Purpose: Our aim was to compare MPI scan outcomes and post-scan referral for invasive coronary angiography (ICA) between patients undergoing MPI with cadmium-zinc -telluride (CZT)-SPECT or PET in perfectly comparable groups generated by propensity score matching.
Method: 1188 patients who underwent MPI CZT-SPECT (Discovery 570, GE Healthcare) with attenuation correction and 487 patients who underwent Rb-82 PET (D690, GE Healthcare) were retrospectively analyzed. Propensity score-based matching was performed using calcium score category (0, 1-100, 101-400, >400), gender, age, body weight, current smoker, diabetes mellitus, hypercholesterolemia, hypertension and family history as variables. The frequency of normal scans, post scan ICA, and percutaneous coronary intervention (PCI) or coronary bypass surgery (CABG) within six months, were compared between SPECT and PET patients.
Results: After matching, no significant differences were found between the PET (n=487) and SPECT group (n=487) except for weight (91 vs. 87kg, respectively, p<0.001). PET scans were more often interpreted as normal (84% vs. 74%, p<0.001). The number of scans showing ischemia or possible ischemia was lower for PET (10.8%) than for SPECT (21.2%, p<0.001). The percentage of ICA (9.7 vs. 11.3%, p=0.41), PCI (1.9% vs. 2.5%, p=0.51) or CABG (1.4% vs. 1.6%,p=0.80) did not differ between the PET and SPECT, respectively.
Conclusion: As compared to CZT-SPECT, Rb-82 PET MPI results in more normal scans and fewer diagnoses of ischemia and doubtful ischemia. However, this did not translate to fewer ICA and PCI procedures within 6 months, but this may require more experience among referring cardiologists.