Globits S, Higgins C B
Department of Radiology, University of California, San Francisco.
Am Heart J. 1995 Feb;129(2):369-81. doi: 10.1016/0002-8703(95)90020-9.
MRI has developed very rapidly and now provides anatomic and functional information in cases of valvular heart disease. MRI has several important attributes that make it advantageous for the evaluation of valvular heart disease. First, the natural contrast between flowing blood and surrounding cardiovascular structures provides sharp delineation of endocardial and epicardial borders without the need for contrast media. This feature in combination with the essential three-dimensional nature of this imaging technique allows precise quantification of cardiac volumes, function, and mass without the use of any assumed formulas or geometric models. Second, blood flow-sensitive GRE techniques are able to identify areas of turbulent flow caused by stenotic or regurgitant valves. With this technique regurgitant jets can be visualized and semiquantitative grading can be performed as with color Doppler. Third, recently developed velocity-encoded techniques permit measurements of blood flow velocities across stenotic native and prosthetic heart valves and retrograde flow caused by regurgitation. Moreover, the close interstudy reproducibility of measurements of cardiac dimensions and valvular regurgitation suggests a role in assessing the effect of therapeutic interventions.
磁共振成像（MRI）发展非常迅速，目前可在心脏瓣膜病病例中提供解剖学和功能信息。MRI具有几个重要特性，使其在评估心脏瓣膜病方面具有优势。首先，流动血液与周围心血管结构之间的天然对比可清晰勾勒心内膜和心外膜边界，无需使用造影剂。这一特性与该成像技术固有的三维特性相结合，可在不使用任何假定公式或几何模型的情况下精确量化心脏容积、功能和质量。其次，血流敏感梯度回波（GRE）技术能够识别由狭窄或反流瓣膜引起的湍流区域。通过该技术，反流束可被可视化，并且可像彩色多普勒那样进行半定量分级。第三，最近开发的速度编码技术可测量流经狭窄的天然和人工心脏瓣膜的血流速度以及反流引起的逆向血流。此外，心脏尺寸和瓣膜反流测量在不同研究之间具有高度的可重复性，这表明其在评估治疗干预效果方面具有作用。
