When echocardiography is uncertain, CMR measures the regurgitant volume and fraction directly by phase-contrast flow and volumetric difference, and the ventricular volumes that decide surgery timing.
Orient first
- Aortic regurgitation: phase-contrast through-plane flow at the sinotubular junction gives forward and backward flow.
- Mitral regurgitation: regurgitant volume = LV stroke volume − aortic forward flow.
- Severity thresholds differ from echocardiography (verify CMR-specific cut-offs).
Acquire the study
- CMR: short-axis cine stack for volumes; phase-contrast flow perpendicular to the aortic and pulmonary valves; cine through the valve planes.
The manoeuvre
- Short-axis stack: LV and RV end-diastolic and end-systolic volumes and stroke volumes in ml.
- Phase-contrast through-plane at the sinotubular junction: forward and reverse flow; regurgitant fraction in %.
- Mitral: regurgitant volume from the volumetric difference in ml; fraction in %.
- Stenosis: peak velocity by in-plane or through-plane phase contrast with a suitable VENC; planimetry of the valve orifice on cine.
- Aortic root and ascending aorta dimensions in mm.
What confirms it
- Internally consistent volumes and flows (RV and LV stroke volumes reconcile).
What licenses you to exclude it
- Regurgitant fraction below the mild threshold with normal ventricular volumes excludes significant regurgitation.
The classic misread
- Aliasing because the VENC was set too low.