1-hour 99m Tc-HMDP cardiac amyloid imaging showed similar diagnostic performance to 3-hour imaging (97% concordance), though CT fusion was needed more frequently at 1 hour (57% vs 31%, P<0.001).
Observational (n=114)
Blinded to imaging timepoint
Does 1-hour 99m Tc-HMDP cardiac amyloid radionuclide imaging provide similar diagnostic performance and interpreter experience compared to 3-hour imaging in patients with suspected transthyretin amyloid cardiomyopathy?
1-hour HMDP cardiac amyloid imaging offers similar diagnostic performance to the guideline-recommended 3-hour protocol, though it more frequently requires CT fusion for anatomic localization due to lower contrast resolution.
Absolute Event Rate: 57% vs 31%
p-value: p=<0.001
BACKGROUND: Guidelines recommend 3-hour cardiac amyloid radionuclide imaging (CARI) for transthyretin amyloid cardiomyopathy. Citing rapid blood clearance of 99m Tc-hydroxymethylene-diphosphonate (HMDP) and efficient laboratory throughput, 1-hour imaging is increasingly practiced despite limited supporting evidence. We sought to compare diagnostic performance and interpreter experience of 1-hour versus 3-hour HMDP-CARI. METHODS: Consecutive patients with suspected transthyretin amyloid cardiomyopathy (n=114) underwent both 1-hour and 3-hour HMDP single photon emission computed tomography (CT)/CT. Two cardiologist-radiologist reader teams, blinded to imaging timepoint (1 versus 3 hours), assessed overall interpretation, single photon emission CT–based Perugini grade, interpretation difficulty, interpreter confidence, and need for CT-fused images for anatomic localization. Discordant, equivocal, and difficult cases were arbitrated by a third tie-breaking team. The myocardial-to-blood-pool radiotracer uptake ratio (3-dimensional Score) was measured as a surrogate of contrast resolution. RESULTS: Interinterpreter agreement was high at both time points (κ≥0.81), with more cases requiring arbitration at 3 hours versus 1 hour (22% versus 13%; P =0.049). Overall interpretation and Perugini grades were concordant between time points in 111/114 (97%) and 106/114 (93%) patients, respectively. Three patients (3%) were negative at 1 hour but equivocal at 3 hours, all of which were clinically ruled out for transthyretin amyloid cardiomyopathy. Interpreter confidence was comparable at both timepoints (97% versus 95%; P =0.317). Compared with 3-hour imaging, contrast resolution was inferior (lower 3-dimensional score, P <0.001) and CT fusion was more frequently needed (57% versus 31%, P <0.001) at 1-hour imaging. CONCLUSIONS: In a prospective, blinded comparison of 1-hour versus 3-hour HMDP-CARI, diagnostic performance and interpreter experience were similar, with readers requesting CT fusion more frequently at 1 hour to optimize myocardial-to-blood pool discrimination.
Tersalvi et al. (Mon,) conducted a observational in Suspected transthyretin amyloid cardiomyopathy (n=114). 1-hour 99m Tc-HMDP cardiac amyloid radionuclide imaging vs. 3-hour 99m Tc-HMDP cardiac amyloid radionuclide imaging was evaluated on Need for CT-fused images for anatomic localization (p=<0.001). 1-hour 99m Tc-HMDP cardiac amyloid imaging showed similar diagnostic performance to 3-hour imaging (97% concordance), though CT fusion was needed more frequently at 1 hour (57% vs 31%, P<0.001).