目的 探讨MRI直肠磁敏感伪影对于前列腺癌主观评价和深度学习计算机辅助诊断(deep learning-based computer aided diagnosis,DL-CAD)的影响.材料与方法 回顾性分析685例行双参数MRI检查患者的影像资料,所有病例均通过穿刺活检或手术切片获得病理结果,由三组不同年资放射科阅片医师(阅片者1～6)分别依据前列腺成像报告和数据系统(prostate imaging report and data system,PI-RADS)v2.1版对前列腺MRI上的可疑病灶进行独立评审.另外两位阅片医师(阅片者甲、乙)对MRI上是否存在直肠伪影以及伪影程度进行评分.构建基于前列腺MRI的DL-CAD诊断模型评估直肠伪影对于深度学习诊断模型的影响.采用加权Kappa系数进行直肠伪影评估的一致性检验.采用χ2检验比较不同年资阅片医师PI-RADS评分、直肠伪影评分差异.采用多读者多病例受试者工作特征曲线(multi-reader multi-case receiver operating characteristic curve,MRMC-ROC)比较不同阅片者的诊断差异.采用受试者工作特征(receiver operating characteristic,ROC)曲线下面积(area under the curve,AUC)评估DL-CAD的诊断效能.采用DeLong检验比较AUC值差异.P<0.05为差异具有统计学意义.结果 本研究共纳入685例患者,其中前列腺癌组共199例,良性病变组共486例.在主观评价方面,低年资阅片者1的AUC无伪影为0.772,AUC有伪影为0.644,差异具有统计学意义(P=0.023).低年资阅片者2的AUC无伪影为0.809,AUC有伪影为0.682,差异具有统计学意义(P=0.007).而中高年资阅片者诊断效能差异均无统计学意义(P>0.05).在不同程度的直肠伪影评估方面,所有医师的诊断效能AUC差异均无统计学意义(0.071≤P<0.973).基于主观评分标准,两位医师对直肠伪影评分一致性为0.851.在直肠伪影亚组分析方面,外周带无伪影区域AUC高于有伪影区域(阅片者1:0.754 vs.0.532;阅片者2:0.771 vs.0.580),且差异存在统计学意义(P<0.05),剩余亚组比较差异均无统计学意义(P>0.05).在深度学习方面,DL-CAD的AUC无伪影为0.794,AUC有伪影为0.538,差异具有统计学意义(P<0.05).DL-CAD的AUC轻度伪影为0.546,AUC中度伪影为0.590,AUC重度伪影为0.481,轻、中、重度伪影对DL-CAD诊断效能差异均无统计学意义(P>0.05).结论 直肠磁敏感伪影对于主观视觉评价及DL-CAD评估均有显著性负面影响,对于主观视觉评价和DL-CAD评估影响方式存在差异.
Influence of rectal susceptibility artifacts on diagnosis of prostate cancer based on biparametric magnetic resonance imaging
Objective:To explore the impact of rectal susceptibility artifacts on the subjective evaluation and deep learning-based computer aided diagnosis(DL-CAD)in MRI-based prostate cancer diagnosis.Materials and Methods:A retrospective analysis was conducted on 685 patients who underwent biparametric magnetic resonance imaging(bpMRI).All patients have confirmed pathological results via either biopsy or surgical resection.Three groups of radiologists(Reader 1-6)with varying years of experience independently reviewed suspicious lesions on prostate MRI according to the Prostate Imaging Reporting and Data System(PI-RADS)version 2.1.The other two readers scored whether there were rectal artifacts on MRI and the degree of artifacts.A DL-CAD model based on prostate MRI was constructed to evaluate the impact of rectal artifacts on the deep learning-based diagnostic model.The weighted Kappa coefficient was used for the consistency test of rectal artifact assessment.Differences in PI-RADS scores and rectal artifact scores among radiologists with different years of experience were compared using the chi-square test.The diagnostic differences among readers were compared using the multi-reader multi-case receiver operating characteristic curve(MRMC-ROC).The area under the curve(AUC)was used to evaluate the diagnostic performance of DL-CAD.The DeLong test was used to compare the differences in AUC values.A significance level of P<0.05 was considered statistically significant.Results:This study included a total of 685 patients,comprising 199 cases of prostate cancer and 486 cases of benign lesions.In subjective evaluation,the AUC for junior Reader 1 was 0.772 without artifacts and 0.644 with artifacts,a statistically significant difference(P=0.023),while the AUC for junior Reader 2 was 0.809 without artifacts and 0.682 with artifacts,a statistically significant difference(P=0.007).The difference was not statistically significant(P>0.05)between the diagnostic performance of the middle and senior readers.Regarding the assessment of different degrees of rectal artifacts,there were no statistically significant differences in the diagnostic performance AUC among all readers(0.071≤P<0.973).Based on subjective scoring criteria,the other two readers rated the rectal artifact with a consistency of 0.851.In rectal artifact subgroup analysis,the AUC in the area without artifacts was higher than that in the area with artifacts in peripheral zone(Reader 1:0.754 vs.0.532;Reader 2:0.771 vs.0.580),and these differences were statistically significant(P<0.05).However,no statistically significant differences were observed in the remaining subgroups(P>0.05).In deep learning,the AUC without artifacts was 0.794 and the AUC with artifacts 0.538 for DL-CAD,and the difference was statistically significant(P<0.05).The AUC with mild artifacts were 0.546,the AUC with moderate artifacts were 0.590,and the AUC with severe artifacts were 0.481,and there was no significant difference in the diagnostic performance of DL-CAD(P>0.05).Conclusions:Rectal susceptibility artifacts have significant negative effects on subjective visual assessment and DL-CAD assessment.There are differences in the impact of rectal artifacts on subjective visual assessment and DL-CAD assessment.
rectal susceptibility artifactsprostate cancermagnetic resonance imagingprostate imaging report and data systemdeep learning
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