McGowan J C, Schnall M D, Leigh J S
Department of Radiology, Hospital of the University of Pennsylvania, Philadelphia 19104.
J Magn Reson Imaging. 1994 Jan-Feb;4(1):79-82. doi: 10.1002/jmri.1880040116.
Magnetization transfer contrast (MTC) can be generated in magnetic resonance images of water-containing macromolecular structures. Results obtained with the pulsed off-resonance saturation technique for achieving MTC are presented, allowing comparison of this technique with others. The magnetization transfer effect is demonstrated in newborn piglet brain and bovine muscle tissue, as well as in human subjects. MTC increases nonlinearly with the duty cycle of the off-resonance irradiation, approaching a maximum value corresponding to continuous irradiation. However, approximately half of the available contrast can be obtained at a given saturation offset frequency, with 16% irradiation duty cycle. Examples of MTC in various human tissues demonstrate the specificity of this technique at power levels within U.S. Food and Drug Administration guidelines. Plots of MTC versus the irradiation offset frequency demonstrate the effects of magnetization transfer and are compared with the curve generated by a control phantom that does not show magnetization transfer. Magnetization transfer imaging with pulsed off-resonance saturation is effective and easily implemented and may be useful in the investigation of saturation transfer phenomena in tissue.
磁化传递对比（MTC）可在含水体大分子结构的磁共振图像中产生。本文展示了利用脉冲非共振饱和技术实现MTC所获得的结果，以便将该技术与其他技术进行比较。在新生仔猪脑、牛肌肉组织以及人体受试者中均证实了磁化传递效应。MTC随非共振照射的占空比呈非线性增加，接近与连续照射相对应的最大值。然而，在给定的饱和偏移频率下，以16%的照射占空比可获得约一半的可用对比度。各种人体组织中MTC的实例表明，该技术在美国食品药品监督管理局规定的功率水平下具有特异性。MTC与照射偏移频率的关系图展示了磁化传递的效果，并与未显示磁化传递的对照体模所生成的曲线进行了比较。采用脉冲非共振饱和的磁化传递成像有效且易于实施，可能有助于研究组织中的饱和传递现象。
