多参数3.0 T MR:鉴别低级别与高级别及T_1与T_2期膀胱尿路上皮癌

Multi-parametric 3.0 T MRI for differentiating low-versus high-grade and category T_1 versus T_2 bladder urothelial carcinoma

目的探讨术前无创性准确鉴别高、低级别以及T1、T2期膀胱尿路上皮癌的多参数MR理想模式。方法 39例因怀疑膀胱癌且未行任何治疗的患者于我院行膀胱MR平扫、扩散加权成像(DW-MRI)及动态增强(DCE-MRI)检查,所有患者于1周内接受了经尿道膀胱肿瘤电切术或膀胱癌根治术,术后标本送病检。所得MR图像分成3种组合:T2WI加DWI、T2WI加DCE-MRI、T2WI加DWI加DCE-MRI。两位阅片者在不知病理结果的前提下分别独立阅片;每组图像的阅片间隔时间为2周。绘制ROC曲线,采用Bonferroni检验分别比较三种影像组合判断肿瘤有无侵犯膀胱肌层的诊断效能。以手术病理为金标准,分析肿瘤ADC值与瘤灶病理级别的关系。结果共计49个瘤灶(T1期36个,T2期13个)纳入研究,低级别肿瘤(11个)的ADC值(1.141±0.164)×10-3 mm2/s明显高于高级别肿瘤(20个)的ADC值(0.766±0.091)×10-3 mm2/s,差异具有明显统计学意义(P<0.05)。参照T2WI加DWI及T2WI加DWI加DCE-MRI组合阅片时,两位阅片者均无出现将T1期肿瘤判定为肿瘤侵犯肌层(误认为T2期),当参照T2WI加DCE-MRI组合阅片时,两位阅片者将T1期肿瘤过高分期(即误认为T2期)的病灶数分别为13和15个。ADC值为0.899×10-3 mm2/s时,鉴别两者的敏感性及特异性最好,分别为100%、95%。结论在无创性准确鉴别膀胱尿路上皮癌的临床分期和全瘤病理分级时,多参数MR T2WI加DW-MRI加DCE-MRI是最佳组合。当ADC值为0.899×10-3mm2/s时,鉴别高级别与低级别膀胱癌的敏感性及特异性最好,分别为100%、95%。

Objective To determine an optimal multi-parametric MRI protocol for characterizing tumors of low versus high grade and differentiating tumors as T1 versus T2 in preoperative staging of bladder urothelial carcinoma..Methods 39 patients underwent MRI within 1 week before surgery. Three image sets of T2-weighted plus diffusion-weighted MRI （DWI）, T2-weighted plus dynamic contrast-enhanced MRI. （DCE-MRI）,.and T2-weighted plus DCE-MRI plus DWI were independently interpreted by two readers at 2-week intervals. ROC curves were plotted for both readers to compare the diagnostic efficacy of the three sets for detrusor muscle invasion for each reader..The areas under the ROC curves were compared using the Bonferroni test..The apparent diffusion coefficient. （ADC）.values were correlated with histopathologic grade..Results A total of 49 category T1 and T2 lesions were analyzed. The average ADC of 11 low-grade tumors （1.141±0.164）×10^-3 mm^2/s was significantly （P〈0.05） higher than that of 20 high-grade malignancy. （0.766 ±0.091） ×10-3 mm2/s..No T1 tumors were read as having muscle invasion. （category T2）.on the T2-weighted plus DWI image sets or the T2-weighted plus DWI plus DCE-MRI image sets..Using the T2-weighted plus DCE-MRI image sets,.both readers overstaged 13/36 and 15/36 T1 tumors as T2,.respectively..With the cutoff ADC value of 0.899×10^-3 mm^2/s,the sensitivity and specificity for differentiating high- and low-grade bladder urothelial carcinoma were 100% and 95%,.respectively. Conclusion Multi-parametric MRI with T2-weighted plus DWI plus DCE technique is the optimal protocol for preoperative staging of bladder urothelial carcinoma..The ADC of low-grade tumors is significantly higher than that of high-grade malignancy with 100%sensitivity and 95% specificity at a cutoff ADC value of 0.899× 10^-3 mm^2/s.