Circulation derived from 4D flow MRI correlates with right ventricular dysfunction in patients with tetralogy of Fallot

Figures

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  Figure 1. Study design and enrollment flow chart. TOF Tetralogy of Fallot, CMR cardiac magnetic resonance, bSSFP balanced steady-state free precession, RV right ventricular, EF ejection fraction, EDVi end-diastolic volume indexed for body surface area, ESVi end-systolic volume indexed for body surface area, PRF pulmonary regurgitant fraction, MPA main pulmonary artery.

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  Figure 2. A 14-year-old boy with repaired Tetralogy of Fallot. Streamline imaging by 4D flow magnetic resonance imaging visualizes the pulmonary arteries. Clockwise vortices are seen at the posterior portion of the proximal main pulmonary artery when viewed from the patient’s left (arrow). Flow visualization was performed using 4D flow postprocessor software (iT Flow; Cardioflow Design. Inc., Tokyo, Japan). MPA main pulmonary artery, LPA left pulmonary artery, RPA right pulmonary artery.

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  Figure 3. Time-circulation curve of the cross section of the proximal main pulmonary artery (white line in the right upper figure). The maximum and minimum values were obtained from the time- circulation curve. The integral value (area under the time-circulation curve = yellow area) was obtained by integration of the circulation values throughout a single cardiac cycle.

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  Figure 4. Streamline imaging flows of the pulmonary arteries of a 40-year-old man with repaired TOF (Case 6). The leftmost image and middle image show short-axis vorticities; the rightmost image shows a long-axis vorticity. The white lines in the uppermost row, where the vorticity was calculated, correspond to the cross sections shown in the middle row. The location of the measurement in the proximal MPA occurred at 1 cm above the pulmonic valve (a: white line). The location of the measurement in the distal MPA occurred at 1 cm below the bifurcation of the MPA into the right and left pulmonary arteries (b: white line). The longitudinal circulation was measured parallel to the clockwise systolic vortex in the MPA (c: white line). Vortex formation in the 3 different cross sections of the main pulmonary artery demonstrates the clockwise vortices in red and the counterclockwise vortices in blue [d: cross sections of the proximal MPA, e: cross section of the distal MPA, f: cross section of the vortex (middle row)]. The area surrounded by the yellow dotted line was the region where circulation (area integral of vorticity) was calculated (d: short-axis proximal MPA, e: short-axis distal MPA, f:…

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  Figure 5. Streamline imaging flows of the pulmonary arteries of 20 patients with repaired Tetralogy of Fallot. Case 1–5 did not show a vortex in the main pulmonary arteries (MPA), however, there were vortical or helical flows in the right and left PA in some patients. Case 6–20 showed vortex formation in the MPA. Vortices typically originated posteriorly in the MPA (Type 1: Case 6–13) and formed helices. Other vortices originated from the MPA bifurcation to the right PA (Type 2: Case 16–19), at the proximal right PA (Type 3: Case 14, 15), or from the MPA bifurcation to the left PA (Type 4: Case 20). Arrows indicate vortices and arrowheads indicate the left pulmonary artery stenosis. F female, M male, RVEF right ventricular ejection fraction, PRF pulmonary regurgitant fraction, Circulation longitudinal integral circulation value. Flow visualization was performed using 4D flow postprocessor software (iT Flow; Cardioflow Design. Inc., Tokyo, Japan).

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  Figure 6. Correlations between integral circulation and RV functions. The short-axis integral circulations in the proximal MPA show significant positive correlations with RVESVi and RVEDVi (upper 2 graphs). The longitudinal integral circulation shows a negative correlation with RVEF and a positive correlation with RVESVi (lower 2 graphs).