Comparing slow- versus high-speed CT for attenuation correction of cardiac SPECT perfusion studies.

Background: For SPECT, CT-based attenuation correction is preferred. Many different models of CT are available with SPECT/CT systems. Our study compares clinical cardiac SPECT images that were attenuation corrected using slow-rotation CT and high-speed CT transmission scans.

Methods: We evaluated 59 rest/stress perfusion studies from patients who had undergone both a SPECT/CT with a slow-rotation CT and a perfusion study on a PET/CT camera equipped with a high-speed CT scanner. Each SPECT study was reconstructed with transmission maps from both CT scans and the relative perfusion was assessed using semi-automated software. The summed stress/rest/and difference scores (SSS/SRS/SDS) were compared as well as the test classification.

Results: The intraclass correlation coefficients for the SSS, SRS, and SDS were 0.97, 0.96, and 0.80 respectively. There were no significant differences in the mean SSS, SRS, or SDS with the use of either CT for attenuation corrections. Classifying SSS > 3 as abnormal, there was 97% concordance (κ = 0.88). Classifying SDS > 1 as abnormal, there was 95% concordance (κ = 0.54). A McNemar's test showed no significant differences.

Conclusions: There were no significant differences between using a high-speed CT and using a slow-rotation CT for attenuation correction of SPECT myocardial perfusion images.