冠状面小视野高分辨DWI在输尿管狭窄评估中的应用

Comparison of coronal reduced field-of-view diffusion-weighted imaging(DWI)and conventional axial DWI in the assessment of ureteral stenosis

目的:探究冠状面小视野(FOV)高分辨DWI(MicroV DWI)对于输尿管狭窄影像评估的应用价值。方法:本研究前瞻性连续入组51例于3.0T行全泌尿系磁共振检查的输尿管狭窄伴积水患者。所有患者具备两组DWI图像:①常规全泌尿系全FOV轴面单激发平面回波成像(SS-EPI)DWI(C-DWI);②输尿管狭窄段冠状面小FOV高分辨DWI(M-DWI)。两位读片者独立盲法定性评价C-DWI和M-DWI的图像质量,包括锐利度、变形、伪影及病变显示。对于输尿管狭窄段,定性分析狭窄处输尿管病变DWI图像信号增高程度,并定量测量两组ADC图中输尿管狭窄处的平均ADC值。两位读片者在两组图像上(组1:T_(2)WI+C-DWI;组2:T_(2)WI+C-DWI+M-DWI)主观判断输尿管狭窄的良恶性。输尿管狭窄的良恶性最终通过临床、实验室检查、内镜及手术获取。结果:两位读片主观评价一致性好(Kappa=0.711~0.867)。M-DWI图像锐利度、变形、伪影及病变显示均较C-DWI主观评分显著提高(P<0.05)。对于狭窄段定性分析在两组DWI图像上恶性狭窄大部分表现为信号明显增高,良性狭窄大部分表现为信号轻度或无增高,两组DWI图像上对于狭窄段信号增高程度的判断一致性好(读片者1:Kappa=0.771;读片者2:Kappa=0.670)。对于狭窄段ADC值的定量分析M-DWI的ADC值较C-DWI降低(P<0.001),但两组ADC值一致性好(ICC=0.916),两组ADC图上恶性狭窄ADC值均显著低于良性狭窄(P<0.001)。对于输尿管狭窄段良恶性判断,组2(T_(2)WI+C-DWI+M-DWI)较组1(T_(2)WI+C-DWI)对于输尿管恶性狭窄的诊断效能提高(组1 AUC=0.863,组2 AUC=0.962;P=0.021)。结论:冠状面小FOV高分辨M-DWI较常规全FOV SS-EPI C-DWI提高图像质量及输尿管狭窄的病变显示能力。在常规序列中额外加扫输尿管狭窄段小FOV高分辨DWI可提高输尿管良恶性狭窄的鉴别诊断能力。

Objective:To investigate the value of coronal reduced field-of-view(FOV)high-resolution DWI(MicroV DWI)for the differentiation of benign and malignant ureteral stenosis.Methods:This prospective study enrolled 51 consecutive patients with ureteral stenosis and hydronephrosis who underwent urinary MRI examination at 3.0T.All patients have two sets of DWI images:(1)conventional axial full FOV(single shot planar echo imaging(SS-EPI))DWI(C-DWI);(2)coronal reduced FOV DWI(MicroV DWI,M-DWI)at ureteral stenosis.Two readers independently evaluated the image quality of C-DWI and M-DWI,including sharpness,distortion,artifacts and lesion conspicuity.Two readers qualitatively analyzed the signal intensity of two DWI images.One reader quantitatively measured the average ADC values at the ureteral stenosis.Two readers defined benign or malignant of the ureteral stenosis subjectively on two sets of images(set 1:T_(2)WI+C-DWI;set 2:T_(2)WI+C-DWI+M-DWI).The reference standards were obtained by combining clinical data,laboratory examination,endoscopy,or surgery.Results:Inter-reader agreement was good(Kappa=0.711~0.867).Image quality of M-DWI was significantly improved compared with C-DWI(P<0.05).For qualitative analysis of signal intensity on DWI,two DWI images had good consistency(reader 1:Kappa=0.771;reader 2:Kappa=0.670).The ADC value of M-DWI was lower than that of C-DWI(P<0.001),and ADC value measurements were in good consistency(ICC=0.916).The ADC value of malignant stenosis were significantly lower than that of benign stenosis for both DWI(P<0.001).For differentiation of benign and malignant ureteral stenosis,set 2(T_(2)WI+C-DWI+M-DWI)showed better diagnostic efficiency than set 1(T_(2)WI+C-DWI)(AUC of set 1=0.863,AUC of set 2=0.962;P=0.021).Conclusion:Compared with the conventional full FOV SS-EPI DWI,the coronal high-resolution reduced-FOV M-DWI may provide higher image quality and improve ureteral stenosis visualization.Adding M-DWI to routine sequence may improve the diagnostic efficiency in the differential diagnosis of benign and malignant ureteral stenosis.