A New Method for Aortic Valve Planimetry with High-Resolution 3-Dimensional MRI and Its Comparison with Conventional Cine MRI and Echocardiography for Assessing the Severity of Aortic Valvular Stenosis

Figures

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  Fig. 1. Participant flow diagram. EF = ejection fraction, 2D = two-dimensional, 3D = three-dimensional

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  Fig. 2. Cardiovascular magnetic resonance image acquisition scheme for three-dimensional planimetry. Image acquisition duration was 190 ms. Data were acquired at 107–297 ms after the R peak during the systolic phase.

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  Fig. 3. Image prescription of 2D and 3D planimetry sequence. A. Cine images were acquired in three short-axis views covering the aortic valve area, from the left ventricular outflow tract to the ascending aorta at 6-mm intervals, using a segmented steady-state free precession sequence. B. In 3D planimetry, ten contiguous slices were obtained in a single breath hold perpendicular to the long axis of the ascending aorta in the aortic valve plane. The scout view for this acquisition was the mid-systolic phase image of the 3-chamber view cine MRI. The most stenotic portion of the aortic valve was targeted for images in the middle of the slab, corresponding to the mid-systolic phase. 2D = two-dimensional, 3D = three-dimensional

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  Fig. 4. Representative examples of 3D planimetry reconstructed using commercial software (iNtuition, TeraRecon). A. The volume-rendering image shows the 3D structure of the aortic valve. B–D. Two directional cross-sectional images, taken perpendicular to the aortic valve, were used for reconstruction. Note that there is a high-velocity jet (arrow) with high contrast. E. We measured the maximum area of the aortic valve at mid-systole. Avg = average, SDev = standard deviation, 3D = three-dimensional

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  Fig. 5. A representative example of 2D planimetry for cine MRI. A. The steady-state free precession sequence produced a 2D image during multiple phases throughout the cardiac cycle. B. We drew a line along the edge of the maximally open aortic valve on the cine image. 2D = two-dimensional

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  Fig. 6. Assessment of image quality for 2D and 3D planimetry. A–D. Image quality was assessed using a four-point scale as follows. A. 1 = severe blurring of images. B. 2 = moderate blurring of valve contours. C. 3 = mild blurring of valve contours. D. 4 = excellent, with no artifact. Grades 3 and 4 indicated diagnostic quality. 2D = two-dimensional, 3D = three-dimensional

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  Fig. 7. Bland-Altman plot for interobserver agreement for 3D AVA or 2D AVA and TTE. The Bland-Altman plot of the averages of the two measures vs. the differences between the two measures indicated that there was no obvious trend in the 3D planimetry and TTE findings (A), as well as those of 2D planimetry and TTE (B). AVA = aortic valve area, TTE = transthoracic echocardiographic, 2D = two-dimensional, 3D = three-dimensional

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  Fig. 8. A representative case with two separate orifices. The areas for the two orifices were measured twice and summed to calculate the valve area. The 3D planimetry image (A) shows better contrast in the valve orifices than in the 2D image (B). Note the bi-cornuate appearance of the flow jet profile on the volume-rendered image (C). 2D = two-dimensional, 3D = three-dimensional

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  Fig. 9. Comparison of 3D planimetry, 2D planimetry, and CT in a 67-year-old male with calcified bicuspid AV. There was moderate stenosis on transthoracic echocardiography with an AVA of 1.10 cm2 (peak velocity, 3.8 m/s; diameter of LVOT, 2.32 cm; velocity-time integral ratio of LVOT [23.3]/AV [88.0], 0.3). The echocardiographic window was rather poor in this study. Cine MRI shows a stenotic jet through the AV in the 3-chamber view (A). The AVA measured with 3D planimetry was 1.18 cm2 (B). The AVA measured with 2D planimetry was 1.48 cm2 (C). The peripheral and central parts of the AV orifice could not be measured in a single plane on CT (D). Oblique sagittal reformatted image (E) and en-face (F) and profile (G) navigation images of CT show a curved appearance (arrows) of the AV orifice plane. The AVA was 1.29–1.65 cm2 on CT. In this patient, 3D planimetry correlated best with echocardiography for measuring AVA. AV = aortic valve, AVA = aortic valve area, LVOT = left ventricular outflow tract, 2D = two-dimensional, 3D = three-dimensional