Added Value of CT Attenuation Correction and Prone Positioning in Improving Breast and Subdiaphragmatic Attenuation in Myocardial Perfusion Imaging

Abstract

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. Breast and subdiaphragmatic artifacts are the most frequent cause of false-positive findings in women. Many methods of overcoming attenuation artifacts have been introduced, including prone positioning to avoid breast attenuation or use of hybrid SPECT/CT systems. The purpose of this study was to evaluate the role of prone images in attenuation correction (AC) when CT AC is compared with MPI. Methods: Forty-four patients were initially included in the study. Statistical analysis was done for 30 patients with suspected or confirmed ischemic heart disease. All patients underwent ordinary supine stress/rest SPECT MPI followed by additional stress/rest prone SPECT and stress/rest SPECT/CT. Each study was interpreted separately, and their results were compared. 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. 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. 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. 90.9% in prone imaging). On the other hand, anterior wall defects were more common in women (83.3%), in whom prone imaging was better than CT AC. Conclusion: Both CT AC and prone imaging increased the specificity and diagnostic accuracy of MPI without affecting the sensitivity.