[Value of nuclear magnetic resonance in XXXX . Approach to intraventricular hemodynamics].

@entity1 @entity384 @entity296 @entity299
The value of magnetic resonance imaging (MRI) with multiechoes spin-echo sequences was investigated in 22 @entity1 with @entity384 (group I) and 25 normal subjects serving as controls (group II). The results of MRI in group I were compared with those of echocardiography and radionuclide ventriculography. Measurements of left ventricular dimensions at echography and MRI showed a tendency, with MRI, to overestimate wall thickness and underestimate ventricular diameter. Thus, for diastolic LV we had 63.8 +/- 10.5 mm with MRI vs 70.6 +/- 7.6 mm with echography, the corresponding figures for posterior wall thickness being 112 +/- 1.4 mm vs 9.9 +/- 1.1 mm respectively. These differences seem to be due to MRI introducing a partial volume effect dependent on the thickness of slices and of their orientation in relation to the @entity299 . MRI evaluation of left ventricular function by calculation of myocardial fibre shortening fractions correlated poorly with the echocardiographic value of the same parameter and with the radionuclide ejection fraction (r = 0.58 and 0.575 respectively; p less than 0.05). For better quantification of the cardiac pump function, planimetry of the endocardial contour during diastole and systole is required. It would seem that the value of MRI resides in the possibility it offers to explore left intraventricular haemodynamics by studying the "flow signal" obtainable from multiechoes sequences at different moments of the cardiac cycle. During systole, we found a left intraventricular signal that was reinforced on even echoes and much more intense in @entity296 @entity1 (scores = 1.61 +/- 1.06) than in controls (score = 0.77 +/- 0.7; p less than 0.01). The intensity score for this signal correlated with the ejection fraction in group I subjects (r = 0.82).
