Quantification of 11 C-PIB kinetics in cardiac amyloidosis

Background The purpose of this work was to determine the optimal tracer kinetic model of 11 C-PIB and to validate the use of the simplified methods retention index (RI) and standardized uptake value (SUV) for quantification of cardiac 11 C-PIB uptake in amyloidosis. Methods and results Single-tissue, reversible and irreversible two-tissue models were fitted to data from seven cardiac amyloidosis patients who underwent 11 C-PIB PET scans and arterial blood sampling for measurement of blood radioactivity and metabolites. The irreversible two-tissue model (2Tirr) best described cardiac 11 C-PIB uptake. RI and SUV showed high correlation with the rate of irreversible binding ( K i ) from the 2Tirr model ( r 2 =0.95 and r 2 =0.94). Retrospective data from 10 amyloidosis patients and 5 healthy controls were analyzed using RI, SUV, as well as compartment modelling with a population-average metabolite correction. All measures were higher in amyloidosis patients than in healthy controls ( p =.001), but with an overlap between groups for K i . Conclusion An irreversible two-tissue model best describes the 11 C-PIB uptake in cardiac amyloidosis. RI and SUV correlate well with K i from the 2Tirr model. RI and SUV discriminate better between amyloidosis patients and controls than K i based on population-average metabolite correction.