Validation of 2D flow MRI for helical and vortical flows

Mehmood, Zia, Assadi, Hosamadin ORCID:, Grafton-Clarke, Ciaran ORCID:, Li, Rui, Matthews, Gareth ORCID:, Alabed, Samer, Girling, Rebekah, Underwood, Victoria, Kasmai, Bahman, Zhao, Xiaodan, Ricci, Fabrizio, Zhong, Liang, Aung, Nay, Petersen, Steffen Erhard, Swift, Andrew J., Vassiliou, Vassilios S. ORCID:, Cavalcante, João, van der Geest, Rob J. and Garg, Pankaj ORCID: (2024) Validation of 2D flow MRI for helical and vortical flows. Open Heart, 11 (1). ISSN 2398-595X

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Purpose The main objective of this study was to develop two-dimensional (2D) phase contrast (PC) methods to quantify the helicity and vorticity of blood flow in the aortic root. Methods This proof-of-concept study used four-dimensional (4D) flow cardiovascular MR (4D flow CMR) data of five healthy controls, five patients with heart failure with preserved ejection fraction and five patients with aortic stenosis (AS). A PC through-plane generated by 4D flow data was treated as a 2D PC plane and compared with the original 4D flow. Visual assessment of flow vectors was used to assess helicity and vorticity. We quantified flow displacement (FD), systolic flow reversal ratio (sFRR) and rotational angle (RA) using 2D PC. Results For visual vortex flow presence near the inner curvature of the ascending aortic root on 4D flow CMR, sFRR demonstrated an area under the curve (AUC) of 0.955, p<0.001. A threshold of >8% for sFRR had a sensitivity of 82% and specificity of 100% for visual vortex presence. In addition, the average late systolic FD, a marker of flow eccentricity, also demonstrated an AUC of 0.909, p<0.001 for visual vortex flow. Manual systolic rotational flow angle change (ΔsRA) demonstrated excellent association with semiautomated ΔsRA (r=0.99, 95% CI 0.9907 to 0.999, p<0.001). In reproducibility testing, average systolic FD (FDsavg) showed a minimal bias at 1.28% with a high intraclass correlation coefficient (ICC=0.92). Similarly, sFRR had a minimal bias of 1.14% with an ICC of 0.96. ΔsRA demonstrated an acceptable bias of 5.72°-and an ICC of 0.99. Conclusion 2D PC flow imaging can possibly quantify blood flow helicity (ΔRA) and vorticity (FRR). These imaging biomarkers of flow helicity and vorticity demonstrate high reproducibility for clinical adoption.

Item Type: Article
Additional Information: Funding Information: PG and AJS are funded by Wellcome Trust Clinical Research Career Development Fellowships (220703/Z/20/Z and 205188/Z/16/Z). For the purpose of Open Access, the authors have applied a CG-C BY public copyright licence to any Author Accepted Manuscript version arising from this submission.
Uncontrolled Keywords: cardiology and cardiovascular medicine ,/dk/atira/pure/subjectarea/asjc/2700/2705
Faculty \ School: Faculty of Medicine and Health Sciences > Norwich Medical School
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Depositing User: LivePure Connector
Date Deposited: 27 Mar 2024 10:30
Last Modified: 27 Mar 2024 10:30
DOI: 10.1136/openhrt-2023-002451


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