Valvular regurgitation flow jet assessment using in vitro 4D flow MRI: Implication for mitral regurgitation

• Published in: Magnetic resonance in medicine Vol. 87; no. 4; pp. 1923 - 1937
• Main Authors: Lee, Jeesoo, Gupta, Aakash N., Ma, Liliana E., Scott, Michel B., Mason, O’Neil R., Wu, Erik, Thomas, James D., Markl, Michael
• Format: Journal Article
• Language: English
• Published: United States Wiley Subscription Services, Inc 01.04.2022
• Subjects: 4D flow MRI; Blood Flow Velocity; Doppler effect; Entrainment; Flow velocity; Heart Valve Diseases; Humans; In vivo methods and tests; Jet flow; jet flow volume; jet momentum; Magnetic Resonance Imaging; Mimicry; mitral regurgitation; Mitral Valve Insufficiency - diagnostic imaging; Momentum; Orifices; peak velocity; Pulsatile Flow; Quantitation; regurgitant volume; Regurgitation; Spatial discrimination; Spatial resolution; Three dimensional printing; Ultrasonic imaging; Ultrasonography; Ultrasound; Velocity; 4D flow MRI; peak velocity; jet momentum; mitral regurgitation; jet flow volume; regurgitant volume
• ISSN: 0740-3194; 1522-2594; 1522-2594
• DOI: 10.1002/mrm.29082

Purpose The purpose of this study was to evaluate the accuracy of four‐dimensional (4D) flow MRI for direct assessment of peak velocity, flow volume, and momentum of a mitral regurgitation (MR) flow jets using an in vitro pulsatile jet flow phantom. We systematically investigated the impact of spatial resolution and quantification location along the jet on flow quantities with Doppler ultrasound as a reference for peak velocity. Methods Four‐dimensional flow MRI data of a pulsatile jet through a circular, elliptical, and 3D‐printed patient‐specific MR orifice model was acquired with varying spatial resolution (1.5–5 mm isotropic voxel). Flow rate and momentum of the jet were quantified at various axial distances (x = 0–50 mm) and integrated over time to calculate Voljet and MTIjet. In vivo assessment of Voljet and MTIjet was performed on 3 MR patients. Results Peak velocities were comparable to Doppler ultrasound (3% error, 1.5 mm voxel), but underestimated with decreasing spatial resolution (−40% error, 5 mm voxel). Voljet was similar to regurgitant volume (RVol) within 5 mm, and then increased linearly with the axial distance (19%/cm) because of flow entrainment. MTIjet remained steady throughout the jet (2%/cm) as theoretically predicted. Four and 9 voxels across the jet were required to measure flow volume and momentum‐time‐integral within 10% error, respectively. Conclusion Four‐dimensional flow MRI detected accurate peak velocity, flow rate, and momentum for in vitro MR‐mimicking flow jets. Spatial resolution significantly impacted flow quantitation, which otherwise followed predictions of flow entrainment and momentum conservation. This study provides important preliminary information for accurate in vivo MR assessment using 4D flow MRI.