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Images from Radioactivity: Radionuclide Scans, SPECT, and PET
Published in Suzanne Amador Kane, Boris A. Gelman, Introduction to Physics in Modern Medicine, 2020
Suzanne Amador Kane, Boris A. Gelman
These ECT techniques are useful in a variety of diagnostic applications in cardiology. For example, PET can be used to measure the extent to which the blood supply to a region of heart muscle is intact by measuring the source activity of a blood perfusion agent. The absence of the radioactive tracer can be used to map out regions of impaired blood flow. At the same time, the same region's metabolism can be assessed using FDG scans since the heart muscle can utilize glucose as a fuel. If the heart muscle is viable, then it should exhibit high rates of FDG metabolism. This information can be combined to determine, for example, whether a region of tissue is healthy enough to benefit from an interventional procedure to re-establish blood flow. SPECT and PET can be used in cancer imaging to determine the blood supply to a tumor, to probe tumor metabolism, or to measure the distribution of radiopharmaceuticals specifically targeted to tumors. This information can help track the spread of tumors within the body or probe for their recurrence after surgery to remove the cancer.
Biomedical Imaging Molecular Imaging
Published in Lawrence S. Chan, William C. Tang, Engineering-Medicine, 2019
Christian J. Konopka, Emily L. Konopka, Lawrence W. Dobrucki
Active vs. passively targeted. PET and SPECT contrast agents are generally termed radiotracers. These radiotracers can also be targeted or non-targeted contrast agents. The key difference between MI and nuclear medicine is that MI uses radiotracers and contrast agents that are specific for the measurement of a certain biological process, whereas nuclear medicine also uses radiotracers that are non-specific, but still clinically useful. For instance, SPECT tracer 67Ga-citrate is a SPECT radiotracer which can be useful for detecting malignant tumor tissue, but it is not specific for any molecular process; rather, it accumulates in tumor tissue because the 67Ga is treated as a ferrous ion in the body and accumulates in sites of inflammation such as cancer or infection sites. 67Ga-citrate uptake on SPECT or 2-D scintigraphy studies can therefore locate primary tumors, metastases, and infections. In contrast to 67Ga-citrate, 18F-fluoroestradiol (FES) is a MI radiotracer used for imaging breast cancers with PET. FES specifically binds to estrogen receptors and its uptake can predict the treatment effect of salvage hormonal therapy and guide therapeutic regimens for breast cancer patients (Linden et al. 2006).
Nanotechnology in Preventive and Emergency Healthcare
Published in Bhaskar Mazumder, Subhabrata Ray, Paulami Pal, Yashwant Pathak, Nanotechnology, 2019
Nilutpal Sharma Bora, Bhaskar Mazumder, Manash Pratim Pathak, Kumud Joshi, Pronobesh Chattopadhyay
SPECT is a type of diagnostic imaging technique in which tomographs of a radionuclide distribution are generated from gamma photons detected at numerous positions about the distribution. SPECT, as routinely performed in nuclear medicine clinics, uses for photon detection/data acquisition an imaging system composed of one or more rotating gamma cameras. In a process known as image reconstruction, tomographs are computed from the data using software that inverts a mathematical model of the data acquisition process. Nanoparticles present significant benefits over conventional molecular imaging using antibodies. The number of modifications that an antibody can accommodate is far lower compared to that which a nanoparticle of a similar size can carry. This is primarily due to the loss of antibody activity with the increase in the number of modifications; a direct result of conformation changes in the protein structure and the consequent loss in the antigen identification sites (Debbage and Jaschke, 2008; Minchin and Martin, 2010; Patel et al., 2012). SPECT is analogous to PET and provides extensive whole-body and quantitative molecular imaging by employing contrast agents, such as 177Lu, 99mTc, 111In, and 123I. PET and SPECT tracers are also useful beyond the realm of contrast agents and have been utilized for organ and blood vessel characterization, functional imaging, pharmacokinetics, and treatment response (Amen et al., 2008; Brom et al., 2010; Dijkgraaf and Boerman et al., 2010; Ji and Travin, 2010; Valotassiou et al., 2010).
A feature selection using improved dragonfly algorithm with support vector machine for breast cancer prediction
Published in Computer Methods in Biomechanics and Biomedical Engineering: Imaging & Visualization, 2023
S. Roselin Mary, R. Murali Prasad, R. Suguna
Numerous methods for the early detection of breast cancer have been developed in the last few years. When a biopsy is performed, the biopsy sample is taken from the patient’s breast tissue (Das et al. 2022). Although the test yields more precise results, the biopsy technique is both unpleasant and pitiful. As a result, the majority of patients are uninterested in this procedure. With a mammography (Sahu et al. 2023), you can see a 2D projection image of your breast and determine if you have cancer. MRI, PET, CT, and single-photon emission computed tomography (SPECT) are used to identify the breast cancer at its various stages (Akay 2009; Yeh et al. 2009; Jafari et al. 2018). When used in conjunction with mammography, the MRI has the potential to miss some cancers that would otherwise be picked up by the latter test. MRI is used by women who have been diagnosed with breast cancer to determine the true size of the breast and to detect the presence of an additional disease in the organ. It produces stunning 3D graphics and clearly demonstrates the dynamic capabilities of Flash. Contrast-enhanced imaging is used in MRI scans.
Prostate-specific membrane antigen-directed imaging and radioguided surgery with single-photon emission computed tomography: state of the art and future outlook
Published in Expert Review of Medical Devices, 2022
Luca Filippi, Barbara Palumbo, Viviana Frantellizzi, Susanna Nuvoli, Giuseppe De Vincentis, Angela Spanu, Orazio Schillaci
Nuclear medicine is based on the administration of radiopharmaceuticals aimed to investigate physio-pathological phenomena at a cellular and molecular level. After radiotracers’ injection and localization in the site of interest, imaging is obtained through the detection of the photons produced during the process of radioactive decay and the interaction with the neighboring tissues. When single-photon emitting tracers are employed, detection is carried out by gamma-camera through planar images and/or SPECT. The main advantage of planar images is their capability to register in real-time radiotracers’ biodistribution through dynamic acquisition, while the main limitation is the low sensitivity since only photons emitted parallel to the collimators (or within a certain angular region, if collimators different from parallel are employed) are allowed to reach the detectors [19]. SPECT is obtained by rotating detectors around the patient, so that it is possible to acquire the activity distribution under multiple angles, namely ‘projections,’ that are then reconstructed into a 3D volume through several software packages. Hybrid SPECT/CT, combining a variable-angle gamma-camera with an X-ray tube, allows an accurate co-registration of functional and anatomical images and also provides attenuation map of the patient [20].
On convergence analysis of an accelerated EM algorithm for SPECT imaging
Published in Applicable Analysis, 2021
Jinping Wang, Jing Bu, Yao Guo
Single-photon emission computed tomography (SPECT) is based on measurements of gamma rays radiated by trace amounts of a radionuclide injected into a patient. The intensities of the radiation measured by a spatially collimated gamma-camera are related to values of line integrals of the radionuclide distribution, with exponential weights representing the attenuation of radiation on its way from a source to the detector. The sought quantity is the radionuclide distribution; it has to be reconstructed numerically from the measured data. The above-mentioned exponential weights are determined by a position-dependent attenuation coefficient; when SPECT is performed in such regions as a human thorax, this dependence cannot be neglected and has to be accounted for by the reconstruction algorithm. SPECT has been widely used in clinical diagnosis and treatment in modern nuclear medicine; not only can it reconstruct distribution levels and activities of the radiation dose which is the distribution of radiotracer concentration inside the body, but also the device is simple and the imaging cost is low.