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Browsing by Subject "SPECT"
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Item Beta Cell Imaging—From Pre-Clinical Validation to First in Man Testing(MDPI, 2020-10-01) Demine, Stephane; Schulte, Michael L.; Territo, Paul R.; Eizirik, Decio L.; Radiology and Imaging Sciences, School of MedicineThere are presently no reliable ways to quantify human pancreatic beta cell mass (BCM) in vivo, which prevents an accurate understanding of the progressive beta cell loss in diabetes or following islet transplantation. Furthermore, the lack of beta cell imaging hampers the evaluation of the impact of new drugs aiming to prevent beta cell loss or to restore BCM in diabetes. We presently discuss the potential value of BCM determination as a cornerstone for individualized therapies in diabetes, describe the presently available probes for human BCM evaluation, and discuss our approach for the discovery of novel beta cell biomarkers, based on the determination of specific splice variants present in human beta cells. This has already led to the identification of DPP6 and FXYD2γa as two promising targets for human BCM imaging, and is followed by a discussion of potential safety issues, the role for radiochemistry in the improvement of BCM imaging, and concludes with an overview of the different steps from pre-clinical validation to a first-in-man trial for novel tracers.Item Imaging of Myocardial Fatty Acid Oxidation(Elsevier, 2016-10) Mather, Kieren J; DeGrado, Tim; Medicine, School of MedicineMyocardial fuel selection is a key feature of the health and function of the heart, with clear links between myocardial function and fuel selection and important impacts of fuel selection on ischemia tolerance. Radiopharmaceuticals provide uniquely valuable tools for in vivo, non-invasive assessment of these aspects of cardiac function and metabolism. Here we review the landscape of imaging probes developed to provide noninvasive assessment of myocardial fatty acid oxidation (MFAO). Also, we review the state of current knowledge that myocardial fatty acid imaging has helped establish of static and dynamic fuel selection that characterizes cardiac and cardiometabolic disease and the interplay between fuel selection and various aspects of cardiac function.Item PET and SPECT Imaging of Brain Neoplasia Mimics(Elsevier, 2020-12) Gray, Benjamin R.; Agarwal, Atul; Tann, Mark; Koontz, Nicholas A.; Radiology and Imaging Sciences, School of MedicineSeveral non-neoplastic processes, including infection, inflammation, demyelination, vasculitis, autoimmune disease, and post-treatment changes (radiation therapy or chemoradiation) can result in a mass-like, space-occupying lesion on conventional computed tomography (CT) or magnetic resonance (MR) imaging of the brain. Additionally, non-neoplastic processes can produce imaging findings that mimic nontumoral neoplastic involvement of the central nervous system. Such instances pose a substantial diagnostic dilemma for interpreting radiologists, as well as clinicians tasked with determining the appropriate diagnostic tests and therapeutic strategies for these patients. Nuclear medicine studies, including single positron emission computed tomography (SPECT) and positron emission tomography (PET), as well as hybrid SPECT/CT, PET/CT, and PET/MRI may offer important diagnostic insights into these challenging cases, often helping to differentiate these mimics from true brain neoplasms. In this review, we detail common and uncommon brain tumor mimics in specific context of PET and SPECT imaging of the brain, including the multimodality imaging appearance of tumor mimics and the potential roles these modalities may play in providing diagnostic clarity.Item PET and SPECT Imaging of the Brain: History, Technical Considerations, Applications, and Radiotracers(Elsevier, 2020-12) Davis, Korbin M.; Ryan, Joshua L.; Aaron, Vasantha D.; Sims, Justin B.; Graduate Medical Education, School of MedicineAdvances in nuclear medicine have revolutionized our ability to accurately diagnose patients with a wide array of neurologic pathologies and provide appropriate therapy. The development of new radiopharmaceuticals has made possible the identification of regional differences in brain tissue composition and metabolism. In addition, the evolution of 3-dimensional molecular imaging followed by fusion with computed tomography and magnetic resonance imaging have allowed for more precise localization of pathologies. This review will introduce single photon emission computed tomography and positron emission tomographic imaging of the brain, including the history of their development, technical considerations, and a brief overview of pertinent radiopharmaceuticals and their applications.Item Post Yttrium-90 Imaging(Thieme, 2021) Rice, Mitchell; Krosin, Matthew; Haste, Paul; Radiology and Imaging Sciences, School of MedicineTransarterial radioembolization with yttrium-90 ( 90 Y) is a mainstay for the treatment of liver cancer. Imaging the distribution following delivery is a concept that dates back to the 1960s. As β particles are created during 90 Y decay, bremsstrahlung radiation is created as the particles interact with tissues, allowing for imaging with a gamma camera. Inherent qualities of bremsstrahlung radiation make its imaging difficult. SPECT and SPECT/CT can be used but suffer from limitations related to low signal-to-noise bremsstrahlung radiation. However, with optimized imaging protocols, clinically adequate images can still be obtained. A finite but detectable number of positrons are also emitted during 90 Y decay, and many studies have demonstrated the ability of commercial PET/CT and PET/MR scanners to image these positrons to understand 90 Y distribution and help quantify dose. PET imaging has been proven to be superior to SPECT for quantitative imaging, and therefore will play an important role going forward as we try and better understand dose/response and dose/toxicity relationships to optimize personalized dosimetry. The availability of PET imaging will likely remain the biggest barrier to its use in routine post- 90 Y imaging; thus, SPECT/CT imaging with optimized protocols should be sufficient for most posttherapy subjective imaging.Item Quantitative evaluation of the effect of attenuation correction in SPECT images with CT-derived attenuation(SPIE, 2019) Tavakoli, Meysam; Naji, Maryam; Physics, School of ScienceIn this study, we assessed the importance of attenuation correction by quantitative evaluation of errors associated with attenuation in myocardial SPECT in a phantom study. To do attenuation correction we use an attenuation map derived from X-ray CT data. The succession of attenuation correction highly depends on high quality of attenuation maps. CT derived attenuation map in related to non-uniform attenuation correction is used to do transmission dependent scatter correction. The OSEM algorithm with attenuation model was developed and used for attenuation correction during image reconstruction. Finally a comparison was done between reconstructed images using our OSEM code and analytical FBP method. The results of measurements show that: Our programs are capable to reconstruct SPECT images and correct the attenuation effects. Moreover to evaluate reconstructed image quality before and after attenuation correction we applied a famous approach using Image Quality Index. Attenuation correction increases the quality and quantity factors in both methods. This increasing is independent of activity in quantity factor and decrease with activity in quality factor. Both quantitative and qualitative of SPECT images were improved by attenuation correction. In both OSEM and FBP the activity ratio of heart phantom in comparison with the markers was very increased. So the attenuation correction in fat patients and low activity is recommended. Attenuation correction with CT images and OSEM reconstruction in the condition of complete registration yields superior results.