Novel contouring method for optimizing MRI flow quantification in patients with aortic valve disease

Figures

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  Fig. 1. Schematic showing antegrade jet going through AoV orifice, surrounded by secondary flow jets

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  Fig. 2. A shows axial slice of AAo at the level of the right pulmonary artery (RPA). B (LV 3 chamber view) and C (LVOT view) show the slice position of phase contrast velocity encoded sequences at the level of the AAo (dashed line) and STJ (dotted line). The AoV short axis stack (rectangle) consisted of a 5–8 slice SSFP cine stack with a plane parallel to the AoV hinge points as seen on 3 chamber and LVOT views

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  Fig. 3. SSC at AoV level demonstrated in patient with bicuspid AoV (A magnitude image, B phase velocity map image), and in another patient with a tricuspid AoV (C magnitude image, D velocity image). Note that the proper choice of aliasing velocity (just above Vmax) creates more visual contrast on the velocity map images that aids in contour placement

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  Fig. 4. SSC contouring at AoV level is demonstrated on magnitude images in a patient with tricuspid AoV, during select representative phases of the cardiac cycle: A (peak systole), B (end-systole), C (end-systole, contour omitted to show how the leaflet borders were visualized for demarcation), and D (mid-diastole, demonstrating how the whole lumen, not selective contouring, was done during diastole)

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  Fig. 5. Bland Altman plots. Points above solid black like indicate patients with forward flow > LV SV, while points below the line indicate patients with forward flow < LV SV. Blue dashed line = mean difference between forward flow and LV SV across patients (i.e. bias of flow measurement). Blue shaded area = 95% CI for bias. Green dashed lines = limits of agreement between forward flow and LV SV. Green shaded areas = 95% CI for limits of agreement

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  Fig. 6. Proportion of cases where the absolute difference between forward flow and LV SV was less than or equal to a given threshold. N = 98 patients for SC at AoV and SSC at AoV, 82 patients for SC at STJ, and 97 patients for SC at aorta

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  Fig. 7. Forward flow derived by SSC versus SC at AoV level. SSC gave an equal or larger value than the SC method for 86 of the 98 patients (88%)

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  Fig. 8. Excerpt from Leonardo Da Vinci’s notebook, showing aortic flow vortices closing the aortic valve from the side (image used with permission of the Royal Collection Trust/ © Her Majesty Queen Elizabeth II 2021)