Kjaer L, Thomsen C, Henriksen O, Ring P, Stubgaard M, Pedersen E J
Department of Magnetic Resonance, Hvidovre Hospital, Denmark.
Acta Radiol. 1987 May-Jun;28(3):345-51.
Several circumstances may explain the great variation in reported proton T1 and T2 relaxation times usually seen. This study was designed to evaluate the accuracy of relaxation time measurements by magnetic resonance imaging (MRI) operating at 1.5 tesla. Using a phantom of nine boxes with different concentrations of CuSO4 and correlating the calculated T1 and T2 values with reference values obtained by two spectrometers (corrected to MRI-proton frequency = 64 MHz) we found a maximum deviation of about 10 per cent. Measurements performed on a large water phantom in order to evaluate the homogeneity in the imaging plane showed a variation of less than 10 per cent within 10 cm from the centre of the magnet in all three imaging planes. Changing the gradient field strength apparently had no influence on the T2 values recorded. Consequently diffusion processes seem without significance. It is concluded that proton T1 and T2 relaxation times covering the majority of the biologic range can be measured by MRI with an overall accuracy of 5 to 10 per cent. Quality control studies along the lines indicated in this study are recommended.
有几种情况可以解释通常所见的质子T1和T2弛豫时间报告中的巨大差异。本研究旨在评估1.5特斯拉磁共振成像（MRI）测量弛豫时间的准确性。使用一个装有不同浓度硫酸铜的九个盒子的模型，并将计算出的T1和T2值与两台光谱仪获得的参考值（校正为MRI质子频率 = 64 MHz）相关联，我们发现最大偏差约为10%。为了评估成像平面的均匀性，在一个大的水体模上进行的测量显示，在所有三个成像平面中，距磁体中心10厘米范围内的变化小于10%。改变梯度场强度显然对记录的T2值没有影响。因此，扩散过程似乎没有意义。得出的结论是，MRI可以测量覆盖大部分生物学范围的质子T1和T2弛豫时间，总体准确度为5%至10%。建议按照本研究中指出的思路进行质量控制研究。
