Yield of a novel ultra-low-dose computed tomography device mounted on a dedicated cardiac SPECT system in improving the accuracy of myocardial perfusion imaging and the detection of chest abnormalities

Background. To examine the yield of an ultra-low-dose computed tomography (CT) transmission module for attenuation-correction (AC) on a dedicated cardiac camera in evaluation of SPECT-myocardial perfusion imaging (MPI) in the diagnosis of CAD and for additional chest abnormalities. Methods. The study group included 150 patients with known or suspected CAD referred for technetium sestamibi SPECT MPI. CT transmission scanning (effective radiation 0.17 mSv) was performed after each gated SPECT scan. AC and non-corrected (NC) SPECT scans were evaluated on a 5-point scale using a 17-segment model, and the sum stress score (SSS) and sum rest score (SRS) were calculated for each condition. Overall image quality, sensitivity and normalcy rate (51 patients) and processing of 28 CT slices were screened for chest findings. Results. CT-based AC significantly improved image quality (P = .01). Mean SSS was 3.8 ± 5.8 with AC and 6.1 ± 7.1 with NC (P < .001); the respective SRS values were 2.6 ± 6.3 and 3.9 ± 7.7 (P < .001). The sensitivity of detecting ≥70% stenosis was 71% and 86% (P = NS) and the normalcy rate was 30% and 89% (P < .0001) in NC and AC SPECT MPI, respectively. Chest CT: Lung abnormalities in 31%, aortic calcifications in 27%, and hiatus hernia in 5%. Conclusions. Ultra-low-dose CT for AC of SPECT-MPI improves image quality, diagnostic accuracy and suggests detection of chest findings.