Computed tomography angiography (CTA) assessment of myocardial extracellular volume fraction (CT-ECV) is feasible, although the protocols for imaging acquisition and post-processing methodology have varied. We aimed to identify a pragmatic protocol for CT-ECV assessment encompassing both imaging acquisition and post-processing methodologies to facilitate its clinical implementation.
We evaluated consecutive patients with severe aortic stenosis undergoing evaluation for transcatheter aortic valve replacement (TAVR). Pre-contrast and 3-min-delayed CTA were obtained in systole using either helical prospective-ECG-triggered (high-pitch) or axial sequential-ECG-gated acquisition, adding to standard TAVR CTA protocol. Using a dedicated software for co-registration of CTA datasets, three methodologies for ECV measurement were evaluated: (1) mid-septum region of interest (Septal ECV), (2) averaged-global ECV (Global ECV) encompassing 16-AHA segments, and (3) average of septal and lateral segments (Averaged ECVsep and Averaged ECVlat).
Among the 142 patients enrolled (median = 81 years, 44% females), 8 were excluded due to significant imaging artifacts precluding Global ECV assessment. High-pitch scan mode was performed in 68 patients (48%). Suboptimal image quality for Global ECV assessment was associated with high-pitch scan mode (odds ratio: OR = 2.26, p = 0.036), along with the presence of intracardiac leads (OR = 4.91, p = 0.002), and BMI≥35 kg/m2 (OR = 2.80, p = 0.026). Septal ECV [median = 29.4%] and Averaged ECVsep [29.0%] were similar (p = 0.108), while Averaged ECVlat [27.5%] was lower than Averaged ECVsep (p < 0.001), resulting in lower Global ECV [28.6%].
Myocardial CT-ECV assessment is feasible using a systolic sequential acquisition pre-contrast, and similar additional 3-min delayed scan. Septal ECV measurement provides similar values to Global ECV and is equally reproducible.
Abbreviations:AF (atrial fibrillation), AS (aortic stenosis), BMI (body mass index), CTA (computed tomography angiography), ECV (extracellular volume fraction), ECG (electrocardiography), MRI (magnetic resonance imaging)
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Published online: March 13, 2023
Accepted: February 24, 2023
Received in revised form: February 12, 2023
Received: December 29, 2022
Publication stageIn Press Journal Pre-Proof
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