儿童异染性脑白质营养不良的MRI表现

目的 观察异染性脑白质营养不良（MLD）的特征性表现。方法 回顾分析我院经生化检查证实的MLD共11例，观察MRI上脑内白质病变的部位和特殊结构（白质纤维束、丘脑、胼胝体）受累的情况。结果 11例均表现为双侧脑室周围白质T2WI对称高信号，10例双侧半卵圆中心T2WI对称高信号；4例累及皮层下白质。8例累及胼胝体膝部，9例累及压部，两者同时受累为8例；7例累及内囊后肢，4例累及外囊，4例累及脑干皮质脊髓束（3例中脑，1例桥脑）。1例累及小脑白质，8例半卵圆中心T2WI有虎纹征，8例T2WI丘脑呈低信号；5例侧脑室扩大，1例全脑萎缩。结论 MLD的典型表现为双侧半卵圆中心和侧脑室周围白质T2WI对称高信号，早期皮层下白质不受累，胼胝体膝部和压部受累为重要征象；另外征象包括脑干皮质脊髓束和内、外囊受累及虎纹征。

MRI appearance of metachromatic leukodystrophy in children

Objective To analyze the chara cteristic finding of metachromatic leukodystrophy (MLD) on MR images. Methods Eleven patients with biochemicall y proved MLD were studied retrospectively for the extent of white matter abnormalities and the in volvement of specific structures (such as corpus callosum, white matter tract, a nd thalami). Result All 11 cases in the periventricular white m atter and 10 cases in centrum semiovale showed a symmetric confluent high intens ity on T_2-weighted images. Involvement of subcortical U-fibers was present i n 4 late-stage cases. Other sites of involvement were the genu (n=8) and s plenium (n=9) of the cor pus callosum (both n=8), the posterior limbs of internal capsule (n=7), external capsule (n=4), the descending pyramidal tracts (pons in 1, midbrain in 3), and the cerebellar white matter (n=1). A tigroid pattern was found in the centru m se miovale in 8 cases. Nine cases appeared low signal intensity on T_2-weighted i mag es in the thalami; There were 5 cases with mild ventriculomegaly and 1 case with diffuse brain atrophy. Conclusion The typical MR feature of M LD is a bilatera l and symmetrical high signal intensity on T_2-weighted images in periventricu lar and centrum semiovale white matter with initial sparing of the subcortical U -fi ber, and both the genu and splenium of corpus callosum involvement. Besides, the tigroid pattern in the centrum semiovale and involvement of the internal capsul e, external capsule, and corticospinal tract are frequent additional features.