Cardiac amyloidosis is an important cause of restrictive cardiomyopathy and congestive heart failure. Bone scintigraphy with [Tc]hydroxymethylene diphosphonate (Tc-HDP) and [F]sodium fluoride (F-NaF) have been investigated in the noninvasive diagnosis of transthyretin (ATTR)-related cardiac amyloidosis. We present a case of a 76-year-old man with metastatic prostate cancer who underwent Tc-HDP bone scintigraphy with an incidental finding of diffuse left ventricular abnormal uptake suggesting ATTR cardiac amyloidosis. Review of previous imaging showed a negative F-NaF PET/CT study. This example suggests that the mechanism of uptake of Tc-HDP and F-NaF may differ in patients with ATTR cardiac amyloidosis.