Hybrid Imaging (SPECT/CT and PET/CT)—Improving the Diagnostic Accuracy of Functional/Metabolic and Anatomic Imaging
Section snippets
Hybrid Imaging Improving Scintigraphic Image Quality Using CT-Maps for Attenuation Correction
A primary cause for poor image quality of SPECT images is attenuation, which reduces the number of photons received by the gamma camera from the organ of interest. SPECT/CT facilitates attenuation correction using an x-ray–based patient-specific attenuation map that can be obtained rapidly and with higher accuracy than maps generated with external radionuclide sources.1, 2 Other benefits of using CT for attenuation correction include less noise, no influence of the SPECT on CT data, and no need
Hybrid Imaging for Accurate Localization of Scintigraphic Lesions and Separation Between Physiologic and Pathologic Uptake
The ability to identify disease sites based on the functional alteration induced by the disease process regardless of morphologic changes is a major advantage of nuclear medicine. The limited anatomical landmarks of scintigraphic data are, however, a drawback. Sites of increased uptake may represent disease but may also be normal physiologic findings. When scintigraphic lesion appears to represent a true disease site, it is of great importance to accurately localize it and provide the clinician
Hybrid Imaging Detecting More Lesions, Differentiating Benign From Malignant Sites, and Reaching Diagnosis by Combined Functional-Anatomical Characterization
Investigating the clinical performance of FDG-PET/CT in evaluation of cancer, Bar-Shalom et al have shown that combined PET/CT imaging led to retrospective detection of malignant lesions previously missed on diagnostic stand-alone CT or on the independent reading of the PET and CT components of the PET/CT study.89 In this study, 63 of 586 sites (11%) were detected on diagnostic CT and on the CT component of PET/CT, only after being identified on the fused images.89 In a study by Israel et al
Hybrid Imaging for Better Delineation of Tumor Boundaries: Optimizing Biopsy, Surgery, and Radiotherapy
Physicians interpreting PET/CT studies are familiar with the heterogenic tracer uptake in different locations within tumor masses and the possible discrepancy in tumor boundaries between CT and PET. Accurate definition of the boundaries of active disease may be of clinical relevance in guiding biopsy site and in planning surgery and radiotherapy fields.
Sampling error can be caused by the presence of necrotic areas within the tumor mass or because of the heterogeneity in tumor aggressiveness in
Hybrid Imaging for Assessment of Disease Activity in the Presence Residual Morphologic Abnormalities After Therapy
Assessment of disease activity after therapy is a major task of functional imaging in variable oncologic and nononcologic clinical scenarios as no infrequent structural abnormalities may remain after an eventually successful therapy. The degree of confidence in detecting or excluding active disease can be improved by fused imaging, which specifically determines the location of tracer within residual abnormalities detected on CT. This is beneficial if normal anatomy is distorted or when the
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