Cardiac MR PET CT Program and Cardiac Ultrasound Laboratory, Division of Cardiology, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA.
Circ Cardiovasc Imaging. 2013 Sep;6(5):784-9. doi: 10.1161/CIRCIMAGING.113.000561. Epub 2013 Jul 19.
Mitral valve (MV) enlargement is a compensatory mechanism capable of preventing functional mitral regurgitation (FMR) in dilated ventricles. Total leaflet area and its relation with closure area measured by 3-dimensional (3D) echocardiography have been related to FMR. Whether these parameters can be assessed with other imaging modalities is not known. Our objectives are to compare cardiac computed tomography (CT)-based measurements of MV leaflets with 3D echocardiography and determine the relationship of these metrics to the presence of FMR.
We used 2 cohorts of patients who had cardiac CT to measure MV total leaflet, closure, and annulus areas. In cohort 1 (26 patients), we validated these CT metrics to 3D echocardiography. In cohort 2 (66 patients), we assessed the relation of MV size with the presence of FMR in 3 populations: heart failure with FMR, heart failure without FMR, and normal controls. Cardiac CT and 3D echocardiography produced similar results for total leaflet (R(2)=0.97), closure (R(2)=0.89), and annulus areas (R(2)=0.84). MV size was the largest in heart failure without FMR compared with controls and patients with FMR (9.1 ± 1.7 versus 7.5 ± 1.0 versus 8.1 ± 0.9 cm(2)/m(2); P<0.01). Patients with FMR had reduced ratios of total leaflet to closure areas and total leaflet to annulus areas when compared with patients without FMR (P<0.01).
MV size measured by CT is comparable with 3D echocardiography. MV enlargement in cardiomyopathy suggests leaflet adaptation. Patients with FMR have inadequate adaptation as reflected by decreased ratios of leaflet area and areas determined by ventricle size (annulus and closure areas). These measurements provide additional insight into the mechanism of FMR.
二尖瓣（MV）扩大是一种代偿机制，能够防止扩张心室中的功能性二尖瓣反流（FMR）。通过三维（3D）超声心动图测量的总瓣面积及其与瓣叶闭合面积的关系与 FMR 相关。尚不清楚是否可以使用其他成像方式评估这些参数。我们的目的是比较基于心脏计算机断层扫描（CT）的 MV 瓣叶测量值与 3D 超声心动图，并确定这些指标与 FMR 存在的关系。
我们使用了两组接受心脏 CT 检查以测量 MV 总瓣叶、闭合和瓣环面积的患者。在队列 1（26 例患者）中，我们对 CT 测量值与 3D 超声心动图进行了验证。在队列 2（66 例患者）中，我们评估了 MV 大小与 3 种人群中 FMR 存在的关系：心力衰竭伴 FMR、心力衰竭不伴 FMR 和正常对照组。心脏 CT 和 3D 超声心动图对总瓣叶（R（2）=0.97）、闭合（R（2）=0.89）和瓣环面积（R（2）=0.84）的测量结果相似。与对照组和 FMR 患者相比，心力衰竭不伴 FMR 的患者 MV 较大（9.1±1.7 比 7.5±1.0 比 8.1±0.9 cm（2）/m（2）；P<0.01）。与心力衰竭不伴 FMR 的患者相比，FMR 患者的总瓣叶与闭合面积比和总瓣叶与瓣环面积比降低（P<0.01）。
CT 测量的 MV 大小与 3D 超声心动图相当。心肌病患者的 MV 增大表明瓣叶适应性增加。FMR 患者的瓣叶面积和心室大小（瓣环和闭合面积）决定的面积之间的比值降低，表明适应性不足。这些测量值提供了对 FMR 机制的更多了解。
