Cesana P, Luzzi M, Pertusio P, Spandonari T
Servizio di Fisica Sanitaria, Ospedale San Giovanni Battista e della Città di Torino, Genova.
Radiol Med. 1989 Jun;77(6):684-8.
The intensity of MR signal depends on several parameters, such as proton density [N(H)], relaxation times (T1 and T2), repetition time (TR), and echo time (TE). A theoretical model describes this dependence, which is currently employed for image optimization. It allows the evaluation of image contrast once the tissue parameters are known. The above-mentioned theoretical model was tested with the use of CuSO4 samples at various concentrations for which T1 and T2 values were known from the literature. Our unit was an ESATOM MR 5000 which employed a 0.5 Tesla magnetic field. We used spin-echo sequences with TR = 500, 1000 ms and TE ranging from 50 to 150 ms. Signal intensity was measured both by direct access to the data matrix and with the use of the pixel intensity calculation program for regions of interest. The difference in the signals corresponding to the various samples were determined to evaluate the contrast. Our results are in strict agreement with those from the theoretical model. The latter can thus be employed for image optimization.
磁共振信号强度取决于多个参数，如质子密度[N(H)]、弛豫时间（T1和T2）、重复时间（TR）和回波时间（TE）。一个理论模型描述了这种依赖性，目前该模型用于图像优化。一旦组织参数已知，它就能评估图像对比度。上述理论模型通过使用不同浓度的CuSO4样品进行了测试，其T1和T2值可从文献中获取。我们的设备是一台ESATOM MR 5000，采用0.5特斯拉磁场。我们使用了TR = 500、1000 ms且TE范围为50至150 ms的自旋回波序列。通过直接访问数据矩阵以及使用感兴趣区域的像素强度计算程序来测量信号强度。确定对应于各种样品的信号差异以评估对比度。我们的结果与理论模型的结果严格一致。因此，后者可用于图像优化。
