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目的分析颅内表皮样囊肿(ECs)的DWI特征,评价“T2shine-through”效应。方法手术病理证实15例ECs,其中3例术后复查残留。测量ECs、深部脑白质、脑脊液(CSF)的表观弥散系数(ADC)值;比较DWI与FLAIR对病灶的显示。结果(1)15例病灶DWI均呈高信号,ADC值(0.80~1.23)×10-3mm2/s,平均(1.05±0.14)×10-3mm2/s;深部脑白质ADC值(0.74~1.09)×10-3mm2/s,平均(0.88±0.09)×10-3mm2/s;CSF的ADC值(2.98~3.78)×10-3mm2/s,平均(3.31±0.21)×10-3mm2/s;ECs的ADC值低于CSF(P<0.001),高于脑白质(P=0.005),与脑灰质近似。(2)15例病人中,在FLAIR上6例病灶轮廓清楚,DWI上12例病灶轮廓清楚,对病灶轮廓勾画存在显著性差异,P=0.025(χ2值5.00)。(3)5例复查病人中,2例DWI上没有显示高信号病灶,3例病变区小的高信号病灶。结论颅内表皮样囊肿ADC值降低不明显,与DWI高信号不匹配,是由于增强T2效应。DWI能最好的显示病灶,对小病灶检测、术后评估优于其它成像序列。
Objective To analyze the DWI features of intracranial epidermoid cysts (ECs) and evaluate the “T2shine-through” effect. Methods Fifteen cases of ECs were confirmed by surgical pathology. Three of them were examined after operation. Apparent diffusion coefficient (ADC) values of ECs, deep white matter and cerebrospinal fluid (CSF) were measured. The comparison between DWI and FLAIR was made. Results (1) The DWI of all the 15 cases showed high signal, the ADC value was 0.80-1.23 × 10-3mm2 / s, the average was 1.05 ± 0.14 × 10-3mm2 / s, the ADC value of deep white matter was 0.74-1.09, (0.88 ± 0.09) × 10-3mm2 / s, ADC value of CSF (2.98-3.78) × 10-3mm2 / s, average (3.31 ± 0.21) × 10-3mm2 / s and ECs ADC value was lower than CSF (P <0.001), higher than that of white matter (P = 0.005), similar to gray matter. (2) Of the 15 patients, the outline of 6 lesions on FLAIR was clear, and the outline of 12 lesions on DWI was clear. There was a significant difference in outline of the lesions, P = 0.025 (χ2 = 5.00). (3) Of the 5 patients reviewed, 2 cases showed no high signal lesions on DWI and 3 cases had small high signal lesions on DWI. Conclusion The decrease of ADC value of intracranial epidermoid cyst is not obvious, and it does not match the high signal of DWI, which is due to the enhancement of T2 effect. DWI can best display the lesion, small lesions detection, postoperative evaluation is better than other imaging sequences.