Cardiac amyloidosis is a differential diagnosis in heart failure and is associated with high mortality. There is currently no noninvasive imaging test available for specific diagnosis. N-[methyl-(11)C]2-(4'-methylamino-phenyl)-6-hydroxybenzothiazole ((11)C-PIB) PET is used in the evaluation of brain amyloidosis. We evaluated the potential use of (11)C-PIB PET in systemic amyloidosis affecting the heart.
Methods: Patients (n = 10) diagnosed with systemic amyloidosis-including heart involvement of either monoclonal immunoglobulin light-chain (AL) or transthyretin (ATTR) type-and healthy volunteers (n = 5) were investigated with PET/CT using (11)C-PIB to study cardiac amyloid deposits and with (11)C-acetate to measure myocardial blood flow to study the impact of global and regional perfusion on PIB retention.
Results: Myocardial (11)C-PIB uptake was visually evident in all patients 15-25 min after injection and was not seen in any volunteer. A significant difference in (11)C-PIB retention in the heart between patients and healthy controls was found. The data indicate that myocardial amyloid deposits in patients diagnosed with systemic amyloidosis could be visualized with (11)C-PIB. No correlation between (11)C-PIB retention index and myocardial blood flow as measured with (11)C-acetate was found on the global level, whereas a positive correlation on the segmental level was seen in a single patient.
Conclusion: (11)C-PIB and PET could be a method to study systemic amyloidosis of type AL and ATTR affecting the heart and should be investigated further both as a diagnostic tool and as a noninvasive method for treatment follow-up.