局灶性自身免疫性胰腺炎：影像学特征有助于与胰腺癌相鉴别。
Focal autoimmune pancreatitis: radiological characteristics help to distinguish from pancreatic cancer.
机构信息
Department of Radiology, Changhai Hospital, the Second Military Medical University, Shanghai 200433, China.
出版信息
World J Gastroenterol. 2013 Jun 21;19(23):3634-41. doi: 10.3748/wjg.v19.i23.3634.
AIM
To identify the radiological characteristics of focal autoimmune pancreatitis (f-AIP) useful for differentiation from pancreatic cancer (PC).
METHODS
Magnetic resonance imaging (MRI) and triple-phase computed tomography (CT) scans of 79 patients (19 with f-AIP, 30 with PC, and 30 with a normal pancreas) were evaluated retrospectively. A radiologist measured the CT attenuation of the pancreatic parenchyma, the f-AIP and PC lesions in triple phases. The mean CT attenuation values of the f-AIP lesions were compared with those of PC, and the mean CT attenuation values of pancreatic parenchyma in the three groups were compared. The diagnostic performance of CT attenuation changes from arterial phase to hepatic phase in the differentiation between f-AIP and PC was evaluated using receiver operating characteristic (ROC) curve analysis. We also investigated the incidence of previously reported radiological findings for differentiation between f-AIP and PC.
RESULTS
The mean CT attenuation values of f-AIP lesions in enhanced phases were significantly higher than those of PC (arterial phase: 60 ± 7 vs 48 ± 10, P < 0.05; pancreatic phase: 85 ± 6 vs 63 ± 15, P < 0.05; hepatic phase: 95 ± 7 vs 63 ± 13, P < 0.05). The mean CT attenuation values of f-AIP lesions were significantly lower those of uninvolved pancreas and normal pancreas in the arterial and pancreatic phase of CT (P < 0.001, P < 0.001), with no significant difference at the hepatic phase or unenhanced scanning (P = 0.4, P = 0.1). When the attenuation value increase was equal or more than 28 HU this was considered diagnostic for f-AIP, and a sensitivity of 87.5%, specificity of 100% and an area under the ROC curve of 0.974 (95%CI: 0.928-1.021) were achieved. Five findings were more frequently observed in f-AIP patients: (1) sausage-shaped enlargement; (2) delayed homogeneous enhancement; (3) hypoattenuating capsule-like rim; (4) irregular narrowing of the main pancreatic duct (MPD) and/or stricture of the common bile duct (CBD); and (5) MPD upstream dilation ≤ 5 mm.
CONCLUSION
Analysis of a combination of CT and MRI findings could improve the diagnostic accuracy of differentiating f-AIP from PC.
目的
确定有助于鉴别局灶性自身免疫性胰腺炎（f-AIP）与胰腺癌（PC）的影像学特征。
方法
回顾性分析 79 例患者（19 例 f-AIP、30 例 PC 和 30 例正常胰腺）的磁共振成像（MRI）和三期计算机断层扫描（CT）检查结果。一名放射科医生测量了胰腺实质、f-AIP 和 PC 病变的 CT 衰减值。比较 f-AIP 病变的平均 CT 衰减值与 PC 的 CT 衰减值，并比较三组胰腺实质的平均 CT 衰减值。使用受试者工作特征（ROC）曲线分析评估动脉期至肝期 CT 衰减变化在 f-AIP 和 PC 鉴别中的诊断性能。我们还研究了鉴别 f-AIP 和 PC 的先前报道的影像学发现的发生率。
结果
增强期 f-AIP 病变的平均 CT 衰减值明显高于 PC（动脉期：60±7 比 48±10，P<0.05；胰腺期：85±6 比 63±15，P<0.05；肝期：95±7 比 63±13，P<0.05）。f-AIP 病变的平均 CT 衰减值在动脉期和胰腺期明显低于未受累胰腺和正常胰腺（P<0.001，P<0.001），在肝期或平扫时无显著差异（P=0.4，P=0.1）。当衰减值增加等于或大于 28 HU 时，认为该值有助于诊断 f-AIP，此时的敏感性为 87.5%，特异性为 100%，ROC 曲线下面积为 0.974（95%CI：0.928-1.021）。f-AIP 患者更常出现以下 5 种表现：（1）香肠状肿大；（2）延迟均匀强化；（3）低衰减包膜样边缘；（4）主胰管（MPD）不规则狭窄和/或胆总管（CBD）狭窄；和（5）MPD 上游扩张≤5mm。
结论
综合分析 CT 和 MRI 表现可以提高鉴别 f-AIP 与 PC 的诊断准确性。
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