表观扩散系数对小儿髓母细胞瘤的诊断价值

Diagnostic value of apparent diffusion coefficient for medulloblastoma in children

目的:探索表观扩散系数(ADC)值对小儿髓母细胞瘤的诊断价值。方法:33例小儿后颅窝肿瘤,其中髓母细胞瘤18例,星形细胞瘤15例,患儿均接受MRI的扩散加权成像(DWI)扫描,分析DWI图像及ADC图,测量肿瘤实质的ADC值。结果:ADC图像上,髓母细胞瘤呈低信号,肿瘤的ADC均值(0.76±0.15)×10^(-3)mm^2/s;星形细胞瘤高信号,肿瘤的ADC均值(1.66±0.15)×10^(-3)mm^2/s,差异具有统计学意义(P<0.05)。以肿瘤实质ADC<1.0×10^(-3)mm^2/s诊断髓母细胞瘤时,诊断特异度94.4%。结论:脑肿瘤实质ADC值对小儿髓母细胞瘤的诊断和鉴别诊断有重要价值。

Objective：To assess the value of apparent diffusion coefficient（ADC） in the diagnosis of pediatric medulloblastoma.Methods：33 pediatric patients with posterior fossa tumors,including 18 cases of medulloblastoma and 15 cases of astrocytoma,received diffusion-weighted MRI（DWI）.The DWI imagines and ADC map were retrospectively analyzed,and the ADC values in solid parts of tumor were calculated.Results：For patients with medulloblastomas,the tumors showed hypointense in 15 cases on ADC map,while slightly hypointense in 3 cases.And the average ADC value of tumor parenchymas was（0.76 ± 0.15） × 10-3mm2/s.On the contrary,all tumors showed hyperintense or slightly hyperintense in 15 patients with astrocytoma,and the average ADC value of tumor parenchymas was（1.66 ± 0.15）×10-3mm2/s,significantly higher than that of medulloblastoma（P〈0.05）.The specificity of diagnosis for medulloblastomas was 94.4% using a cut-off value of ADC 〈1.0×10-3mm2/s.Conclusion：Measurement of ADC value of cerebral tumor parenchyma is a simple and available method.It may play an important role in the differential diagnosis of pediatric medulloblastoma.