多发性硬化脑内病灶的扩散张量成像

Diffusion tensor imaging in characterizing plaques of multiple sclerosis

目的研究多发性硬化(MS)的脑内病灶在磁共振扩散张量成像(DTI)上的主要特征,量化分析不同时期病灶的ADC值的差异,探讨DTI在反映MS病理变化中的价值。方法应用3.0 T磁共振设备对34例MS病人行常规头颅MRI和DTI检查,根据病灶有无强化和在T1WI上的信号强度,进行急慢性期病灶的分组。分析不同时期MS病灶在DTI后处理所获得的DWI、ADC、FA图上的特征,并测量各组病灶的ADC值。结果35个急性期病灶中的33个病灶(94.3%)于DWI上呈高信号,5个环形强化病灶在DWI上亦呈环形高信号。急、慢性期病灶的ADC值均升高。慢性期病灶的ADC值明显高于急性期病灶[(12.43±3.78)×10-4 mm2/s∶(10.10±2.28)×10-4 mm2/s,P=0.001]。急性期环形强化病灶的ADC值较非环形强化病灶的高,慢性期T1WI低信号病灶的ADC值较T1WI等信号病灶的高,T1WI明显低信号病灶的ADC值最高。急、慢性期病灶的FA值均降低。FA图能够清晰显示纤维通路上的病灶和纤维束的中断,定位上明显优于常规MRI。病灶于FA图上显示的范围较常规MRI T2WI上显示的大。结论DTI可以反映MS不同时期病灶的病理变化,为观测疾病演变和评价临床疗效提供有效的指标。

Objective To characterize the plaques of multiple sclerosis （MS） using diffusion tensor imaging, to explore difference in ADC between acute and chronic MS plaques. Methods Conventional MRI and DTI examinations were performed in 34 clinically defined MS patients. The stages of plaques were determined according to Gd-enhancement pattern and the signal intensity on T1-weighted images. ADC and FA map were derived from DTI raw data and the ADC values of the MS plaques were measured. Results On DWI, 33 of 35 （94.3%） acute lesions showed hyperintense and 5 lesions showed ring-like hyperintense.Both acute and chronic lesions showed increased ADC and decreased FA. The mean ADC value of chronic lesions was significantly higher than that of acute lesions[ （ 12.43±3.78 ）×10^-4 mm^2/s vs. （ 10.10±2.28 ） ×10^-4 mm^2/s, P=-0.001 ）. Ring-enhancing lesion showed higher ADC than non-ring enhancing lesions. In chronic lesions, the mean ADC of T1-hypointense lesions was significantly higher than that of T1-isointense lesions, The severe T1-hypointense lesions revealed the highest ADC. Disruption of fiber pathway were detected on FA map with good contrast of gray and white matter, the size of lesions on FA＇maps was increased compared with that on T2-weighted images. Conclusion DTI technique can detect pathological changes in various types of MS lesions in vivo. It is a sensitive and efficient method to monitor MS plaques and assessing therapies in MS patients.