ADC比值鉴别诊断儿童后颅窝肿瘤

Differential diagnosis of pediatric posterior fossa tumors using apparent diffusion coefficient ratios

目的探讨肿瘤与正常脑组织表观扩散系数(ADC)比值诊断儿童后颅窝肿瘤的价值。方法回顾性分析60例经手术病理证实的儿童后颅窝肿瘤,其中毛细胞型星形细胞瘤(PA)30例,髓母细胞瘤(MB)18例,室管膜瘤12例。术前均接受MR检查,包括DWI。测定肿瘤实性部分、正常脑组织ADC值,计算肿瘤与正常脑组织ADC比值。利用ROC曲线确定ADC比值对肿瘤鉴别诊断的最佳阈值。结果肿瘤与正常脑组织ADC比值PA为2.33±0.39,MB为0.96±0.19,室管膜瘤为1.52±0.26,差异有统计学意义(P均<0.05)。ROC曲线分析显示区分室管膜瘤与PA的肿瘤与正常脑组织ADC比值最佳阈值为1.87,其敏感度为91.7%,特异度为86.7%;区分MB与室管膜瘤的肿瘤与正常脑组织ADC比值最佳阈值为1.19,其敏感度为88.9%,特异度为91.7%。结论肿瘤与正常脑组织ADC比值对常见儿童后颅窝肿瘤具有较高的鉴别诊断价值。

Objective To evaluate tumor and normal brain apparent diffusion coefficient（ADC）ratios in differential diagnosis of pediatric posterior fossa tumors.Methods Totally 60 patients with pediatric posterior fossa tumors confirmed by surgery and pathology were retrospectively reviewed.There were 30 pilocytic astrocytomas（PA）,18 medulloblastomas（MB）,and 12 ependymomas.All the patients underwent preoperative MRI,including DWI.ADC values were measured on the solid partial of the tumor and normal brain parenchyma.The solid partial of the tumor and normal brain ADC ratios were calculated.ROC curve analysis was performed to generate the best thresholds of tumor and normal brain ADC ratios to distinguish tumors.Results The mean tumor and normal brain ADC ratios were statistically significant difference among PA（2.33±0.39）,MB（0.96±0.19）and ependymoma patients（1.52±0.26,all P〈0.05）.The ROC curve showed that the best thresholds of tumor and normal brain ADC ratios to distinguish PA from ependymomas was 1.87 with sensitivity of 91.7% and specificity of 86.7%.The best thresholds of tumor and normal brain ADC ratios to distinguish MB from ependymomas was 1.19 with sensitivity of 88.9% and specificity of 91.7%.Conclusion The tumor and normal brain ADC ratios are useful in differential diagnosis of common childhood posterior fossa tumors.