最小表观弥散系数对颅内少突胶质肿瘤分级及分型的价值

Oligodendroglial Tumors:Can Relative Apparent Diffusion Coefficient be Used in Prediction of Tumor Grade and Subtype

目的:评价最小表观弥散系数对颅内少突胶质肿瘤分级及分型的价值。材料和方法:24个病理证实为少突胶质肿瘤的病人(男性13人,女性11人,平均年龄45岁),包括4个Ⅲ级(间变型)少突星形细胞瘤(oligoastrocytomas,OA),6个Ⅲ级(间变型)少突胶质瘤(oligodendrogliomas,OD),2个Ⅱ级少突星形细胞瘤和12个Ⅱ级少突胶质瘤共4组。在肿瘤实质部分测定最小表观弥散系数(minimum apparent diffusion coeffi- cient,ADC_(min))值及对侧正常脑白质的ADC值,并计算其相对值(relative ADC_(min))。比较不同分级及病理分型组间平均rADC_(min)值并统计分析。结果:不同分型少突胶质肿瘤平均rADC_(min)分别为Ⅲ级OA0.95±0.05,Ⅲ级OD1.11±0.30,Ⅱ级OA1.69±0.59,Ⅱ级OD1.45±0.41,与肿瘤分级及恶性程度呈负相关(P=0.004)。rADC_(min)在两种级别少突胶质肿瘤中有显著性差异(P=0.014),进一步两两比较显示rADC_(min)在Ⅲ级OA与Ⅱ级OD,Ⅱ级OA之间均有显著性差异(P=0.027,P=0.029)。但Ⅲ级OD与Ⅱ级OD,Ⅱ级OA其平均rADC_(min)无显著性差异(P=0.067～0.081);当分界值rADC_(min)=1.03时鉴别Ⅱ级少突胶质肿瘤与Ⅲ级OA的敏感度为100%,特异度100%,但鉴别两种级别的少突胶质肿瘤敏感度仅60%,特异度100%。结论:rADC_(min)可以为少突胶质肿瘤分级提供有价值的信息,选择最适分界值rADC_(min)=1.03,可以鉴别Ⅲ级少突星形细胞瘤和Ⅱ级少突胶质肿瘤;但由于Ⅲ级OD其rADC_(min)与其余各组的交叉重叠,单独应用rADC_(min)鉴别两种级别肿瘤价值有限,rADC_(min)小于1.03可排除Ⅱ级少突胶质肿瘤。

Purpose： To retrospectively assess whether the relative apparent diffusion coefficient （rADC） can be used in prediction of tumor grade or subtype of oligodendroglial tumors. Materials and Methods： Findings from 24 patients （13 men, 11 women, mean age 45） with pathologically proved oligodendrogliomas that include 4 anaplastic oligoastrocytomas （OA grade Ⅲ ）, 6 anaplastic oligodendrogliomas （OD grade Ⅲ ）, 2 well - differentiated oligoastrocytomas （OA grade Ⅱ ） and 12 well - differentiated oligodendrogliomas （OD grade Ⅱ ）. The minimum apparent diffusion coefficient （ADCmim） value in tumor solid part of each tumor were measured, relative ADCmin was calculated by divided the ADC value at the normal appearing contralateral site into it. Mean values of rADCmin of different grades and subgroups were analyzed. Results： Mean rADCmin of different subgroups were 0.95 ± 0.05 for OA grade Ⅲ, 1.11 ± 0.30 for OD grade Ⅲ, 1.69 ± 0.59 for OA grade Ⅱ , 1.45 ± 0.41 for OD grade Ⅱ respectively. A significant negative correlation existed between rADCmin and different subgroups of oligodendroglial tumors（P = 0. 004）. While a significant difference was observed of rADCmin the two grades of thetumor （P = 0. 014）, whereas significant difference was only found between OA grade Ⅲ and the two low grade tumors（P = 0. 027, P = 0. 029 respectively） .A cutoff of rADCMin = 1.03 gave the sensitivity 100%, specificity 100% for differentiation low grade tumors from anaplastic oligoastrocytomas, but specificity 100%, sensitivity only 60% for differentiating the two grades of oligodendroglial tumors. Conclusion： The rADCmin can provide additional information about tumor grades, rADCmin has the potential benefit in differentiation high grade oligoastrocytomas from low grade oligodendroglial tumors with a cutoff of rAD- Cmin = 1.03, but overlapped with that of anaplastic oligodendrogliomas, rADCmin. alone has limited value for differentiation the two grades of oligodendroglial tumors. However a rADCmin smaller than 1.03 might not lead to the diagnosis of low grade oligodendroglial tumors.