Cardiovascular magnetic resonance imaging in mitral valve disease

Abstract

This paper describes the role of cardiovascular magnetic resonance (CMR) imaging in assessing patients with mitral valve disease. Mitral regurgitation (MR) is one of the most prevalent valvular heart diseases. It often progresses without significant symptoms, leading to left ventricular overload, dysfunction, frequent decompensated heart failure episodes, and excess mortality. Cardiovascular magnetic resonance assessment is recommended for MR when routine ultrasound imaging information is insufficient or discordant. A well-planned CMR can provide an in-depth assessment of the mitral valve apparatus, leaflet morphology, and papillary muscles. In addition, it can precisely inform the impact of MR on left atrial and ventricular remodelling. The review aims to highlight established and emerging techniques for morphological assessment, flow assessment (including regurgitation and stenosis), myocardial assessment, and haemodynamic assessment of mitral valve disease by CMR. It also proposes a simplified clinical flow chart for CMR assessment of the mitral valve.

Keywords: Chordae tendineae; Haemodynamics; Heart failure; Heart valve diseases; Humans; Magnetic resonance imaging; Mitral valve; Mitral valve insufficiency; Papillary muscles.

Graphical Abstract

Role of cardiovascular magnetic resonance in mitral regurgitation (MR) assessment, focusing on left ventricular/left atrial (LV/LA) volumes, MR quantification, aetiology, and myocardial tissue. Key implications include predicting LV remodelling, timing of MV intervention, identifying heart failure sub-phenotypes, assessing arrhythmogenicity, and mortality risk.

Figure 1

(A) Recommended CMR protocol for mitral valve assessment by CMR. (B) How to plan the long-axis cine acquisitions of the mitral valve using the enface short-axis mitral valve image. Contiguous modified three-chamber cines intersecting the commissural line are planned to localize segmental pathologies such as billowing, prolapse, flail, thickening, or calcification (B: dotted white lines). When the commissures are at an angle, additional commissural cines may be planned (B: solid white lines)

Figure 2

CMR assessment of MVP morphology and associated myocardial tissue changes. (A and B) In the three-chamber cines, it is evident that there is a P1 prolapse resulting in an MR jet directed towards the intra-atrial septum. It is also clear that the left atrium is dilated. The white arrow in B highlights MAD. (C and D) Velocity superimposition on cines using 4D flow CMR to highlight MR jet. In D, it is evident that the MR jet originates at P1/P2 level. (E and F) Myocardial tissue characterization reveals higher native T1 values and scar/fibrosis in the lateral wall on LGE imaging

Figure 3

Primary MR with congenital cleft mitral valve and normal mitral valve leaflet motion (Carpentier I). (A–C) In both short-axis and long-axis cines, at the level of the A2 leaflet, the anterior mitral valve leaflet is split but connected in a V-shape with a raphe in between. This raphe (white arrows) is seen in the LV outflow tract. (D) Mitral flow quantification using 4D flow and compensating for myocardial motion by using valve tracking. (E–G) 4D flow superimposed velocity demonstrates flow acceleration in the LV outflow tract during systole. Also, eccentric MR is seen, which is directed towards the lateral LA wall. (H) Aortic flow mapping using 4D flow data. (I) 4D flow streamlines in three-dimension demonstrate the flow acceleration in the LV outflow tract due to the MV raphe with a 2.2 m/s peak velocity. (J) Standard and two 4D flow methods to quantify MR demonstrate that it is at most moderate MR only

Figure 4

Role of CMR in ischaemic MR. This is a case of severe secondary MR and extensive transmural inferior myocardial infarction. This patient had a high degree of VT burden and needed an intra-cardiac defibrillator. LV filling pressure was high using LA volume and LV mass.

Figure 5

Standard MR quantification methods using CMR. (A) In the patient without VHD or a cardiac shunt, the ventricular SVs, aortic flow, and PA flow are all equal. (B) In the patient with MR and no cardiac shunt, the LV SV is increased due to the presence of MR. The RV SV, aortic flow, and PA flow all equal each other. The MR volume is calculated as LV SV − aortic flow. (C) In the patient with MR and AR and no cardiac shunt, the LV SV is increased due to the presence of MR and AR. Aortic flow now includes aortic forward SV and AR. AR volume can be measured directly using the diastolic flow of the aortic flow

Figure 6

Primary MR quantification (Carpentier type II). (A–C) Morphological assessment of the mitral valve is first made on cines. In these first three panels, it is evident that there is both anterior and posterior MVP, resulting in the dooming of both leaflets. In C, which is an extension of the short-axis LV volumetric assessment, it is clear that the prolapse is worse at the P1 and P2 levels. (D–F) On 4D flow velocity superimposition on top of cines, it is clear that the prolapse is resulting in an eccentric MR jet directed towards the intra-atrial septum. This jet is seen in E to cause flow reversal in upper pulmonary veins. (G) Three main methods of MR have been used to quantify MR, and they have excellent agreement between them. This builds confidence in reporting the degree of MR, which in this particular case is severe

Figure 7

Four-dimensional flow assessment in a patient with mitral valve replacement. (A) Diastolic mitral inflow streamlines. For mitral inflow, the reconstruction plane is below the MVR to avoid the artefacts due to it. (B) Both mitral and tricuspid regurgitation planes are tracked throughout the ventricular systole. (C) Both pulmonary and aortic flows are quantified to apply the conservation of mass principle to flow. (D) The flow volume across all four valves is in excellent agreement: this builds confidence in the MR regurgitation fraction (40%). In this case, the MR is severe, and the TR is mild

Figure 8

Recommended clinical pathway for the use of CMR for mitral valve disease assessment

Figure 9

MS assessment by CMR. (A and B) Cine images demonstrate restrictive mitral valve opening with flow acceleration seen as a de-phasing artefact through the papillary muscles. On the short-axis, cut-through at the narrowest opening during peak mitral inflow, the mitral valve area on planimetry was .8 cm², consistent with severe MS. Furthermore, the left atrium is significantly dilated again, suggesting raised LA pressures. (C) Native T1 values were higher than normal in the septum suggestive of myocardial changes. (D and E) Superimposed velocity vector using 4D flow displayed on top of cine images demonstrates the spatial location of the peak inflow velocities. (F) Quantification of mitral inflow velocities using 4D flow at the level of maximum velocities in the log-axis observed in D. The mean pressure gradient across the mitral valve was 20 mmHg—consistent with severe MS