帕金森病 (Parkinson's disease,PD)是一种中脑黑质多巴胺神经元的变性死亡所致黑织纹状体缺失而引起神经变性疾病。目前帕金森病还是根据病人的临床表现来进行诊断的，而临床症状表现明显时已经属于晚期，因此迫切需要寻找新的生物指标来对帕金森疾病进行诊断。在本研究中，作者采用了一种新的非侵入性的磁共振成像技术（APTw MRI）从分子水平对帕金森并进行了系统的研究，并与弥散张量磁共振成像方法进行了定量对比分析。研究发现相对于正常对照组而言， APTw 与FA在黑质区均呈现信号降低的趋势，在硬膜与尾状核区APTw 信号降低而FA信号没有明显差异。因此，在帕金森病的鉴别诊断上，相对于常规弥散张量成像而言，APTw磁共振成像技术提供了更多医学影像信息，具有更明显的优势。相对于作者的前期工作而言（首次将APTw应用到PD的研究），该研究进一步在分子水平上对帕金森疾病的神经变性进行了探讨，具有重要的临床价值。
(A) substantia nigra (green), (B) globus pallidus (blue), putamen (yellow) and caudate (red).
图2：PD患者与正常对照的磁共振图像：PD 病人（上）: (A) FLAIR (B) APT (C) FA (D) MD；正常对照（下）：(E) FLAIR (F) APT (G) FA (H) MD 。相对于正常对照而言，在黑质区域PD病人（上）的APTw信号明显降低，而FA在图像上信号差异相对较小，但存在组别差异。
Parkinson's disease (PD) is a neurodegenerative disorder characterized by nigrostriatal cell loss. To date, the diagnosis of PD is still based primarily on the clinical manifestations, which may be typical and obvious only in advanced-stage PD. Thus, it is crucial to find a reliable marker for the diagnosis of PD. We conducted this study to assess the diagnostic efficiency of chemical exchange saturation transfer (CEST) imaging and diffusion-tensor imaging (DTI) in PD at 3 T by evaluating changes on substantia nigra and striatum. Twenty-three PD patients and twenty-three age-matched normal controls were recruited. All patients and controls were imaged on a 3-T MR system, using an eight-channel head coil. CEST imaging was acquired in two transverse slices of the head, including substantia nigra and striatum. The magnetization transfer ratio asymmetry at 3.5 ppm, MTRasym(3.5 ppm), and the total CEST signal intensity between 0 and 4 ppm were calculated. Multi-slice DTI was acquired for all the patients and normal controls. Quantitative analysis was performed on the substantia nigra, globus pallidus, putamen, and caudate. The MTRasym(3.5 ppm) value, the total CEST signal intensity, and fractional anisotropy value of the substantia nigra were all significantly lower in PD patients than in normal controls (P = 0.003, P = 0.004, and P < 0.001, respectively). The MTRasym(3.5 ppm) values of the putamen and the caudate were significantly higher in PD patients than in normal controls (P = 0.010 and P = 0.009, respectively). There were no significant differences for the mean diffusivity in these four regions between PD patients and normal controls. In conclusion, CEST MR imaging provided multiple CEST image contrasts in the substantia nigra and the striatum in PD and may be superior to DTI in the diagnosis of PD.
||参考文献：Li C, et al. Chemical Exchange Saturation Transfer MR Imaging is Superior to Diffusion-Tensor Imaging in the Diagnosis and Severity Evaluation of Parkinson's Disease: A Study on Substantia Nigra and Striatum. Front Aging Neurosci. 2015;7:198.