Clinical significance of reverse perfusion pattern in Rubidium-82 myocardial perfusion PET-CT studies

Objectives A reverse redistribution pattern during myocardial perfusion imaging is most widely described in SPECT myocardial perfusion studies using thallium (Tl-201), when stress images demonstrates greater perfusion in comparison to rest portion of the study. Reverse perfusion (RP) pattern may also occur in Rubidium-82 PET-CT myocardial perfusion studies, but its significance hasn’t been studied in the current literature. The purpose of this study is to evaluate clinical significance of RP pattern in Rb-82 PET-CT myocardial perfusion studies.

Methods We retrospectively reviewed 389 consecutive Rb-82 PET-CT myocardial perfusion studies performed in our center over a 14 month period. The studies were evaluated for misregistration, motion and attenuation artifacts. 12 (3%) patients demonstrated RP. Of those with RP, only four patients had undergone cardiac catheterization within 12 months of PET imaging. Correlation was sought between the presence and location of angiographic stenosis and RP pattern.

Results 3/4 (75%) had significant (>60%) coronary stenosis; 2 single-vessel, and one two-vessel disease. Stenosis location correlates with the RP territory; Circumflex/Lateral 1/1, RCA/Inferior 1/1, and only one patient with RP pattern in anterior wall segment had significant stenosis in RCA territory. The RP could not be explained by any imaging artifacts in any of these studies.

Conclusions PET studies show markedly less prevalence of artifactual RP in comparison to reported literature of MIBI and Thallium SPECT studies. The presence of reverse perfusion on Rb-82 PET-CT myocardial perfusion studies may implicate coronary disease and may not be attributed merely to artifact. However, since this is an uncommon finding, larger scale population studies need to be done for better evaluation of reverse perfusion pattern significance on PET Rubidium studies