The utility of Rb PET for myocardial viability assessment: Comparison with perfusion-metabolism Rb-F-FDG PET.

BACKGROUND

Rb kinetics may distinguish scar from viable but dysfunctional (hibernating) myocardium. We sought to define the relationship between Rb kinetics and myocardial viability compared with conventional Rb and F-fluorodeoxyglucose (FDG) perfusion-metabolism PET imaging.

METHODS

Consecutive patients (N = 120) referred for evaluation of myocardial viability prior to revascularization and normal volunteers (N = 37) were reviewed. Dynamic Rb 3D PET data were acquired at rest. F-FDG 3D PET data were acquired after metabolic preparation using a standardized hyperinsulinemic-euglycemic clamp. Rb kinetic parameters K, k, and partition coefficient (KP) were estimated by compartmental modeling RESULTS: Segmental Rb k and KP differed significantly between scarred and hibernating segments identified by Rb-FDG perfusion-metabolism (k, 0.42 ± 0.25 vs. 0.22 ± 0.09 min; P < .0001; KP, 1.33 ± 0.62 vs. 2.25 ± 0.98 ml/g; P < .0001). As compared to Rb-FDG analysis, segmental Rb KP had a c-index, sensitivity and specificity of 0.809, 76% and 84%, respectively, for distinguishing hibernating and scarred segments. Segmental k performed similarly, but with lower specificity (75%, P < .001) CONCLUSIONS: In this pilot study, Rb kinetic parameters k and KP, which are readily estimated using a compartmental model commonly used for myocardial blood flow, reliably differentiated hibernating myocardium and scar. Further study is necessary to evaluate their clinical utility for predicting benefit after revascularization.