The QPS-derived SRS, SSS, and SDS and the proposed [SNR.sub.rest], [SNR.sub.stress], and RSNR were calculated from rest/stress Tl-201 images for all subjects in both study groups.
In the results of the ROC analysis shown in Tables 2 and 3, RSNR performed the best in discriminating subjects with and without TVD, with a sensitivity of 85%, a specificity of 90%, an accuracy of 88%, and an AUC of 0.88.
For RSNR, age, gender, and BMI did not make much differences in the discrimination performances, in general.
Our current data support our working hypothesis concerning the usefulness of RSNR. Using our proposed data processing scheme, the RSNR can be calculated automatically with 85% sensitivity, 90% specificity, and 88% accuracy when used to detect TVD.
We have also evaluated whether age, gender, and BMI would affect the diagnostic performances of RSNR. We found that age does not seem to affect the diagnostic performances with the sensitivity/specificity/accuracy being 81/91/88 (%) in the lower age group and 88/88/88 (%) in the higher age group.
Further, a multicenter trial will be helpful in determining the extent to which the RSNR is dependent on the scanners, protocols, and reconstruction parameters used.
A novel parameter based on the stress-to-rest ratio of the SNR, namely, RSNR, has been proposed and shown to be a potentially useful parameter for detecting TVD with CZT-based SPECT MPI.
The RSNR was 0.91, indicating a low tracer uptake in the stress study and high possibility of present TVD.
The ROC curves for the proposed parameter RSNR and SDS are shown on the same plot.