Towards comprehensive assessment of mitral regurgitation using cardiovascular magnetic resonance

Abstract

Cardiovascular magnetic resonance (CMR) is increasingly used to assess patients with mitral regurgitation. Its advantages include quantitative determination of ventricular volumes and function and the mitral regurgitant fraction, and in ischemic mitral regurgitation, regional myocardial function and viability. In addition to these, identification of leaflet prolapse or restriction is necessary when valve repair is contemplated. We describe a systematic approach to the evaluation of mitral regurgitation using CMR which we have used in 149 patients with varying etiologies and severity of regurgitation over a 15 month period.Following standard ventricular cine acquisitions, including 2, 3 and 4 chamber long axis views and a short axis stack for biventricular function, we image movements of all parts of the mitral leaflets using a contiguous stack of oblique long axis cines aligned orthogonal to the central part of the line of coaptation. The 8–10 slices in the stack, orientated approximately parallel to a 3-chamber view, are acquired sequentially from the superior (antero-lateral) mitral commissure to the inferior (postero-medial) commissure, visualising each apposing pair of anterior and posterior leaflet scallops in turn (A1-P1, A2-P2 and A3-P3). We use balanced steady state free precession imaging at 1.5 Tesla, slice thickness 5 mm, with no inter-slice gaps. Where the para-commissural coaptation lines curve relative to the central region, two further oblique cines are acquired orthogonal to the line of coaptation adjacent to each commissure. To quantify mitral regurgitation, we use phase contrast velocity mapping to measure aortic outflow, subtracting this from the left ventricular stroke volume to calculate the mitral regurgitant volume which, when divided by the left ventricular stroke volume, gives the mitral regurgitant fraction. In patients with ischemic mitral regurgitation, we further assess regional left ventricular function and, with late gadolinium enhancement, myocardial viability.Comprehensive assessment of mitral regurgitation using CMR is feasible and enables determination of mitral regurgitation severity, associated leaflet prolapse or restriction, ventricular function and viability in a single examination and is now routinely performed at our centre. The mitral valve stack of images is particularly useful and easy to acquire.

Cardiovascular Magnetic Resonance

“…23 Quantification of mitral regurgitation is commonly assessed from the difference in ventricular stroke volumes, but other approaches have been used, including the difference between forward aortic flow and LV stroke volume or mitral inflow volume, and they may be more reliable. 24 CMR has proved useful clinically when the mitral regurgitant jet or jets are highly eccentric, which can preclude adequate assessment by echocardiography.…”

Quantification of Left Ventricular Interstitial Fibrosis in Asymptomatic Chronic Primary Degenerative Mitral Regurgitation

“…14,15 Mitral valve anatomy was assessed using basal short axis and long axis steadystate free-precession cines of the mitral valve after a standardized approach. 16 Mitral regurgitant volume was calculated as the difference between the LV stroke volume and the aortic forward stroke volume. The regurgitant fraction was calculated from the ratio of the mitral regurgitant volume divided by the LV stroke volume (regurgitant fraction (%)=[mitral regurgitant volume÷LV stroke volume]×100).…”

Imaging congenital heart disease in adults

“…Alternatively, regurgitations can be quantified by subtracting the outflow volume, measured by mapping velocities through a plane transecting the relevant great artery, from the corresponding ventricular stroke volume. For identification of tethering, prolapse or failure of coaptation of all parts of the mitral (or tricuspid) leaflets, a contiguous stack of cine images aligned perpendicular to the central part of the line of coaptation is recommended [33,34].…”