Attenuation correction of myocardial SPECT by scatter-photopeak window method in normal subjects.

Objective: Segmentation with scatter and photopeak window data using attenuation correction (SSPAC) method can provide a patient-specific non-uniform attenuation coefficient map only by using photopeak and scatter images without X-ray computed tomography (CT). The purpose of this study is to evaluate the performance of attenuation correction (AC) by the SSPAC method on normal myocardial perfusion database.

Methods: A total of 32 sets of exercise-rest myocardial images with Tc-99 m-sestamibi were acquired in both photopeak (140 keV +/- 10%) and scatter (7% of lower side of the photopeak window) energy windows. Myocardial perfusion databases by the SSPAC method and non-AC (NC) were created from 15 female and 17 male subjects with low likelihood of cardiac disease using quantitative perfusion SPECT software. Segmental myocardial counts of a 17-segment model from these databases were compared on the basis of paired t test.

Results: AC average myocardial perfusion count was significantly higher than that in NC in the septal and inferior regions (P < 0.02). On the contrary, AC average count was significantly lower in the anterolateral and apical regions (P < 0.01). Coefficient variation of the AC count in the mid, apical and apex regions was lower than that of NC.

Conclusions: The SSPAC method can improve average myocardial perfusion uptake in the septal and inferior regions and provide uniform distribution of myocardial perfusion. The SSPAC method could be a practical method of attenuation correction without X-ray CT.