Machnig T, Koroneos A, Engels G, Bachmann K, Simm C, Wilke N, Ellermann J, Zhang J, Ya X, Merkel H
II. Med. Klinik, Universität Erlangen/Nürnberg.
Z Kardiol. 1994 Nov;83(11):840-50.
With the advent of ultrafast Magnetic Resonance Imaging (MRI), it is now possible to produce images with high temporal resolution. This gives the opportunity to record the passage of the paramagnetic contrast material Gadolinium-DTPA through the tissue of the heart muscle, yielding information on regional myocardial perfusion. We assessed the accuracy of MRI to detect and quantify reductions in coronary flow secondary to stenosis in dogs and patients. Regional blood flow was measured in dogs by left atrial injection of microspheres labeled with different radioactive isotopes. Signal intensity (SI) curves were generated in regions of interest over the myocardium and the cavum of the left ventricle. A newly developed two-compartment model based on the indicator-dilution method was used for interpretation of the SI-curves. In an optimization process the free parameters of the model equation were fitted to the measured SI-curves. The following flow parameters were determined: model parameter Q*, time to peak intensity (T), maximum signal intensity (SImax) and mean transit time (MTT) as calculated from a gamma variate fit. Absolute blood flow values were calculated for the parameters MTT and Q* assuming that the intravascular volume represents 10% of the total myocardial tissue volume. Measurements were performed on a 1.5 T Magnetom SP (Siemens AG, Erlangen) using a Turbo Flash sequence (TR = 6.5 ms, TE = 3 ms, TI = 100 ms, Flip Winkel = 9 degrees). Endsystolic images (voxel size = 1.8, 2.7, 15 mm3) were taken with an 18-cm Helmholtz surface coil in the short-axis view. A Gd-DTPA bolus (0.05 mmol/kg) was injected into the left atrium of 3 anesthetized closed-chest dogs. From the myocardial SI-curves the different parameters of myocardial perfusion were compared with flow assessed by microsphere injection over a wide range of myocardial blood flows (from 0.04 ml/min/g to 7.6 ml/min/g). A third-order polynominal fit showed a good correlation for the parameter Q* and MTT, whereas T and SImax were found to have a poor correlation. The linear regression analysis for a limited range of < 2 ml/min/g showed a superior estimation of myocardial perfusion for the parameter Q* than MTT. Blood flow > 2 ml/min/g was significantly underestimated by the MRT-measurements, but the parameter Q* showed the smallest amount of the divergent changes.(ABSTRACT TRUNCATED AT 400 WORDS)
随着超快磁共振成像（MRI）的出现，现在能够生成具有高时间分辨率的图像。这使得有机会记录顺磁性造影剂钆-二乙三胺五乙酸（Gadolinium-DTPA）通过心肌组织的过程，从而获得有关局部心肌灌注的信息。我们评估了MRI检测和量化狗和患者因狭窄导致的冠状动脉血流减少的准确性。通过向左心房注射标记有不同放射性同位素的微球来测量狗的局部血流。在心肌和左心室腔的感兴趣区域生成信号强度（SI）曲线。使用基于指示剂稀释法新开发的双室模型来解释SI曲线。在优化过程中，将模型方程的自由参数拟合到测量的SI曲线上。确定了以下血流参数：模型参数Q*、达到峰值强度的时间（T）、最大信号强度（SImax）以及根据伽马变量拟合计算的平均通过时间（MTT）。假设血管内体积占心肌组织总体积的10%，计算MTT和Q参数的绝对血流值。使用Turbo Flash序列（TR = 6.5 ms，TE = 3 ms，TI = 100 ms，翻转角 = 9度）在1.5 T Magnetom SP（西门子公司，埃尔朗根）上进行测量。在短轴视图中使用18厘米的亥姆霍兹表面线圈采集收缩末期图像（体素大小 = 1.8, 2.7, 15 mm3）。将钆-二乙三胺五乙酸团注（0.05 mmol/kg）注入3只麻醉的闭胸狗的左心房。从心肌SI曲线中，在广泛的心肌血流范围（从0.04 ml/min/g至7.6 ml/min/g）内，将心肌灌注的不同参数与通过微球注射评估的血流进行比较。三阶多项式拟合显示参数Q和MTT具有良好的相关性，而T和SImax的相关性较差。对于< 2 ml/min/g的有限范围进行线性回归分析表明，参数Q对心肌灌注的估计优于MTT。MRT测量显著低估了> 2 ml/min/g的血流，但参数Q显示出最小的差异变化量。（摘要截短为400字）
