Kinetic analysis of cardiac dynamic ¹⁸F-Florbetapir PET in healthy volunteers and amyloidosis patients: A pilot study

Objectives: This study aimed to explore the potential of full dynamic PET kinetic analysis in assessing amyloid binding and perfusion in the cardiac region using F-18-Florbetapir PET, establishing a quantitative approach in the clinical assessment of cardiac amyloidosis disease. Materials & methods: The distribution volume ratios (DVRs) and the relative transport rate constant (R-1), were estimated by a pseudo-simplified reference tissue model (pSRTM2) and pseudo-Logan plot (pLogan plot) with kidney reference for the region of interest-based and voxel-wise-based analyses. The parametric images generated using the pSRTM2 and linear regression with spatially constrained (LRSC) algorithm were then evaluated. Semi-quantitative analyses include standardized uptake value ratios at the early phase (SUVREP, 0.5-5 min) and late phase (SUVRLP, 50-60 min) were also calculated. Results: Ten participants [7 healthy controls (HC) and 3 cardiac amyloidosis (CA) subjects] underwent a 60-min dynamic F-18-Florbetapir PET scan. The DVRs estimated from pSRTM2 and Logan plot were significantly increased (HC vs CA; DVRpSRTM2: 0.95 +/- 0.11 vs 2.77 +/- 0.42, t'(2.13) = 7.39, P = 0.015; DVRLogan: 0.80 +/- 0.12 vs 2.90 +/- 0.55, t'(2.08) = 6.56, P = 0.020), and R-1 were remarkably decreased in CA groups, as compared to HCs (HC vs CA; 1.08 +/- 0.37 vs 0.56 +/- 0.10, t'(7.63) = 3.38, P = 0.010). The SUVREP and SUVRLP were highly correlated to R-1 (r = 0.97, P < 0.001) and DVR(r = 0.99, P < 0.001), respectively. The DVRs in the total myocardium region increased slightly as the size of FWHM increased and became stable at a Gaussian filter >= 6 mm. The secular equilibrium of SUVR was reached at around 50-min p.i. time. Conclusion: The DVR and R-1 estimated from cardiac dynamic F-18-Florbetapir PET using pSRTM with kidney pseudo-reference tissue are suggested to quantify cardiac amyloid deposition and relative perfusion, respectively, in amyloidosis patients and healthy controls. We recommend a dual-phase scan: 0.5-5 min and 50-60 min p.i. as the appropriate time window for clinically assessing cardiac amyloidosis and perfusion measurements using F-18-Florbetapir PET.