髓母细胞瘤的CT和MRI诊断

CT and MRI Diagnosis of Medulloblastomas

目的:提高髓母细胞瘤CT、MRI诊断的正确性.材料和方法:经病理证实的髓母细胞瘤50例,34例作CT检查,30例作MRI检查,其中30例同时行CT和MRI检查.结果:发病年龄小于20岁者占78%(39/50),发生于小脑蚓部者占88%(44/50).其中CT平扫为略高密度者占53%(18/34),混合密度者占44%(15/34).CT增强后病灶呈均匀强化者占50%(17/34),不均匀强化者占38%(13/34),环状强化者占12%(4/34).MRIT_1WI病灶呈低信号者占73%(22/30),混合信号者占27%(8/30).T2WI呈高信号者占73%(22/30),混合信号者占23%(7/30).MRI增强后病灶呈均匀强化者占72%(13/18),不均匀强化者占22%(4/18),有5%(1/18)病灶显示环状强化.病灶可见囊变、钙化、出血、瘤周水肿及脑积水征象.CT对髓母细胞瘤检出率、定位、定性诊断正确率分别为97%、90%、83%,而MRI则分别为100%、96%、90%,二者统计学处理有显著性差异(X^2检验:P<0.05).结论:髓母细胞瘤的CT和MRI表现具有特征性.

Purpose: For promoting the CT and MRI diagnostic accuracy of medulloblastomas. Materialsand Methods: 50 surgical pathologic proven patients, 34 cases were evaluated with CT, 30cases with MRI and 30 cases with both CT and MRI. Results: 39 cases(78% ) were lessthan 20 years old, 44 cases(88%) were located at the mid and inferior vermis. On CT plainscans, the tumors were predominantly slightly hypodensity(50% ) and inhomogeneous density(44%), on post - contrast CT image, the tumors were enhanced homogeneously (73 %). MRIfindings were: medulloblastomas generally appeared hypointense(73%) on T1WI and hyperin-tense on T2WI(73%), on post - contrast scans, MR image showed marked homogeneous en-hancement (73%). Other features, included cystic component, calcification, hemorrhage, peritu-moral edema, hydrocephalus. The sensitivity(detection rate), localization, and property determi-nation accuracies of CT and MRI on medulloblastoma were 97%, 90%, 83% respectively forthe former and 100%, 96%, 90% respectively for the latter. Conclusion: The CT and MRI areefficient and accurate methods for detecting medulloblastomas. The differential diagnosis ofmedulloblastoma includes astrocytoma, ependymoma,hemangioblastoma.