Advances in PET-Based Cardiac Amyloid Radiotracers

Abstract

The gold standard for diagnosis of cardiac amyloidosis (CA) is endomyocardial biopsy showing Congo red staining followed by mass spectroscopy, but the diagnosis can also be made with high certainty by demonstration of typical cardiac imaging features along with amyloid on biopsy of another involved organ. The use of cardiac imaging techniques to detect amyloid deposits may frequently obviate the need for invasive methods in order to ascertain the presence, and potentially the type, of amyloid deposition. PURPOSE OF REVIEW: We aim to review the evidence behind the development of novel positron emission tomography (PET) radiotracers for demonstrating cardiac amyloid deposition and potentially distinguishing between light-chain (AL) or transthyretin (ATTR) cardiac amyloidosis. RECENT FINDINGS: Multiple recent studies have shown that thioflavin-analogue tracers such as¹⁸F-florbetapir, ¹⁸F-florbetaben, ¹⁸F-flutemetamol, and ¹¹C-labeled Pittsburg Compound-B (PiB) may be able to fulfill the unmet need of elucidating the presence of amyloid deposition in the heart. Because they bind to the beta-pleated motif of the amyloid fibril due to their similarity to the thioflavin structure, they could potentially be used to image CA (Table 1). The use of PET amyloid radiotracers shows promise; however, further data is needed to define their overall accuracy and additive value to the care of patients with suspected systemic and/or cardiac amyloidosis.

Keywords: Amyloid; Bone scintigraphy; Positron emission tomography; Radiotracers; Transthyretin.