Reproducibility of myocardial extracellular volume quantification using dual-energy computed tomography in patients with cardiac amyloidosis.

Background: Quantifying myocardial extracellular volume (ECV) using computed tomography (CT) has been shown to be useful in the evaluation of cardiac amyloidosis. However, the reproducibility of CT measurements for myocardial ECV, is not well-established in patients with proven cardiac amyloidosis.

Methods: This prospective single-center study enrolled cardiac amyloidosis patients to undergo dual-energy CT for myocardial fibrosis assessment. Delayed imaging at 7 and 8 ​min post-contrast and independent evaluations by two blinded cardiologists were performed for ECV quantification using 16-segment (ECV_global) and septal sampling (ECV_septal). Inter- and intraobserver variability and test-retest reliability were measured using Spearman's rank correlation, Bland-Altman analysis, and intraclass correlation coefficients (ICC).

Results: Among the 24 participants (median age ​= ​78, 67 ​% male), CT ECV_global and ECV_septal showed median values of 53.6 ​% and 49.1 ​% at 7 ​min, and 53.3 ​% and 50.1 ​% at 8 ​min, respectively. Inter- and intraobserver variability and test-retest reliability for CT ECV_global (ICC ​= ​0.798, 0.912, and 0.894, respectively) and ECV_septal (ICC ​= ​0.791, 0.898, and 0.852, respectively) indicated good reproducibility, with no evidence of systemic bias between observers or scans.

Conclusions: Dual-energy CT-derived ECV measurements demonstrated good reproducibility in patients with proven cardiac amyloidosis, suggesting potential utility as a repeatable imaging biomarker for this disease.