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In vitro Assessment of Aortic Regurgitation Using Four-Dimensional Flow Magnetic Resonance Imaging
Published on: February 25, 2022
Two-Minute k-Space and Time-accelerated Aortic Four-dimensional Flow MRI: Dual-Center Study of Feasibility and Impact
Emilie Bollache1, Kristopher D Knott1, Kelly Jarvis1
1Department of Radiology, Northwestern University, Feinberg School of Medicine, 737 N Michigan Ave, Suite 1600, Chicago, IL 60611 (E.B., K.J., R.S.D., L.C., S.R., J.C.C., J.D.C., A.J.B., M.M.); Sorbonne Université, CNRS, INSERM, Laboratoire d'Imagerie Biomédicale, Paris, France (E.B.); Barts Heart Centre, London, England (K.D.K., R.B., C.C., P.S., T.T., J.C.M., S.E.P.); Institute of Cardiovascular Science, University College London, London, England (K.D.K., P.S., T.T., J.C.M.); Department of Radiology, Academic Medical Center, Amsterdam, the Netherlands (P.v.O.); Department of Diagnostic Imaging, University Children's Hospital, Zurich, Switzerland (J.G.); NIHR Barts Biomedical Research Unit, William Harvey Research Institute, Queen Mary University of London, London, England (S.E.P.); and Department of Biomedical Engineering, Northwestern University, McCormick School of Engineering, Evanston, Ill (M.M.).
Purpose:
To investigate the two-center feasibility of highly k-space and time (k-t)-accelerated 2-minute aortic four-dimensional (4D) flow MRI and to evaluate its performance for the quantification of velocities and wall shear stress (WSS).
Materials And Methods:
This cross-sectional study prospectively included 68 participants (center 1, 11 healthy volunteers [mean age ± standard deviation, 61 years ± 15] and 16 patients with aortic disease [mean age, 60 years ± 10]; center 2, 14 healthy volunteers [mean age, 38 years ± 13] and 27 patients with aortic or cardiac disease [mean age, 78 years ± 18]). Each participant underwent highly accelerated 4D flow MRI (k-t acceleration, acceleration factor of 5) of the thoracic aorta. For comparison, conventional 4D flow MRI (acceleration factor of 2) was acquired in the participants at center 1 (n = 27). Regional aortic peak systolic velocities and three-dimensional WSS were quantified.
Results:
k-t-accelerated scan times (center 1, 2:03 minutes ± 0:29; center 2, 2:06 minutes ± 0:20) were significantly reduced compared with conventional 4D flow MRI (center 1, 12:38 minutes ± 2:25; P < .0001). Overall good agreement was found between the two techniques (absolute differences ≤15%), but proximal aortic WSS was significantly underestimated in patients by using k-t-accelerated 4D flow when compared with conventional 4D flow (P ≤ .03). k-t-accelerated 4D flow MRI was reproducible (intra- and interobserver intraclass correlation coefficient ≥0.98) and identified significantly increased peak velocities and WSS in patients with stenotic (P ≤ .003) or bicuspid (P ≤ .04) aortic valves compared with healthy volunteers. In addition, k-t-accelerated 4D flow MRI-derived velocities and WSS were inversely related to age (r ≥-0.53; P ≤ .03) over all healthy volunteers.
Conclusion:
k-t-accelerated aortic 4D flow MRI providing 2-minute scan times was feasible and reproducible at two centers. Although consistent healthy aging- and disease-related changes in aortic hemodynamics were observed, care should be taken when considering WSS, which can be underestimated in patients.© RSNA, 2019See also the commentary by François in this issue.
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