扩散加权成像兴趣区选择在宫颈癌分化程度、淋巴结转移及脉管受侵中的对比研究

A comparative study of diffusion-weighted imaging region of interest selection in cervical cancer differentiation,lymph node metastasis and lymphovascular invasion

目的评价磁共振扩散加权成像兴趣区(ROI)不同测得的表观扩散系数(ADC)值在宫颈癌术前分化程度、淋巴结转移及脉管受侵中的应用价值。方法收集在我院经病理组织学证实为宫颈癌患者40例。所有患者均使用AVANTO1.5 T磁共振设备行常规检查及扩散加权成像(DWI)序列检查。按肿瘤分化程度分为高中分化及低分化组;根据淋巴结是否转移分为转移组与非转移组;根据脉管是否受侵分为阴性与阳性组。2名医师在宫颈癌DWI影像上采用3种ROI法(最大面积ROI、容积ROI、小ROI)独立测量病灶的ADC值。比较各组间指标的差异;运用受试者工作特征(ROC)曲线对差异有统计学意义的参数进行分析,获得相应的曲线下面积(AUC)、最佳临界值和诊断性能。结果3种ROI法测得不同ADC值的一致性均较好,其中容积ROI法测得的ADC值的一致性最好。高中分化组、低分化宫颈癌组最大面积ROI法和容积ROI法的平均ADC值差异有统计学意义(P<0.01),容积ROI法平均ADC值区分高中分化及低分化宫颈癌AUC值最大,为0.854,最佳临界值为0.602×10^-3 mm^2/s。淋巴结非转移组、转移组容积ROI法测得的平均ADC值及小ROI法大-小值差异有统计学意义(P<0.05),容积ROI法平均ADC值的AUC值最大,为0.788,最佳临界值为0.594×10^-3 mm^2/s。有、无脉管癌栓组最大面积ROI法测得的最小值,容积ROI法测得的平均ADC值、最小值,小ROI法测得的平均ADC值、最小值差异有统计学意义(P<0.05),容积ROI法的最小值所得AUC值最大,为0.910,最佳临界值为0.439×10^-3 mm^2/s。结论3种ROI法中容积ROI法测得宫颈癌的ADC值重复性最好。容积ROI法的平均ADC值对宫颈癌分化程度、淋巴结转移预测价值较高,容积ROI法的最小ADC值对脉管受累预测价值较高。

Objective To evaluate the values of different apparent diffusion coefficient(ADC)of regional of interest(ROI)selection for magnetic resonance diffusion-weighted imaging(DWI)in identifying differentiation degree,lymph nodes metastasis and lymphovascular invasion in preoperative cervical cancer.Methods Forty patients with cervical cancer confirmed by pathological examination in our hospital were enrolled.All patients underwent MRI routine scanning sequence and DWI sequence using AVANTO 1.5 T magnetic resonance.According to the pathological stage after operation,the degree of tumor differentiation,patients were divided into two groups(high grade and low grade groups).According to the lymph node metastasis patients were divided into two groups(metastasis group and non-metastasis group).According to the lymphovasvular invasion patients were divided into two groups(positive group and negative group).Three methods of ROI measurements(area ROI,volume ROI and small ROIs)were used on DWI images of cervical caner cancer by two physicians with different seniority independently measuring apparent diffusion coefficient(ADC)value of lesions.Differences between groups were analyzed.The parameters with significant differences were analyzed by receiver operating characteristic(ROC)curve and obtaining the area under the curve(AUC),corresponding optimum cutoff value,and diagnostic performance.Results All the ADC values obtained by three methods of ROI measurements had good repeatability,and the ADC values of volume ROI were the best.There were significant differences in mean value of area ROI and volume ROI between highmiddle grade and low grade cervical cancer(P<0.01).The ROC curve was used to identify high-middle grade and low grade using the ROI volume measurement with the biggest AUC:0.854,the optimal cutoff value was 0.602×10^-3 mm^2/s.There were significant differences in mean ADC of volume ROI and the max ADC-minimum ADC of small ROI lymph node metastasis between metastasis group and non-metastasis group(P<0.05).The ROC curve was used to identify high-middle grade and low grade using the ROI volume measurement with the biggest AUC:0.788,the optimal cutoff value was 0.594×10^-3 mm^2/s.The minimum ADC of area ROI,the mean ADC and the minimum ADC of the volume ROI,the mean ADC and the minimum ADC of the small ROC were significantly different in lymphvascular invasion(P<0.05).The ROC curve was used to identify lymphvascular invasion using the ROI volume measurement with the biggest AUC:0.910,the optimal cutoff value was 0.439×10^-3 mm^2/s.Conclusion The ADC measured by volume ROI method is the best repeatability among the three ROI methods.The mean ADC of the volume ROI method and the minimum ADC of the volume ROI method are the best predictive value in the differentiation degree,lymph nodes metastasis and lymphovascular invasion of cervical cancer in turn.