Early-phase myocardial uptake intensity of 99m Tc-HMDP vs 99m Tc-DPD in patients with hereditary transthyretin-related cardiac amyloidosis

This study sought to compare the intensity of early-phase myocardial uptake of two phosphonate-based radiotracers, 99mtc-hydroxymethylene diphosphonate (hmdp) and 99mtc-3,3-diphosphono-1,2-propanodicarboxylic acid (dpd), in patients with hereditary transthyretin-related cardiac amyloidosis (ttr-ca). six patients with biopsy-proven diagnosis of ttr-ca and characteristic amyloid fibril composition underwent early-phase 99mtc-hmdp myocardial scintigraphy as part of their routine workup; they were later assessed by 99mtc-dpd scintigraphy after having signed informed written consent. heart-to-mediastinum-ratio was measured at both time points as well as regional distribution on 17-segment analysis. all patients had an h/m ratio >1.28 on both imaging. 99mtc-dpd uptake was slightly higher than 99mtc-hmdp uptake in 3 patients, but no statistical difference was found (p = 0.13). regional distribution of the two radiotracers was well correlated on bull’s eyes analysis, with only slight underestimation of 99mtc-dpd uptake in the anterior/apical segments, compared with 99mtc-hmdp. 99mtc-hmdp and 99mtc-dpd show comparable myocardial uptake intensity on early-phase scintigraphy and can be used alternatively for the diagnosis of ttr-ca.