“Loss of Bone Signal” on 99mTc-Labeled Pyrophosphate Scintigraphy in a Patient With Wild-Type Transthyretin Amyloidosis

Abstract

99mTc-3,3-diphosphono-1,2-propanedicarboxylic acid (DPD) scintigraphy and 99mTc-pyrophosphate (PYP) scintigraphy are highly sensitive modalities for imaging both myocardial and extracardiac amyloid transthyretin in patients with wild-type transthyretin (ATTRwt) amyloidosis. “Loss of bone signal” on planar imaging of 99mTc-DPD scintigraphy, in which the tracer uptake in bone is obscured by marked tracer uptake in the overlying skeletal muscles, is reported. However, this phenomenon has not yet been documented on 99mTc-PYP scintigraphy. We describe an 89-year-old woman with ATTRwt amyloidosis in whom “loss of bone signal” together with marked tracer uptake into the skeletal muscles was clearly demonstrated on 99mTc-PYP scan.