Importance of imaging-acquisition protocol and post-processing analysis for extracellular volume fraction assessment by computed tomography

• Published in: Journal of cardiovascular computed tomography 2023-05, Vol.17 (3), p.222-225
• Main Authors: Koike, Hideki, Cheng, Victor Y., Lesser, Andrew, Enriquez-Sarano, Maurice, Caye, David J., Aluru, John Sukumar, Stanberry, Larissa I., Schelbert, Erik B., Sato, Hirotomo, Fukui, Miho, Bapat, Vinayak N., Sorajja, Paul, Lesser, John R., Cavalcante, João L.
• Format: Article
• Language: English
• Subjects: And intracardiac device; Aortic stenosis; Aortic Valve Stenosis - diagnostic imaging; Aortic Valve Stenosis - surgery; Computed Tomography Angiography - methods; Female; High-pitch scan acquisition; Humans; Male; Predictive Value of Tests; Prospective Studies; Sequential prospective-gated scan acquisition; Tomography, X-Ray Computed; Transcatheter aortic valve replacement; Transcatheter Aortic Valve Replacement - adverse effects; Transcatheter Aortic Valve Replacement - methods
• ISSN: 1934-5925; 1876-861X
• DOI: 10.1016/j.jcct.2023.02.007

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 ​