上图1：CT平扫见遍布大脑后部白质和内囊后肢的双侧对称性低密度灶;
上图2：CT平扫见双侧对称性低密度灶，累及波及和小脑桥脑脚;
下图1：内囊后肢、胼胝体压部和枕叶白质双侧对称性长T2信号;
下图2：皮质脊髓束、孤束、小脑脚和小脑白质双侧对称性长T2信号;
上图3：由大脑后部白质向前逐渐减轻的双侧对称性长T2信号;
下图3：内侧丘系见长T2信号。
The involvement of the cerebellar and posterior cerebral white matter and the posterior limb of the internal capsule are typical features of heroin vapour inhalation but may not be specific for other toxic leukoencephalopathies. 累及小脑和大脑后部白质和内囊后肢是海洛因吸入中毒的典型特征，但对于其他脑白质病而言则非特异性。
上图：双侧大脑后部白质长T2信号，左侧枕叶后部长T2信号区MRS见NAA峰明显降低，乳酸峰升高，Cho峰无明显升高;
左下图：DWI见半卵圆中心高信号影;
右下图：ADC见与左下图相应位置低信号影。
Many chemotherapeutic agents have been associated with neurotoxicity. Diagnosis of
chemotherapy-induced neurotoxicity is based on three factors: known toxicities of an individual drug,the temporal relationship between drug administration and neurologic complication, and exclusion of other possible causes.
treatment: Discontinuation of the causative chemotherapy is the treatment of choice.Steroids may be used, but with unclear benefit.
由5-FU（5-氟尿嘧啶）引起的神经毒性
A图和B图DWI见双侧对称性大脑深部白质及胼胝体膝部和压部的高信号;
C图和D图T2见病灶仅呈稍高信号。
(A and MRI shows areas of restricted diffusion with corresponding ADC map hypointensity in the brachium pontis, splenium, and genu of the corpus callosum and in the
posterior centrum semiovale. (C) MRI shows changes in the fluid-attenuated inversion recovery (FLAIR) sequence. (D) MRI done 4 weeks later shows resolution
of changes FLAIR sequences.
Tacrolimus(他克莫司，FK-506)中毒
是一种器官移植后广泛运用的免疫抑制剂，它的神经系统副作用包括轻微的如头痛、震颤、感觉异常，严重的副作用如白质脑病发生在1-6％的移植后病人。中枢神经系统并发症和血药浓度没有必然联系，但减药或停药后症状和病灶可恢复。
12岁的女孩接受原位肝移植后接受他克莫司治疗，6月后出现癫痫发作，血压正常，脑脊液正常，他克莫司血浓度在正常范围内。
下图：
A-F,显示顶叶、脑室周围、脑干、小脑异常信号。
G-I: 他克莫司减量16天后复查，示病灶减少，小脑、脑干病灶消失。
J-K:5月复查，无明显病灶，遗留活检病灶。
A, In the biopsy fragments, the cerebral white matter shows a normal aspect with ample staining for myelin, absence of inflammatory infiltrate and (in contrast to PML) absence of enlarged nuclei of glial cells. Occasional perivascular macrophages (arrow), however, contain granular, blue-staining material, consistent with myelin debris. (Combined Luxol Fast Blue and Hematoxylin-Eosin staining; original magnification x630).
B, Electron microscopy, performed on material retrieved from the paraffin block, reveals multilamellar particles in the perivascular macrophages, corroborating the myelin nature of these granules.
参考文献：Severe Tacrolimus Leukoencephalopathy after Liver Transplantation （American Journal of Neuroradiology 24:2085-2088, November-December 2003）
CO中毒后造成低氧血症及脑组织缺血， MR主要表现为：
（1） 双侧苍白球长T1 与长T2异常信号，卵圆形，直径＜1cm，不强化；（熊猫眼）
（2） 急性与亚急性期双侧大脑白质区脑水肿，呈长T1 与长T2信号，以脑室周围白质为主；
（3） 侧脑室前、后角周围月晕状缺血性脱髓鞘改变，呈长T1 与长T2，可长期存在；
（4） 广泛性脑萎缩，以髓质性为主，双侧脑室扩大，脑池扩大。
