Now, in the era of hybrid imaging, SPECT/CT devices are used to produce an integrated CT AC image to discriminate between true perfusion defects and artifacts. Acquiring additional prone SPECT images, as well as upright (erect) images, has been described for subdiaphragmatic attenuation to differentiate attenuation artifacts from true hypoperfusion defects, thus improving the quality and increasing the specificity and accuracy of MPI. Several methods have been added to conventional SPECT imaging for attenuation correction (AC). Within the acquired SPECT image, the artifact may appear as a fixed or reversible defect, depending on whether the attenuator is in a constant or variable position in stress and rest image acquisitions ( 2). The severity of the artifact depends on the size and density of the attenuator in relation to adjacent tissue. The location of an attenuation artifact depends on the position of the soft-tissue attenuator in relation to the left ventricle. Patient-related artifacts remain an issue of concern. Researchers are focusing on attenuation artifacts and how to overcome them to improve diagnostic accuracy by reading physicians and certainty about the final report. Patient motion and soft-tissue attenuation are the two most common sources of artifacts in MPI. Many additive techniques have been used to overcome this drawback. These artifacts can be technical or patient-related. ![]() However, imaging artifacts can limit the utility of the study. The increasing use of myocardial perfusion scintigraphy for the diagnosis of clinically important CAD is the direct result of its strengths myocardial perfusion scintigraphy is a robust and highly validated technique, is widely available, and has a clear role in the assessment of patients investigated for CAD, as stated by internationally published guidelines ( 1). Radionuclide myocardial perfusion scintigraphy has become established as one of the main functional cardiac imaging techniques for ischemic heart disease, constituting approximately one third of all nuclear medicine procedures done annually in the United States, with substantial growth annually. Moreover, it has an important role in risk assessment, management decisions, and prognosis for patients with ischemic heart disease. SPECT myocardial perfusion imaging (MPI) is considered a useful noninvasive imaging modality in the evaluation of suspected or established coronary artery disease (CAD). Conclusion: Both CT AC and prone imaging increased the specificity and diagnostic accuracy of MPI without affecting the sensitivity. On the other hand, anterior wall defects were more common in women (83.3%), in whom prone imaging was better than CT AC. Inferior wall defects were more common in men (95%), in whom CT AC performed better than prone imaging (i.e., 92.9% in CT AC vs. Sensitivity, specificity, and diagnostic accuracy were 100%, 90.3%, and 94%, respectively, for CT AC, versus 100%, 83.8%, and 91%, respectively, for prone imaging. Results: It was found that 58% (31/53) of the depicted defects were attributable to attenuation artifacts the CT AC imaging technique was able to correct 52%, versus 49% for prone imaging. Each study was interpreted separately, and their results were compared. All patients underwent ordinary supine stress/rest SPECT MPI followed by additional stress/rest prone SPECT and stress/rest SPECT/CT. Statistical analysis was done for 30 patients with suspected or confirmed ischemic heart disease. Methods: Forty-four patients were initially included in the study. The purpose of this study was to evaluate the role of prone images in attenuation correction (AC) when CT AC is compared with MPI. ![]() Many methods of overcoming attenuation artifacts have been introduced, including prone positioning to avoid breast attenuation or use of hybrid SPECT/CT systems. Breast and subdiaphragmatic artifacts are the most frequent cause of false-positive findings in women. Soft-tissue attenuation of γ-photons is the most common source of artifacts and remains an intricate problem for myocardial perfusion imaging (MPI) by SPECT.
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