表观扩散系数在诊断小脑原发肿瘤的应用价值

Value of apparent diffusion coefficient in diagnosing primary cerebellar tumor

目的:表观扩散系数(Apparent diffusion coefficient,ADC)能反映肿瘤细胞的微观状态,本文探讨其对小脑原发肿瘤的诊断价值。方法:对44例经手术病理证实的小脑原发肿瘤的MRI资料进行回顾性分析,包括11例血管母细胞瘤,12例毛细胞型星形细胞瘤,11例髓母细胞瘤,6例室管膜瘤,2例淋巴瘤,2例脉络丛乳头状瘤。全部病例均行MRI常规扫描,弥散加权成像(Diffusion-weighted imaging,DWI)及ADC值测量,对前4种肿瘤的绝对ADC值、相对ADC值在Stata 9.0上进行单因素方差分析及Bonferronit t检验。结果:不同肿瘤间的绝对ADC值及相对ADC值均有差异(P<0.001),血管母细胞瘤的ADC值[(1.97±0.214)×10-3mm2/s)]要明显高于毛细胞型星形细胞瘤[(1.643±0.223)×10-3mm2/s](P=0.001),髓母细胞瘤的ADC值[(0.698±0.124)×10-3mm2/s]明显低于室管膜瘤[(1.062±0.148)×10-3mm2/s](P=0.003),毛细胞型星形细胞瘤则明显高于室管膜瘤(P<0.001);脉络丛乳头状瘤亦有较高的ADC值,而淋巴瘤有较低的ADC值。在髓母细胞瘤、室管膜瘤、毛细胞型星形细胞瘤及血管母细胞瘤这4种肿瘤中,取<0.8×10-3mm2/s、(0.9～1.2)×10-3mm2/s、(1.3～1.7)×10-3mm2/s、>2.1×10-3mm2/s分别作为上述肿瘤的ADC值的界值时,可获得100%的特异性。结论:ADC值是诊断小脑肿瘤的简便而实用的工具。

Objective： Apparent diffusion coefficient （ADC） can reflect the micro status of tumor cell, this study is to discuss the value of ADC in primary cerebellar tumor. Methods- Forty-four patients with histologically proved primary cerebellar tumor were reviewed retrospectively. There were 11 heamangioblastoma, 12 pilocytic astrocytomas, 11 medulloblastomas, 6 ependymomas, 2 lymphoma and 2 choroid plexus papillomas. All patients were examined by conventional MRI; DWI; and ADC value obtained from ADC maps. Absolute ADC values and ADC ratios of heamangioblastoma, pilocytic astrocytomas, medulloblastomas, ependymomas were calculated and compared by using one-way analysis of variance and Bonferronit t test. Results： The differences of both absolute ADC value and ADC ratio were significant among these 4 tumor types. ADC values were significantly higher in heamangioblastomas[（1.97±0.214）×10^-3mm^2/s] than in pilocytic astrocytomas[（1.643±0.223）×10^-3mm^2/s] （P=0.001）, ADC values in medulloblastomas [（0.698±.124）×10^-3mm^2/s] were significantly lower than in ependymomas [（1.062± 0.148）×10^-3mm^2/s]（P=0.003）. And pilocytic astrocytomas demonstrated significantly higher ADC values than ependymomas （P〈 0.001）. Our cut off values of 〈0.8×10-amm2/s, （0.9-1.2）×10^-3mm^2/s, （1.3-1.7）×10^-3mm^2/s, 〉2.1×10^-3mm^2/s for medulloblastomas, ependymomas, pilocytic astrocytomas and heamangioblastomas respectively were 100% specific. Conclusion： ADC value is an easy and useful tool in diagnosing primary cerebellar tumor.