Work

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

Year: 2026

Type: preprint

Abstract: Background Bone-avid tracer myocardial scintigraphy for the diagnosis of transthyretin amyloid cardiomyopathy (ATTR-CM) has traditionally employed imaging at one or 3-hour intervals. Technetium-99m hydroxymethylene diphosphonate ( 99m Tc-HDP) has unique characteristics that may enable earlier imaging. We investigated the diagnostic concordance of immediate versus 1-hour acquisitions. Methods Consecutive patients with suspected ATTR-CM underwent planar imaging and SPECT/CT immediately and at 1-hour following the administration of 99m Tc-HDP. Perugini grades and heart to contralateral lung (H/CL) ratios were assessed. Target-to-background ratios (TBRs) were calculated on the SPECT/CT acquisitions using the left ventricular (LV) septum and three background regions: aorta, LV blood-pool, and vertebrae. We assessed diagnostic concordance using Cohen’s Kappa ( κ ), temporal stability using paired t -tests, and correlation between timepoints using Pearson’s coefficient ( r ). The 1-hour SPECT/CT interpretation served as the protocol reference standard. Results Forty-eight patients (83% male; median age, 80 [73–85] years) were evaluated. One-hour SPECT/CT identified 19 positive and 29 negative cases. Immediate SPECT/CT demonstrated 100% diagnostic concordance with the 1-hour reference standard ( κ = 1.000; p < 0.001). The LV septum/LV Blood-Pool TBR showed the highest correlation ( r = 0.956; p < 0.001). The LV Septum/Aorta TBR demonstrated high correlation (r = 0.918; p < 0.001) and remained stable in the ATTR-negative cohort (−0.02; p = 0.54). Significant decreases in the LV Septum/Vertebrae TBR were observed in the ATTR-negative (−0.55; p < 0.001) and ATTR-positive cohorts (−1.14; p < 0.001). Conclusions In this cohort of patients with suspected ATTR-CM, immediate 99m Tc-HDP SPECT/CT demonstrated high diagnostic concordance with standard 1-hour acquisitions. This expedited approach may improve nuclear laboratory throughput and patient satisfaction.

Source: medRxiv

DOI: 10.64898/2026.06.16.26355752