Imaging protocols and methodology for assessment of MR via CMR
The ASE/ACC/AHA guidelines for the assessment of native valvular
regurgitation highlight the importance of evaluating not only the
severity of the regurgitant but also the hemodynamic effects the
valvular lesion has on the LV as well as the left
atrium.(4,9,28) Evaluating LV function
and structure via cine images and flow imaging via phase contrast
imaging is the cornerstone of the CMR evaluation of MR.
Initial imaging protocols for evaluating MR should follow the Society of
Cardiac Magnetic Resonance (SCMR) recommendations and start with
standard cine images. Steady state free-precession (SSFP) images should
be taken in standard views: in the four-chamber, two-chamber and
three-chamber views.
To optimize visualization of the mitral valve apparatus, a contiguous
stack of cines should be taken perpendicular to the mitral valve and
transect the principal line of cooptation. These should be contiguous
with zero gap, and a slice thickness of 5-8 mm should be used to
maximize special resolution with a goal temporal resolution of under 50
milliseconds.
Using this protocol, CMR can view the entire mitral valve interface and
cooptation of the anterior and posterior leaflets along all three
scallop-interfaces- from the lateral interface near the appendage, to
the medial interface.
Additionally, standard cine short-axis LV imaging should be performed to
evaluate LV function, but should be extended to cover the mitral valve.
In addition to cine imaging of the LV, the CMR protocol in patients with
MR should include flow imaging through the aortic valve using the
standard phase-contrast, velocity encoded methods. The SCMR
recommendations include standard parameters for flow imaging.
(4,7,10,29)