18F-florbetapir is a promising tracer in amyloidosis. This study evaluates its use in patients with systemic AL amyloidosis (AL) before and after treatment as well as its serial utility in monitoring. Fifteen AL patients with cardiac involvement underwent 18F-florbetapir PET imaging and three patients underwent repeat imaging after chemotherapy. All patients had demonstrable cardiac uptake with 18F-florbetapir. Cardiac uptake appeared greater in chemotherapy-naïve vs. chemotherapy-established AL patients median (left ventricular retention index 0.21 vs. 0.14 min-1, respectively) and greater in patients that had not achieved at least a partial haematological response (left ventricular retention index 0.2 vs. 0.14 min-1, respectively). There was no interval difference in cardiac uptake and no correlation in cardiac uptake with cardiac biomarkers or serum free light chains. This is the largest study of 18F-florbetapir in patients with AL amyloidosis. It is the first study to include patients prior to starting chemotherapy and uniquely includes patients who underwent repeat imaging after chemotherapy. All patients had cardiac uptake with 18F-florbetapir, regardless of haematological or NT-proBNP response to chemotherapy. There was a suggestion that treatment-naïve patients may have higher cardiac uptake. Larger studies are required to establish the role of this tracer in screening patients with amyloidosis for cardiac involvement, discriminating between ATTR and AL amyloidosis, and in disease monitoring.
Keywords: AL; Amyloidosis; PET; florbetapir; imaging.