最小表观弥散系数值在弥散加权成像诊断四脑室原发性肿瘤中的应用价值

摘要

目的：研究四脑室常见原发性肿瘤常规磁共振成像(MRI)表现、弥散加权成像(DWI)最小表观弥散系数(ADC)间的差异以及鉴别诊断价值。方法：选取100例四脑室原发肿瘤患者，对其行MRI检查，记录肿瘤实质平均最小ADC值；对3种不同形态细胞瘤的平均最小ADC值行方差检验，两两进行LSD-t检验，计算其结果；DWI受限高信号以平均最小ADC值0.875×10-3 mm2/s作为阈值，比较其对四脑室髓母细胞瘤的特异度、灵敏度、阴性预测值和阳性预测值。结果：在100例患者中有43例髓母细胞瘤患者表现为小脑半球受压后移或小脑扁桃体下疝，DWI上肿瘤显示受限扩散高信号，瘤体ADC值最小为(0.43±0.15)×10-3 mm2/s；33例星形细胞瘤患者表现为显著占位效应，ADC值最小为(1.58±0.58)×10-3 mm2/s；24例室管膜瘤患者表现为MRI典型“融蜡”样变，瘤体ADC值最小为(0.93±0.18)×10-3 mm2/s；3种不同形态细胞瘤的平均最小ADC值检验计算，差异有统计学意义(F=21.985，P=0.001)；与病理学结果比较，其对四脑室髓母细胞瘤的特异度为98.5%，灵敏度为97.3%，阴性预测值为98.5%，阳性预测值为100%，将该结果与组织学检查结果行抑制性检验，Kappa值为0.912。结论：将ADC及DWI与常规MRI联合用以诊断四脑室常见原发肿瘤，具有较高的特异度、灵敏度、阴性预测值和阳性预测值，其诊断效果明显，应用价值大。%Objective:To analyze the differences and common differential diagnostic value on the fourth ventricle magic resonance imaging (MRI) findings of primary tumors, diffusion-weighted imaging (DWI) and minimum apparent diffusion coefficient (ADC).Methods:A total 100 cases with the fourth ventricle of the primary tumor who were given MRI examination, were selected from March 2011 to April 2012 in our hospital, recording an average minimum ADC value of tumor parenchyma.Results: 43 cases of medulloblastoma showed cerebellar hemisphere pressed shift or tonsillar herniation and restricted diffusion on DWI tumors showed high signal tumor. The minimum ADC value was (0.43±0.15)×10-3mm2/s. 33 cases of astrocytomas showed significant mass effect and the minimum ADC value was (1.58±0.58)×10-3mm2/s. 24 cases of ependymoma MRI showed typical “melting wa×” degeneration and tumor minimum ADC value was(0.93±0.18)×10-3mm2/s. The minimum ADC value of the three different forms of tumor cell lines was calculated by variance test and twenty-two row-LSD-t test, and the results were statistically significant difference (F=21.985,P=0.001). DWI high signal is limited to an average minimum ADC value of 0.875×10-3mm2/s as a threshold value. Compared with the pathology, the specificity of the fourth ventricle medulloblastoma was 98.5%, the sensitivity was 97.3%, the negative predictive value was 98.5%, and a positive predictive value was 100%. The suppression test was carried out between all the results above and the results of histological findings and Kappa value was 0.912.Conclusion: The primary tumor of the fourth ventricle was diagnosed with the ADC, DWI and conventional MRI, which showed that the specificity, sensitivity, negative predictive value and positive predictive value were high. It had obvious diagnostic effect and great value.