磁共振扩散加权成像在儿童髓母细胞瘤诊断中的价值

Value of diffusion weighted MR imaging in the diagnosis of medulloblastoma in children

目的:探讨扩散加权成像(DWI)对儿童髓母细胞瘤的诊断价值。方法:回顾性分析我院经病理证实的66例儿童髓母细胞瘤患者的MRI特点,重点分析肿瘤实质的ADC值,从同时期儿童后颅窝室管膜瘤病例中选取20例作为对照。结果:66例髓母细胞瘤中50例位于后颅窝中线部(小脑蚓部),7例位于后颅窝非中线部(主要位于小脑半球),9例同时累及后颅窝中线部及非中线部,病变边界较清,周围均可见不同程度水肿;肿瘤实质呈等或稍长T1稍长T2信号,肿瘤呈不同程度的不均匀强化。DWI(b=1000s/mm2)图像上60例肿瘤实性部分呈高信号,6例肿瘤实性部分呈等信号。影像报告第一诊断准确率为68%(45/66)。髓母细胞瘤组及室管膜瘤组的肿瘤实质ADC值分别为(0.6815±0.1613)×10-3 mm2/s、(1.0068±0.1736)×10-3 mm2/s,差异有统计学意义(P<0.001)。受试者工作特征(ROC)曲线分析显示肿瘤实质ADC值诊断髓母细胞瘤的准确度较高(曲线下面积为0.942),最佳诊断分界点为0.7817×10-3 mm2/s。结论:DWI图像及肿瘤实质ADC值可以提高儿童髓母细胞瘤的影像诊断准确率,降低误诊率,同时肿瘤实质ADC值也可为计算机辅助诊断的开展提供依据。

Objective:To assess the value of diffusion weighted imaging(DWI)in the diagnosis of medulloblastoma in children.Methods:MRI characteristics of 66 pediatric patients with pathology proved medulloblastoma in our hospital were retrospectively analyzed.Mainly,the ADC value of tumor parenchyma was analyzed.20 pediatric patients with posterior cranial fossa ependymoma in the same period were chosen as control.Results:Of the 66 patients with melulloblastoma,the location of lesion was as follows:at the midline of posterior cranial fossa(the cerebellar vermis)(50 patients),off the midline of posterior cranial fossa,mainly in the cerebellar hemisphere(7 patients),the other 9 patients had the lesion located both at and off the midline.Most of the lesions were with clear boundary and with various degree of peritumoral edema.Tumor parenchyma showed iso-or slightly long T 1 signal on T 1WI and slightly long T 2 signal on T 2WI,with different degrees of heterogeneous enhancement.On DWI(b=1000/mm 2)tumor parenchyma showed hyperintensity in 60 cases,and iso-intensity in the other 6 cases.The diagnostic accuracy of first imaging diagnostic report was 68%(44/66 patients).The ADC value of tumor parenchyma in medulloblastoma and ependymoma group was(0.6815±0.1613)×10-3 mm 2/s and(1.0068±0.1736)×10-3 mm 2/s respectively,with statistically significant difference(P<0.001).ROC curve analysis showed that the diagnostic accuracy of using ADC value of tumor parenchyma for the diagnosis of medulloblastoma was high(AUC,0.942).The optimal cut-off value was 0.7817×10-3 mm 2/s.Conclusion:DWI and ADC value of tumor parenchyma can improve preoperative diagnosis accuracy of medllublastoma in children,the misdiagnosis rate could be reduced.ADC value of tumor parenchyma also provides the basis for computer aided diagnosis.