4D Flow Cardiovascular Magnetic Resonance-Derived Flow Biomarkers for Early Detection of Flow Abnormalities: A Multicohort New Zealand Based Study

Abstract

Four-dimensional (4D) flow cardiovascular magnetic resonance (4D flow CMR) imaging has evolved as a versatile imaging technique for the assessment of cardiovascular three-dimensional time resolved haemodynamics. This study aimed to examine the utility and metrics derived from 4D flow CMR in different patient cohorts. Controls (n=26), adult tetralogy of Fallot (rToF; n=14), and left ventricular hypertrophy (LVH; n=10) patients were scanned at the Centre of Advanced MRI, University of Auckland. Quantification of flow and examination of between-group differences were performed. Intraclass correlation coefficients (ICC) were used to correlate 4D and 2D CMR. Forward flow rates averaged in the pulmonary veins were significantly greater in LVH than controls (79.11±54.24 mL/sec vs 32.58±35.98 mL/sec, respectively, p<0.05), as was the pulmonary venous atrial reversal peak velocity (–0.44±0.23 m/sec vs –0.13±0.27 m/sec, respectively, p<0.05). Mitral indices of net flow and peak velocity expressed no significant between-group differences. In the rToF group, quantification of pulmonary artery and branches demonstrated a good correlation with 2D CMR. Greatest correlation was between pulmonary artery backward flow (difference of s–2.50±6.91 mL/cycle, ICC 0.96). In relation to pulmonary valve regurgitation categorisation, 1 of 14 cases were differently categorised using 4D flow (ICC 0.91). Quantification of flow with 4D flow CMR was feasible, with a single acquisition introducing an array of flow metrics that may be valuable for the evaluation of various conditions. Larger scale investigations of 4D flow CMR are required, with wider-scale application in routine clinical workflows.