In-scan and scan-rescan assessment of LV in- and outflow volumes by 4D flow MRI versus 2D planimetry

Abstract

Purpose: To evaluate the in-scan and scan-rescan consistency of left ventricular (LV) in- and outflow assessment from 1) 2D planimetry; 2) 4D flow magnetic resonance imaging (MRI) with retrospective valve tracking, and 3) 4D flow MRI with particle tracing.

Materials and methods: Ten healthy volunteers (age 27 ± 3 years) underwent multislice cine short-axis planimetry and whole-heart 4D flow MRI on a 3T MRI scanner twice with repositioning between the scans. LV in- and outflow was compared from 1) 2D planimetry; 2) 4D flow MRI with retrospective valve tracking over the mitral valve (MV) and aortic valve (AV), and 3) 4D flow MRI with particle tracing through forward and backward integration of velocity data.

Results: In-scan consistency between MV and AV flow volumes is excellent for both 4D flow MRI methods with r ≥ 0.95 (P ≤ 0.001). In-scan AV and MV flow by retrospective valve tracking shows good to excellent correlations versus AV and MV flow by particle tracing (r ≥ 0.81, P ≤ 0.004). Scan-rescan SV assessment by 2D planimetry shows excellent reproducibility (intraclass correlation [ICC] = 0.98, P < 0.001, coefficient of variation [CV] = 7%). Scan-rescan MV and AV flow volume assessment by retrospective valve tracking shows strong reproducibility (ICCs ≥ 0.89, P ≤ 0.05, CVs = 12%), as well as by forward and backward particle tracing (ICCs ≥ 0.90, P ≤ 0.001, CVs ≤ 11%). Multicomponent particle tracing shows good scan-rescan reproducibility (ICCs ≥ 0.81, P ≤ 0.007, CVs ≤ 16%).

Conclusion: LV in- and outflow assessment by 2D planimetry and 4D flow MRI with retrospective valve tracking and particle tracing show good in-scan consistency and strong scan-rescan reproducibility, which indicates that both 4D flow MRI methods are reliable and can be used clinically.

Level of evidence: 2 Technical Efficacy Stage: 2 J. Magn. Reson. Imaging 2018;47:511-522.

Keywords: 2D planimetry; 4D flow MRI; inflow; outflow; stroke volume.

Figure 1

Three methods illustrating the assessment of LV in‐ and outflow volumes. Short‐axis planimetry (in a, planning for multislice 2D short‐axis is illustrated on four‐chamber view and in b, mid‐ventricular short‐axis slice is presented). Streamline representation of 4D flow MRI shows mid‐systolic aortic outflow (c) and early diastolic mitral (d) inflow volume with the positioning of the retrospective valve tracking indicated by a dashed line. (e) Outflow assessment over the aortic valve by forward particle tracing (e) and inflow assessment over the mitral valve by backward particle tracing (f).

Figure 2

Scatterplots and Bland–Altman plots for comparison of left ventricular in‐ and outflow by 2D planimetry and 4D flow MRI with retrospective valve tracking and particle tracing (a) Left: scatterplot depicting the correlation between SV measured by 2D planimetry versus AV flow measured by retrospective valve tracking in scan 1 and scan 2; right: Bland–Altman plot depicting the agreement between SV measured by 2D planimetry versus AV flow measured by retrospective valve tracking in scan 1 and scan 2. (b) Left: scatterplot depicting the correlation between SV measured by 2D planimetry versus AV flow measured by forward particle tracing in scan 1 and scan 2; right: Bland–Altman plot depicting the agreement between SV measured by 2D planimetry versus AV flow measured by forward particle tracing in scan 1 and scan 2. The linear regression lines are plotted in the Bland–Altman plots.

Figure 3

Scatterplots and Bland–Altman plots for comparison of left ventricular in‐ and outflow by 2D planimetry and 4D flow MRI with retrospective valve tracking and 4D flow MRI with backward and forward particle tracing. (a) Left: scatterplot depicting the correlation between SV measured by 2D planimetry in scan 1 and scan 2; right: Bland–Altman plot depicting the agreement between SV measured by 2D planimetry in scan 1 and scan 2. (b) Left: scatterplot depicting the correlation between MV flow measured by retrospective valve tracking with 4D flow MRI in scan 1 and scan 2 and the correlation between AV flow measured by retrospective valve tracking with 4D flow MRI in scan 1 and scan 2; right: Bland–Altman plot depicting the agreement between MV flow measured by retrospective valve tracking with 4D flow MRI in scan 1 and scan 2 and the agreement between AV flow measured by retrospective valve tracking with 4D flow MRI in scan 1 and scan 2. (c) Left: scatterplot depicting the correlation between MV flow measured by 4D flow MRI with backward particle tracing in scan 1 and scan 2 and the correlation between AV flow measured by 4D flow MRI with backward particle tracing in scan 1 and scan 2; right: Bland–Altman plot depicting the agreement between MV flow measured by 4D flow MRI with backward particle tracing in scan 1 and scan 2 and the agreement between AV flow measured by 4D flow MRI with backward particle tracing in scan 1 and scan 2. The linear regression lines are plotted in the Bland–Altman plots.