不典型髓母细胞瘤MRI及ADC值在诊断中的价值

Value of MRI Features and ADC Value in Diagnosis of Atypical Medulloblastoma

目的:通过探讨髓母细胞瘤的MRI征象及表观扩散系数(ADC)值在髓母细胞瘤诊断中的价值,重点提高不典型髓母细胞瘤的影像学诊断水平。方法:回顾性分析41例经手术和病理证实的髓母细胞瘤,根据MR增强表现分为典型和不典型两组,其中典型21例,不典型20例,对肿瘤发生部位、病灶大小、边缘、MRI信号特点、囊变、出血、钙化、有无转移以及DWI等进行比较,并对肿瘤实质部分的ADC值进行统计学分析。结果:41例髓母细胞瘤中,7例位于小脑蚓部,16例位于第四脑室,17例位于小脑半球,1例位于左侧桥小脑角区,病灶周围水肿为无~中度,22例有不同程度幕上脑积水,DWI信号高者8例,稍高者32例,低者1例,ADC值信号高者21例,低者20例,病灶内微囊变10例,中囊变者3例,大囊变1例,21例可见瘤周囊变,增强扫描轻中度云絮状强化18例,明显强化21例,2例强化不明显。根据肿瘤的强化程度,典型组和不典型组ADC值分别为(0.678±0.078)×10^(-3)mm^2/s和(0.745±0.091)×10^(-3)mm^2/s,其差异无统计学意义,总体ADC值为(0.711±0.084)×10^(-3)mm^2/s。结论:典型与不典型髓母细胞瘤在MRI上具有一定的影像学特征,ADC值对其诊断与鉴别诊断提供帮助。

Purpose： Through exploring the value of MRI features and apparent diffusion coefficient （ADC） value in the diagnosis of medulloblastoma, to improve the imaging diagnosis level of atypical medulloblastoma. Methods： We retrospectively analyzed 41 cases of medulloblastoma, which were proved by surgery and pathology results. According to the features on MR enhancement scan, the cases were divided into typical group （21 cases） and atypical group （20 cases）. The tumor location, lesion size, edge, MR signal characteristic, cystic degeneration, hemorrhage, calcification, metastasis and DWI signal intensity, and the ADC value of the tumor parenchyma were analyzed. Results： Of 41 cases of medulloblastoma, 7 cases occurred in the cerebellum vermis, 16 cases in the fourth ventricle, 17 in the cerebellar hemisphere, 1 in the left cerebellopontine angle. There were no, mild or moderate edema around the lesions. Twenty-two cases were with hydrocephalus in different grades. On DWI： high intensity signal was shown in 8 cases; moderate intensity signal in 32 cases; low intensity signal in 1 case. On ADC maps： high intensity signal was shown in 21 cases; low signal in 20 cases. Micro cystic degeneration was shown in 10 cases; moderate in 3 cases; and macro in 1 case. Cystic changes around the tumor was shown in 21 cases. On enhancement scan： 18 cases were mild to moderate enhanced, 21 cases were obviously enhanced, while 2 cases were with no obvious enhancement. According to the degree of enhancement of the tumors, ADC values of typical group and atypical group were （0.678±0.078）×10^-3mm^2/s and（0.745±0.0919）×10^-3mm^2/s, respectively, which were with no statistical significant difference. The overall mean ADC value was （0.711±0.084）×10^-3mm^2/s. Conclusion： Typical and atypical meduUoblastomas have different imaging characteristics on MRI. ADC values are valuable in diagnosing typical and atypical medulloblastoma, which are helpful for diagnosis and differential diagnosis.