Imaging of cardiac amyloidosis using dynamic ¹⁸F-FPYBF-2 positron emission tomography

Purpose: This study aimed to evaluate the diagnostic ability of 5-(5-(2-(2-(2-¹⁸F-fluoroethoxy) ethoxy) ethoxy) benzofuran-2-yl)-N-methylpyridin-2-amine (¹⁸F-FPYBF-2) dynamic PET for patients with cardiac amyloidosis (CA).

Methods: The subjects were patients diagnosed with proven amyloidosis (n = 16) including transthyretin cardiac amyloidosis (ATTR-CA) (n = 7) and light chain amyloidosis (AL amyloidosis) (n = 9), of which 4 and 5 with (AL-CA) and without (AL-nCA) cardiac involvement, and 4 control subjects suffering from some symptoms of cardiac failure without amyloidosis (CTL). Thirty minutes dynamic ¹⁸F-FPYBF-2 PET/CT was performed to evaluate the time activity curve and the retention index (mRI) as the ratio of the myocardial SUV at 15 to 5 min. The results of bone scan were also evaluated except for 2 AL-nCA cases.

Results: Diffuse ¹⁸F-FPYBF-2 distribution in the myocardium was observed within a few minutes in all cases. The accumulation was still seen at 30 min after injection in all the CA cases, while it showed rapid clearance in CTL and AL-nCA cases. The values mRI of the ATTR-CA and AL-CA were significantly higher than CTL and AL-nCA cases, and AL-CA showed higher value than ATTR-CA (p < 0.05), while the positive results of bone scan were observed in all ATTR-CA cases, and in one case of AL-CA.

Conclusions: ¹⁸F-FPYBF-2 PET could be a useful tool to evaluate cardiac involvement of amyloidosis and can visualize AL-CA regardless of the results of bone scan.