact brains, including lesions and tumors in brain cerebral cortex. Physiological changes and functional activities in brains, including cerebral blood volume and blood oxygenation in addition to anatomical information, were also satisfactorily monitored. This technique successfully imaged the dynamic distributions of exogenous contrast agents in small-animal brains. Photoacoustic angiography in small-animal brains yielding high contrast and high spatial resolution was implemented noninvasively using intravenously injected absorbing dyes. In the appendix, the theory of Monte Carlo simulation of polarized light propagation in scattering media was briefly summarized.

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9

Araque, Caballero Miguel Ángel [Verfasser], Vasilis [Akademischer Betreuer] Ntziachristos, and Rudolf [Akademischer Betreuer] Gross. "Incorporating Sensor Properties in Optoacoustic Imaging / Miguel Angel Araque Caballero. Gutachter: Rudolf Gross ; Vasilis Ntziachristos. Betreuer: Vasilis Ntziachristos." München : Universitätsbibliothek der TU München, 2013. http://d-nb.info/104767873X/34.

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10

Dima, Alexander [Verfasser], Vasilis [Akademischer Betreuer] Ntziachristos, and Klaus [Akademischer Betreuer] Diepold. "Optoacoustic handheld imaging for clinical screening and intervention / Alexander Dima. Betreuer: Vasilis Ntziachristos. Gutachter: Klaus Diepold ; Vasilis Ntziachristos." München : Universitätsbibliothek der TU München, 2016. http://d-nb.info/1093788240/34.

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Araque, Caballero Miguel Ángel Verfasser], Vasilis [Akademischer Betreuer] Ntziachristos, and Rudolf [Akademischer Betreuer] [Gross. "Incorporating Sensor Properties in Optoacoustic Imaging / Miguel Angel Araque Caballero. Gutachter: Rudolf Gross ; Vasilis Ntziachristos. Betreuer: Vasilis Ntziachristos." München : Universitätsbibliothek der TU München, 2013. http://nbn-resolving.de/urn:nbn:de:bvb:91-diss-20131030-1129557-0-2.

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12

Shnaiderman, Rami [Verfasser], Vasilis [Akademischer Betreuer] Ntziachristos, Vasilis [Gutachter] Ntziachristos, and Bernhard [Gutachter] Wolfrum. "Silicon photonics sensors of ultrasound for optoacoustic imaging / Rami Shnaiderman ; Gutachter: Vasilis Ntziachristos, Bernhard Wolfrum ; Betreuer: Vasilis Ntziachristos." München : Universitätsbibliothek der TU München, 2021. http://d-nb.info/1238374034/34.

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13

Taruttis, Adrian [Verfasser], Vasilis [Akademischer Betreuer] Ntziachristos, and Gil G. [Akademischer Betreuer] Westermeyer. "Multispectral optoacoustic tomography for imaging of disease biomarkers / Adrian Taruttis. Gutachter: Gil G. Westermeyer ; Vasilis Ntziachristos. Betreuer: Vasilis Ntziachristos." München : Universitätsbibliothek der TU München, 2012. http://d-nb.info/1037198425/34.

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14

Wißmeyer, Georg [Verfasser], Vasilis [Akademischer Betreuer] Ntziachristos, Vasilis [Gutachter] Ntziachristos, Axel [Gutachter] Haase, and Christian [Gutachter] Jirauschek. "All-optical Ultrasound Detection for Optoacoustic Imaging / Georg Wißmeyer ; Gutachter: Vasilis Ntziachristos, Axel Haase, Christian Jirauschek ; Betreuer: Vasilis Ntziachristos." München : Universitätsbibliothek der TU München, 2019. http://d-nb.info/1205462961/34.

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15

Talbert, Robert John. "Photoacoustic discrimination of viable and thermally coagulated blood for burn injury imaging." Diss., Columbia, Mo. : University of Missouri-Columbia, 2007. http://hdl.handle.net/10355/5081.

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Thesis (M.S.)--University of Missouri-Columbia, 2007.
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 January 11, 2008) Includes bibliographical references.

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Rebling, Johannes Jörg [Verfasser], Daniel [Akademischer Betreuer] Razansky, Daniel [Gutachter] Razansky, and Bjoern [Gutachter] Menze. "Rapid Optoacoustic Imaging for Neurology, Cardiology and Vascular Biology / Johannes Jörg Rebling ; Gutachter: Daniel Razansky, Bjoern Menze ; Betreuer: Daniel Razansky." München : Universitätsbibliothek der TU München, 2019. http://d-nb.info/1202922031/34.

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Liu, Nian [Verfasser], Michael [Akademischer Betreuer] Sattler, Vasilis [Gutachter] Ntziachristos, and Michael [Gutachter] Sattler. "Croconaine-based nanoparticles for efficient optoacoustic imaging and tumor theranostics / Nian Liu ; Gutachter: Vasilis Ntziachristos, Michael Sattler ; Betreuer: Michael Sattler." München : Universitätsbibliothek der TU München, 2021. http://d-nb.info/1235664740/34.

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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.

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Chekkoury-Idrissi, Andrei-Chakib Verfasser], Vasilis [Akademischer Betreuer] [Gutachter] Ntziachristos, and Bjoern Holger [Gutachter] [Menze. "3D mesoscopic scale optoacoustic imaging using linear array transducers / Andrei-Chakib Chekkoury-Idrissi ; Gutachter: Vasilis Ntziachristos, Bjoern Menze ; Betreuer: Vasilis Ntziachristos." München : Universitätsbibliothek der TU München, 2017. http://d-nb.info/112722526X/34.

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Lin, Shengtao, Anant Shah, Javier Hernández-Gil, Antonio Stanziola, Bethany I. Harriss, Terry O. Matsunaga, Nicholas Long, Jeffrey Bamber, and Meng-Xing Tang. "Optically and acoustically triggerable sub-micron phase-change contrast agents for enhanced photoacoustic and ultrasound imaging." ELSEVIER GMBH, URBAN & FISCHER VERLAG, 2017. http://hdl.handle.net/10150/626294.

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We demonstrate a versatile phase-change sub-micron contrast agent providing three modes of contrast enhancement: 1) photoacoustic imaging contrast, 2) ultrasound contrast with optical activation, and 3) ultrasound contrast with acoustic activation. This agent, which we name 'Cy-droplet', has the following novel features. It comprises a highly volatile perfluorocarbon for easy versatile activation, and a near-infrared optically absorbing dye chosen to absorb light at a wavelength with good tissue penetration. It is manufactured via a 'microbubble condensation' method. The phase-transition of Cy-droplets can be optically triggered by pulsed-laser illumination, inducing photoacoustic signal and forming stable gas bubbles that are visible with echo-ultrasound in situ. Alternatively, Cy-droplets can be converted to microbubble contrast agents upon acoustic activation with clinical ultrasound. Potentially all modes offer extravascular contrast enhancement because of the sub-micron initial size. Such versatility of acoustic and optical 'triggerability' can potentially improve multi-modality imaging, molecularly targeted imaging and controlled drug release. (C) 2017 The Authors. Published by Elsevier GmbH.

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Tzoumas, Stratis [Verfasser], Vasilis [Akademischer Betreuer] [Gutachter] Ntziachristos, Fabian [Gutachter] Theis, and Ronald [Gutachter] Sroka. "Methods for Spectral Analysis in Optoacoustic Physiological and Molecular Imaging / Stratis Tzoumas ; Gutachter: Fabian Theis, Ronald Sroka, Vasilis Ntziachristos ; Betreuer: Vasilis Ntziachristos." München : Universitätsbibliothek der TU München, 2017. http://d-nb.info/1133261906/34.

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Mandal, Subhamoy [Verfasser], Vasilis [Akademischer Betreuer] Ntziachristos, Jörg [Gutachter] Conradt, and Vasilis [Gutachter] Ntziachristos. "Visual Quality Enhancement in Optoacoustic Tomography : Methods in Multiscale Imaging and Image Processing / Subhamoy Mandal ; Gutachter: Jörg Conradt, Vasilis Ntziachristos ; Betreuer: Vasilis Ntziachristos." München : Universitätsbibliothek der TU München, 2018. http://d-nb.info/1165227282/34.

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Ron, Avihai [Verfasser], Daniel [Akademischer Betreuer] Razansky, Susanne [Gutachter] Kossatz, and Bernd [Gutachter] Reif. "Whole body optoacoustic tomography for high resolution functional and molecular imaging in mice / Avihai Ron ; Gutachter: Susanne Kossatz, Bernd Reif ; Betreuer: Daniel Razansky." München : Universitätsbibliothek der TU München, 2021. http://d-nb.info/1230552758/34.

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Fehm, Thomas [Verfasser], Daniel [Akademischer Betreuer] [Gutachter] Razansky, Andreas [Gutachter] Bausch, and Eberhard [Gutachter] Riedle. "Volumetric Optoacoustic and Ultrasound Tomography for Imaging of Multi-Scale Dynamics / Thomas Fehm ; Gutachter: Andreas Bausch, Daniel Razansky, Eberhard Riedle ; Betreuer: Daniel Razansky." München : Universitätsbibliothek der TU München, 2017. http://d-nb.info/1137010444/34.

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Kneipp, Moritz [Verfasser], Daniel [Akademischer Betreuer] Razansky, Gil [Gutachter] Westmeyer, Vasilis [Gutachter] Ntziachristos, and Arthur [Gutachter] Konnerth. "Rapid Functional Optoacoustic Imaging of Brain Activity in Murine and Zebrafish Models / Moritz Kneipp ; Gutachter: Gil Westmeyer, Vasilis Ntziachristos, Arthur Konnerth ; Betreuer: Daniel Razansky." München : Universitätsbibliothek der TU München, 2015. http://d-nb.info/1140835076/34.

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Turner, Jake Berry [Verfasser], Vasilis [Akademischer Betreuer] [Gutachter] Ntziachristos, and Erwin [Gutachter] Biebl. "Development of Real-Time Hybrid Focus Optoacoustic Microscopy for Multi-scale Imaging in Scattering Tissues / Jake Berry Turner ; Gutachter: Erwin Biebl, Vasilis Ntziachristos ; Betreuer: Vasilis Ntziachristos." München : Universitätsbibliothek der TU München, 2017. http://d-nb.info/1144483425/34.

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Lin, Hsiao Chun Amy [Verfasser], Daniel [Akademischer Betreuer] [Gutachter] Razansky, and Fabian [Gutachter] Theis. "Scalable imaging of scattering organisms with hybrid selective plane illumination microscopy and optoacoustic tomography / Hsiao Chun Amy Lin ; Gutachter: Fabian Theis, Daniel Razansky ; Betreuer: Daniel Razansky." München : Universitätsbibliothek der TU München, 2017. http://d-nb.info/1139119192/34.

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Lutzweiler, Christian [Verfasser], Vasilis [Akademischer Betreuer] [Gutachter] Ntziachristos, Hans-Joachim [Gutachter] Bungartz, and Oliver [Gutachter] Hayden. "Towards Real-Time Clinical Imaging with Multi-Spectral Optoacoustic Tomography: Reconstruction Approaches and Initial Experimental Studies / Christian Lutzweiler ; Gutachter: Hans-Joachim Bungartz, Vasilis Ntziachristos, Oliver Hayden ; Betreuer: Vasilis Ntziachristos." München : Universitätsbibliothek der TU München, 2017. http://d-nb.info/1140165836/34.

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Soliman, Dominik Maximilian [Verfasser], Vasilis [Akademischer Betreuer] Ntziachristos, Gil G. [Gutachter] Westmeyer, and Sibylle [Gutachter] Ziegler. "Augmented microscopy: Development and application of high-resolution optoacoustic and multimodal imaging techniques for label-free biological observation / Dominik Maximilian Soliman ; Gutachter: Gil G. Westmeyer, Sibylle Ziegler ; Betreuer: Vasilis Ntziachristos." München : Universitätsbibliothek der TU München, 2017. http://d-nb.info/1154931358/34.

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30

Xu, Minghua. "Photoacoustic computed tomography in biological tissues: algorithms and breast imaging." Texas A&M University, 2004. http://hdl.handle.net/1969.1/1275.

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Photoacoustic computed tomography (PAT) has great potential for application in the biomedical field. It best combines the high contrast of electromagnetic absorption and the high resolution of ultrasonic waves in biological tissues. In Chapter II, we present time-domain reconstruction algorithms for PAT. First, a formal reconstruction formula for arbitrary measurement geometry is presented. Then, we derive a universal and exact back-projection formula for three commonly used measurement geometries, including spherical, planar and cylindrical surfaces. We also find this back-projection formula can be extended to arbitrary measurement surfaces under certain conditions. A method to implement the back-projection algorithm is also given. Finally, numerical simulations are performed to demonstrate the performance of the back-projection formula. In Chapter III, we present a theoretical analysis of the spatial resolution of PAT for the first time. The three common geometries as well as other general cases are investigated. The point-spread functions (PSF's) related to the bandwidth and the sensing aperture of the detector are derived. Both the full-width-at-half-maximum of the PSF and the Rayleigh criterion are used to define the spatial resolution. In Chapter IV, we first present a theoretical analysis of spatial sampling in the PA measurement for three common geometries. Then, based on the sampling theorem, we propose an optimal sampling strategy for the PA measurement. Optimal spatial sampling periods for different geometries are derived. The aliasing effects on the PAT images are also discussed. Finally, we conduct numerical simulations to test the proposed optimal sampling strategy and also to demonstrate how the aliasing related to spatially discrete sampling affects the PAT image. In Chapter V, we first describe a prototype of the RF-induced PAT imaging system that we have built. Then, we present experiments of phantom samples as well as a preliminary study of breast imaging for cancer detection.

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31

Sethuraman, Shriram. "Combined intravascular ultrasound and photoacoustic imaging." Thesis, 2007. http://hdl.handle.net/2152/3300.

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The primary focus of the work was to evaluate the capability of intravascular photoacoustic (IVPA) imaging in combination with intravascular ultrasound (IVUS) to detect and differentiate atherosclerotic plaques. The composition rather than structural narrowing of the arteries is a major indicator of the propensity of a vascular lesion to rupture. Consequently, intravascular imaging of these high-risk plaques is required to exactly determine the vulnerable plaque constituents for appropriate follow-up therapy. Our multi-modality imaging approach aims to utilize the high resolution structural assessment abilities of IVUS and the optical contrast of IVPA imaging and is capable of differentiating the lipid, fibrous and fibro-cellular components of an inflammatory lesion. To test the hypothesis, we developed an IVUS catheter based laboratory prototype of a combined IVUS/IVPA imaging system. The performance of the synergistic combination of IVUS and IVPA imaging was evaluated through tissue mimicking phantom studies. Further, to test the ability of the combined imaging to detect plaques, excised samples of an aorta were utilized from a specifically designed animal model of atherosclerosis. Ex-vivo IVPA imaging studies were performed using a 532 nm laser excitation to detect the lipids in the plaque. In addition, multi-wavelength spectroscopic IVPA imaging studies were evaluated to differentiate plaques. Finally, an ultrasound based temperature estimation method was utilized to demonstrate and confirm safety of IVPA imaging for clinical intravascular applications. Upon analysis of the results of our investigation, we believe that IVPA imaging offer numerous potential advantages when integrated with clinical IVUS imaging. The IVUS imaging system with integrated IVPA imaging capability could play a major role in interventional cardiology.
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Park, Suhyun 1977. "Integrated system for ultrasonic, elasticity and photoacoustic imaging." 2008. http://hdl.handle.net/2152/17894.

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By integrating three complementary imaging techniques - ultrasound, elasticity and photoacoustic imaging, a hybrid imaging system utilizing an array transducer is proposed for various biomedical imaging applications including cancer detection, diagnosis and therapy monitoring. Simultaneous imaging of the anatomy (ultrasound imaging), changes in biomechanical properties (elasticity imaging) and cancer-induced angiogenesis (photoacoustic imaging) of tissue is based on many synergistic features of these modalities and may result in a unique and important imaging tool. In this study, numerical analysis and experimental studies are presented to demonstrate the feasibility, to evaluate the performance, and also to improve the quality of the combined array-based ultrasound, elasticity and photoacoustic imaging system. To estimate spatial resolution, a point source was imaged using ultrasound and photoacoustic imaging modes. Then, several tissue mimicking phantoms were examined using ultrasound, photoacoustic and elasticity imaging. In elasticity imaging, ultrasound frames were acquired during deformation of the tissue. To reduce the data acquisition time of the system, high frame rate imaging was used. High frame rate imaging is possible by transmitting a broader and less focused ultrasound beam but the image quality is sacrificed. Thus, we compared the quality of the high frame rate and conventional ultrasound images. In photoacoustic imaging, acoustic transients are generated simultaneously in the entire volume of the laser irradiated tissue. Hence, image formation (beamforming) algorithms were developed based on the characteristics of the photoacoustic signals. Then, adaptive beamforming method is suggested to improve the image quality of the photoacoustic imaging. The results of the numerical analyses and experimental studies clearly indicate that ultrasound, elasticity and photoacoustic imaging techniques complement each other and together provide critical information needed for the reliable detection and diagnosis of diseases.
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(6560621), Brittani Lynn Bungart. "DEVICE AND IMAGE ANALYSIS ADVANCEMENTS TOWARDS PHOTOACOUSTIC AND ULTRASOUND TOMOGRAPHY-GUIDED PROSTATE BIOPSY." Thesis, 2019.

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To confirm the presence of prostate cancer which is the most incident visceral cancer in men, prostate biopsies are acquired using the magnetic resonance imaging fusion-guided prostate biopsy protocol. For this approach annotated magnetic resonance imaging is overlaid onto real-time ultrasound imaging to guide sampling of suspicious regions marked by uroradiologists. Additional biopsy samples are acquired via the previous clinical gold standard, i.e. the templated 12-core transrectal ultrasound-guided prostate biopsy protocol. While this approach improves the sensitivity of the prostate biopsy, a real-time, multiparametric imaging method of identifying biopsy targets could help overcome some of the inherent pitfalls of the magnetic resonance imaging fusion-guided prostate biopsy. Since ultrasound is used during the prostate biopsy, photoacoustic tomography, e.g. a hybrid imaging modality in which clinical ultrasound probes can be used to detect centimeters deep chemical alterations, has the potential to provide real-time targeting during biopsy. The translation of photoacoustic tomography to the clinic for prostate biopsy has been prevented by engineering challenges, which include identification of a biomarker for detecting suspicious regions of tissue and light delivery to the prostate for photoacoustic signal generation. Here, we present a vascular texture analysis method that identified 100% of primary and 67% of secondary tumors in the testing data set of ex vivo human prostate specimens. This method can be applied to future in vivo photoacoustic and ultrasound tomography of human prostates after further optimization of light delivery for photoacoustic tomography. To progress towards achieving this aim, we developed a transurethral light delivery device with angular light coupling method. By controlling the launch angle of the light into the fiber, the conversion of forward to side propagating energy can be improved from 27% to 98%, and the longitudinal emission profile can be controlled in order to illuminate the whole prostate simultaneously.

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Lashkari, Bahman. "Photoacoustic Imaging Using Chirp Technique: Comparison with Pulsed Laser Photoacoustics." Thesis, 2011. http://hdl.handle.net/1807/31825.

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The application of photoacoustic (PA) phenomena to medical imaging has been investigated for more than a decade. To implement this modality, one may choose between two types of laser sources, pulsed or continuous wave (CW). This selection affects all features of the imaging technique. Nowadays pulsed lasers are the state-of-the-art technique in the PA research. In this work, various features of the alternative frequency-domain (FD) PA were investigated. An axially symmetric transfer function model of PA wave generation and a Krimholtz-Leedom-Matthaei (KLM) transducer model were developed and used to analyze the experimental results. The controllable parameters of the FD-PA were optimized to improve the signal-to-noise ratio (SNR), contrast, axial resolution and depth detectivity. For example, it was shown that employing the optimal chirp bandwidth can enhance the SNR by more than 10 dB. In addition to the image produced by the cross-correlation amplitude, the phase of the correlation signal was used as a separate channel. A statistical method was introduced to generate an image from this phase channel, and also to filter the PA amplitude channel. A study was also performed to compare FD PA and the prevalent pulsed method. Various features of both methods were examined experimentally using a dual-mode PA system and under the condition of maximum permissible exposure (MPE). The SNRs of both methods were evaluated theoretically and experimentally. It was shown that at low frequencies, both modalities generate comparable SNRs, and at high frequencies pulsed PA produces superior SNRs and depth detetivity. However, by increasing the laser power and decreasing the chirp duration within the safety limits, the SNR and depth detectivity of the FD-PA method are enhanced considerably. The main cause to achieve lower experimental SNRs than theoretical predictions for pulsed PA response was shown to be the oscillating baseline, which can be partially eliminated by filtering.

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