Diagnostic Concordance of Immediate Versus 1-Hour Technetium-99m Hydroxydiphosphonate Scintigraphy in Suspected Transthyretin Amyloid Cardiomyopathy

The study examined the diagnostic accuracy of immediate and 1-hour scintigraphy with Technetium-99m hydroxydiphosphonate (99mTc-HDP) in patients suspected of transthyretin amyloid cardiomyopathy (ATTR-CM). Forty-eight patients (83% male, median age 80 years) underwent imaging immediately and 1 hour after tracer administration. Immediate imaging demonstrated 100% diagnostic concordance with the 1-hour standard protocol (kappa = 1.000). The target-to-background ratio in the left ventricular septum and left ventricular blood pool showed the highest correlation (r = 0.956). The results indicate that immediate-phase imaging with 99mTc-HDP is diagnostically equivalent to the standard 1-hour protocol. This expedited approach may improve nuclear laboratory throughput and patient satisfaction.