Journal Article

A novel approach to determine aortic valve area with phase-contrast cardiovascular magnetic resonance

Reinstadler, Sebastian J., Lechner, Ivan, Troger, Felix, Pamminger, Mathias, Holzknecht, Magdalena, Klug, Gert, Bauer, Axel, Kremser, Christian, Reindl, Martin, Tiller, Christina, Metzler, Bernhard, Mayr, Agnes, Schwaiger, Johannes

2022

Overview

Background Transthoracic echocardiography (TTE) is the diagnostic routine standard for assessing aortic stenosis (AS). However, its inaccuracies in determining stroke volume (SV) and aortic valve area (AVA) call for a more precise and dependable method. Phase-contrast cardiovascular magnetic resonance imaging (PC-CMR) is a promising tool to push these boundaries. Thus, the aim of this study was to validate a novel approach based on PC-CMR against the gold-standard of invasive determination of AVA in AS compared to TTE. Methods A total of 50 patients with moderate or severe AS underwent TTE, cardiac catheterization and CMR. AVA via PC-CMR was determined by plotting momentary flow across the valve against flow-velocity. SV by CMR was measured directly via PC-CMR and volumetrically using cine-images. Invasive SV and AVA were determined via Fick-principle and Gorlin-formula, respectively. TTE yielded SV and AVA using continuity equation. Gradients were calculated via the modified Bernoulli-equation. Results SV by PC-CMR (85 ± 31 ml) correlated strongly (r: 0.73, p < 0.001) with cine-CMR (85 ± 19 ml) without significant bias (lower and upper limits of agreement (LLoA and ULoA): − 41 ml and 44 ml, p = 0.83). In PC-CMR, mean pressure gradient correlated significantly with invasive determination (r: 0.36, p = 0.011). Mean AVA, as determined by PC-CMR during systole (0.78 ± 0.25 cm 2 ), correlated moderately (r: 0.54, p < 0.001) with invasive AVA (0.70 ± 0.23 cm 2 ), resulting in a small bias of 0.08 cm 2 (LLoA and ULoA: − 0.36 cm 2 and 0.55 cm 2 , p = 0.017). Inter-methodically, AVA by TTE (0.81 ± 0.23 cm 2 ) compared to invasive determination showed similar correlations (r: 0.58, p < 0.001 with a bias of 0.11 cm 2 , LLoA and ULoA: − 0.30 and 0.52, p < 0.001) to PC-CMR. Intra- and interobserver reproducibility were excellent for AVA (intraclass-correlation-coefficients of 0.939 and 0.827, respectively). Conclusions Our novel approach using continuous determination of flow-volumes and velocities with PC-CMR enables simple AVA measurement with no bias to invasive assessment. This approach highlights non-invasive AS grading through CMR, especially when TTE findings are inconclusive.

• Publisher: BioMed Central,BioMed Central Ltd,Elsevier
• Subject: Angiology / Aorta / Aortic stenosis / Aortic valve / Aortic Valve - diagnostic imaging / Aortic valve stenosis / Aortic Valve Stenosis - diagnostic imaging / Bias / Cardiac catheterization / Cardiac magnetic resonance imaging / Cardiology / Cardiovascular disease / Catheterization / Catheters / Comparative analysis / Continuity equation / Correlation / Echocardiography / Flow velocity / Heart rate / Heart valves / Humans / Imaging / Intubation / Magnetic Resonance Imaging / Magnetic Resonance Spectroscopy / Mathematical analysis / Medicine / Medicine & Public Health / Methods / Normal distribution / Phase-contrast-CMR / Predictive Value of Tests / Radiology / Reproducibility of Results / Stroke volume / Systole / Valvular heart disease / Velocity