3.0T弥散加权成像表观弥散系数值对肾盂癌侵袭性的评价价值

Apparent diffusion coefficient value of 3.0T MR diffusion-weighted imaging in assessing invasiveness of renal pelvic carcinoma

目的探讨3.0T磁共振弥散加权成像(diffusion-weighted imaging,DWI)对肾盂癌的诊断价值及其表观弥散系数(apparent diffusion coefficient,ADC)值与病理分期分级的关系。方法回顾性分析33例肾盂癌患者的临床资料。所有患者均行常规磁共振扫描及DWI检查(b值=0和b值=800s/mm^2),将磁共振DWI诊断结果与病理结果进行对照,计算DWI诊断肾盂癌的敏感性、特异性、准确率、阳性预测值、阴性预测值。分析并记录病灶的DWI信号特点,对每个病灶选择3个感兴趣区(region of interest,ROI):小ROI、大ROI及最小ADC值。比较不同性别间、不同部位肾盂癌间、肾盂癌与正常肾实质间、3组ROI间、不同病理分级和不同临床分期间的ADC值的差异。采用免疫组织化学染色方法检测Ki-67在肾盂癌组织中的表达,分析Ki-67表达与ADC值的关系。结果当b值=800s/mm^2时,利用DWI诊断肾盂癌的敏感性为90.9%、特异性91.4%、准确率91.2%、阳性预测值90.9%、阴性预测值91.4%。ADC值在不同性别、不同部位肾盂癌间差异无统计学意义(P>0.05),在肾盂癌与正常肾实质间差异有统计学意义(P<0.05),在3组ROI间差异无统计学意义(P>0.05)。低级别(G_1~G_2级)肾盂癌的ADC值较高级别(G_3级)高,局限于肾盂(Ta^T_2期)的ADC值较有局部侵犯(T_3期)高,差异均有统计学意义(P<0.01,P<0.05)。Ki-67表达与肿瘤的病理分级、分期有关,ADC值与Ki-67的表达量呈负相关(r=-0.88,P<0.01)。结论 ROI的大小对于尿路上皮癌的鉴别意义可能不大;在不使用造影剂的情况下,DWI有利于术前评估肾盂癌的组织学分级及分期。

Objective To investigate the value of 3.0T MR diffusion-weighted imaging（DWI）in diagnosing the renal pelvic cancer and the association of apparent diffusion coefficient（ADC）value with the histological grade and clinical stage of cancer.Methods The clinical data of 33 patients with renal pelvic carcinoma were retrospectively analyzed.Routine MRI and DWI with b-values of 0and 800s/mm^2 were performed,and the examination results were compared with the corresponding pathological results.We then calculated the sensitivity,specificity,accuracy,positive and negative predictive values of DWI.The DWI signal characteristics of lesions were recorded and analyzed,and three regions of interest（ROIs）,large and small ROIs and minimum ADC（minADC）value,were selected for each lesion.The differences of ADC values between different genders,locations,cancer tissue and normal renal parenchyma,among three ROIs,among different pathological grades,among different clinical stages were compared and analyzed.Immunohistochemical staining was used to detect the expression of Ki-67 in renal pelvic cancer tissues,and the relationship between ADC value and Ki-67 expression was also analyzed.Results The results of DWI with 800s/mm^2 b-value showed that the sensitivity,specificity,accurate rate,positive and negative predictive value for renal pelvic carcinoma were 90.9%,91.4%,91.2%,90.9% and 91.4%,respectively.The ADC values were significantly different between normal renal parenchyma and renal pelvic carcinoma tissues（P〈0.05）,and they were not significantly different between different genders,locations or among small ROI,big ROI and the minADC values.The ADC value of low grade（G_1-G_2）tumors was significantly higher than that of high grade（G_3）ones（P〈0.01）.The ADC value of cancer cells confined to the renal pelvis（Ta-T_2）was higher than that with local invasion（T_3）（P〈0.05）.Ki-67 expression was found associated with the pathological grades and tumor stages of pelvic carcinoma,and there was a negative correlation between ADC value and Ki-67expression（r=-0.88,P〈0.01）.Conclusion Our findings suggest that the size of ROI may be of little value in diagnosis of urothelial carcinoma,and DWI may contribute to the preoperative assessment of histological grade and clinical stages of renal pelvic carcinoma.