18Fluorine sodium fluoride positron emission tomography, a potential biomarker of transthyretin cardiac amyloidosis.

Background: Non-invasive imaging to diagnose and quantify amyloid load, progression, and response to treatment are central for the care of patients with cardiac amyloidosis. 18Fluorine-labeled sodium fluoride (18F-NaF) is a widely available radioisotope and PET imaging allows for absolute quantification of tracer uptake.

Methods: Patients with biopsy-proven transthyretin (ATTR-CA) and light-chain cardiac amyloidosis (AL) (3 ATTRwt, 2 ATTRV122I, 2 AL) and controls (n = 5), underwent 18F-NaF PET imaging. Scans were assessed visually for radiotracer uptake and analyzed using standard uptake values in the entire myocardium (SUVm) and in a 17-segment cardiac model. Wilcoxon rank-sum tests were used for statistical analyses.

Results: Qualitative 18F-NaF uptake was absent in controls and AL patients. There was qualitative 18F-NaF uptake in ATTR-CA patients, with slightly increased uptake in wild-type patients. SUVm for controls and AL patients overlapped at 0.8(0.4-0.9) and 0.95(0.9-1.0), respectively (P = 0.434). At 1.5(1.4-1.7), SUVm for ATTR-CA patients was ≈1.5*SUVm of controls (P = 0.012) and AL patients (P = 0.078). While there was diffuse 18F-NaF myocardial in ATTR-CA patients, the degree of uptake varied according to cardiac segment.

Conclusion: 18F-NaF PET effectively imaged and differentiated ATTR-CA patients. Semi-automatic software enabled quantification of radiotracer uptake and regional distribution. 18F-NaF PET may be useful for disease monitoring and localizing amyloid deposition in ATTR-CA patients.