MAGNETIZATION-TRANSFER - THEORY AND CLINICAL-APPLICATIONS IN NEURORADIOLOGY
MAGNETIZATION-TRANSFER - THEORY AND CLINICAL-APPLICATIONS IN NEURORADIOLOGY
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DOI：
10.1148/radiographics.14.2.8190954
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发表时间：
1994-03-01
期刊：
影响因子：
5.5
通讯作者：
SCHNALL, MD
中科院分区：
文献类型：
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作者：
GROSSMAN, RI;GOMORI, JM;SCHNALL, MD
磁化传递是一种用于改善磁共振（MR）成像中图像对比度的新技术，其基础是应用非共振射频脉冲并观察其对MR图像的影响，以及测量应用和不应用脉冲的信号强度（即磁化传递比[MTR]）。MTR可用于检测标准MR技术可能可见或不可见的脑实质结构状态变化。使用MTR可以将多发性硬化病变亚分类为MTR极低（脱髓鞘病变）和MTR轻微降低（水肿病变）。在沃勒变性的情况下，MTR的使用似乎可以可靠地检测到MR成像甚至光学显微镜无法检测到的变化。在感染人类免疫缺陷病毒的情况下，MTR似乎表明白色物质的大分子结构保持完整，直到病程的相对晚期。在转移性疾病的情况下，脑病变的MTR指示超出标准MR图像上所见病变范围的结构变化。这些发现可能是由于慢性水肿，髓鞘丢失，也许以前未被发现的肿瘤。除了作为一种提供对比的新方法之外，磁化转移技术还能够对组织和病理实体进行半定量、可再现的表征，这可以大大提高MR成像的特异性。
Magnetization transfer, a new technique for improving image contrast in magnetic resonance (MR) imaging, is based on application of off-resonance radio-frequency pulses and observing their effects on MR images, as well as measuring the signal intensity with and without application of the pulses (ie, magnetization transfer ratio [MTR]). MTRs can be used to detect changes in the structural status of brain parenchyma that may or may not be visible with standard MR techniques. Use of MTRs may allow subcategorization of multiple sclerosis lesions into those with very low MTR (demyelinated lesions) and slightly decreased MTR (edematous lesions). In cases of wallerian degeneration, use of MTRs appears to allow reliable detection of changes undetectable with MR imaging or even light microscopy. In cases of infection with human immunodeficiency virus, MTRs seem to indicate that the macromolecular structure of white matter remains intact until relatively late in the course of disease. In cases of metastatic disease, MTRs of brain lesions indicate structural changes beyond the extent of the lesions seen on standard MR images. These findings may be due to chronic edema, myelin loss, and perhaps previous undetected tumor. In addition to being a new method of providing contrast, the magnetization transfer technique enables semiquantitative, reproducible characterization of tissue and pathologic entities, which could substantially improve the specificity of MR imaging.