小视野弥散加权成像在前列腺癌诊断中的应用价值

Reduced field-of-view diffusion weighted imaging in diagnosis of prostate cancer

目的随着技术的提高和方案的完善,小视野弥散加权成像(reduced field of view diffusion weighted imaging,r FOV DWI)提供了更可靠的成像质量。文中通过与常规弥散加权成像(diffusion weighted imaging,DWI)对比,探讨r FOV DWI在前列腺癌诊断中的应用价值。方法回顾性分析2014年8月至2015年9月期间在南京军区南京总医院就诊的58例行3.0T MRI r FOV DWI和常规DWI检查,并随后接受穿刺活检证实的前列腺疾病患者。其中确诊为前列腺癌及前列腺增生的患者分别为31例和27例。由2位影像科医师在未知任何临床及MRI序列信息的情况下,针对全部患者的DWI图像几何变形、肿瘤患者的DWI图像(b=1000)以及ADC图像的病灶显示清晰程度3个方面按4个等级(1~4分)进行独立评分。r FOV DWI和常规DWI均分别采用400、1000及0 s/mm^2共3个b值。采用双指数模型软件处理获得ADC值、慢弥散系数(D值)以及快速弥散所占的容积分数(f值)的参数化图像。分别测量2个序列前列腺癌患者肿瘤区域以及良性前列腺增生患者正常外周带的ADC、D以及f值。以闭孔内肌作对照,分别计算其比值r ADC、r D及rf值。对2个序列不同参数诊断前列腺癌的效能进行ROC曲线分析。结果与常规DWI序列相比,r FOV DWI序列的图像变形更小,病灶显示清晰程度更高(P<0.01),且r FOV DWI序列中前列腺癌患者肿瘤区域的ADC及D值更低,分别为(0.728±0.094 vs 0.789±0.116)和(0.622±0.077 vs0.651±0.099),差异有统计学意义(P<0.05);而两者的f值比较,差异无统计学意义(P=0.932)。r FOV DWI和常规DWI序列f值ROC曲线下面积比较,差异无统计学意义(0.853 vs 0.767,P=0.283)。结论 r FOV DWI序列可有效改善图像质量,对前列腺癌的临床诊断具有重要价值。

Objective With the improvement of technology and strategy,reduced field- of-view diffusion weighted imaging（ r FOV DWI） has provided more robust imaging. This article was intended to compare the clinical utility between r FOV DWI and conventional DWI in the diagnosis of prostate cancer. Methods Retrospective analysis was made on 58 prostate cancer patients undergoing verification of biopsy or surgery after 3. 0 T MRI r FOV DWI and regular DWI examinations in Nanjing General Hospital of Nanjing Military Command from August 2014 to September 2015,among whom prostate cancer and benign prostatic hyperplasia were 31 cases and 27 cases respectively. Independent grading was made by 2 radiologists who were unaware of any clinical data and sequences in the aspects of distortion on DW images,lesion conspicuity on DWI（ b =1000） and ADC images according to a 4-point Likert scale. r FOV and conventional DWI sequences were acquired using b = 400,1000,0s / mm^2. The IVIM double exponential model software was applied to generate ACD value,slow dispersive coefficient（ D value） and parameterized image of volume fraction of fast dispersion（ f value）. Sequence analysis was made in suspected peripheral tumor regions of prostate cancer patients and and healthy peripheral zones of patients with benign prostatic hyperplasia respectively to get ACD,D and f values. The ratio values r ADC,r D and rf were attained compared with obturator internus. ROC analysis was made on the efficacy of different parameters of two sequences in prostate cancer. Results Image qualities of r FOV DWI were rated superior to conventional DWI（ P 〈0. 001,Wilcoxon Signed-Rank Test）. Compared with conventional DWI,ADC value（ 0. 728 ± 0. 094 vs 0. 789 ± 0. 116,P 〈0. 05） and D value（ 0. 622 ± 0. 077 vs 0. 651 ± 0. 099,P〈 0. 05） of peripheral tumor regions in r FOV DWI were lower and the difference was statistically significant,whereas no significant difference was found in f value（ P = 0. 932）. No difference was found in area under ROC curve of f value between r FOV DWI and traditional DWI（ 0. 853 vs 0. 767,P = 0. 283）. Conclusion The r FOV DWI sequence yielded can efficiently improve image quality,which is of important value to the clinical diagnosis of prostate cancer.