Amyloid PET imaging in cardiac amyloidosis: a pilot study using ¹⁸F-flutemetamol positron emission tomography

Cardiac amyloidosis is a rare disease characterized by amyloid heart deposits and is usually a part of systemic amyloidosis, in relation to systemic light chain (AL) and transthyretin (ATTR wild-type or genetic) amyloidosis. Several recent studies suggest a promising role of amyloid PET imaging to image cardiac amyloidosis, and several PET tracers are now available for in vivo detection of amyloid deposits. The aim of this study was to evaluate ¹⁸F-flutemetamol in diagnosing cardiac amyloidosis.

We performed a pilot study using ¹⁸F-flutemetamol (Vizamyl™) in 12 patients, 3 control subjects without cardiac amyloidosis, and 9 subjects with documented cardiac amyloidosis. Mean standardized uptake value (SUV) in the left ventricular myocardium and blood pool was determined and semi-quantitative parameter as target to background ratio (TBR, myocardial/blood pool mean SUV ratio) between 10th and 30th minutes was calculated.

Uptake of ¹⁸F-flutemetamol in the left ventricular myocardium was noted in all patients with cardiac amyloidosis except one and none in control patient. The TBR was significantly higher in amyloidosis patients than in control subjects: 1.46, interquartile range (IQR) 1.32-2.06 versus 1.06, IQR 0.72-1.1 (p = 0.033). Only one patient in our study had light chain amyloidosis and showed higher TBR than patients with transthyretin amyloid: TBR 3.0 versus TBR median 1.44, IQR 1.33-1.69.

Amyloid PET tracers such as ¹⁸F-flutemetamol could be a promising tool in diagnosing and in therapy response assessment for patients with cardiac amyloidosis.