False-Positive 99mTc-Pyrophosphate Uptake Due to Myocardial Calcification from Prior Viral Myocarditis.

Abstract

A patient underwent 99mTc-pyrophosphate (PYP) imaging to evaluate for suspected cardiac amyloidosis. Planar imaging demonstrated diffusely increased radiotracer uptake throughout the left ventricular myocardium. On SPECT/CT, these regions of uptake corresponded to extensive myocardial calcifications. Patient had a history of severe myocarditis a year prior with extensive fibrosis documented by cardiac MRI. This case underscores the importance of SPECT/CT correlation in differentiating true cardiac amyloid deposition from false-positive PYP uptake due to dystrophic myocardial calcification.