Imaging features of intestinal-type and pancreaticobiliary-type invasive adenocarcinoma of the ampullary region

Abstract

Objective To analyze the computed tomography (CT) and magnetic resonance imaging (MRI) features of intestinal-type and pancreaticobiliary-type invasive adenocarcinomas of the ampullary region (IAARs) and investigate the value of the differential diagnosis. Methods The retrospective cross-sectional study was adopted. The clinicopathological data of 33 patients with IAAR who were admitted to the Lanzhou University Second Hospital (20 patients) and Affiliated Hospital of Ningbo University (13 patients) between September 2013 and August 2015 were collected. The patients underwent plain and enhanced scans of CT and MRI. (1) Observation indictors included tumor size, shape, growth pattern, boundary, internal structure, density and/or signal, style and/or degree of contrast enhancement, changes of bile and/or pancreatic duct, invasion and metastasis. (2) The clinical and imaging features of intestinal-type and pancreaticobiliary-type IAARs were compared. (3) Operation was performed after preoperative examinations, and patients received the postoperative pathological examination and immunohistochemistry. Measurement data with normal distribution were presented as ±s. Comparison between groups was evaluated with an independent sample t test, and count data were analyzed using the chi-square test. Results (1) Of 33 patients with IAAR, 19 received plain scan of CT, including 17 receiving simultaneous enhanced scan of CT. Fourteen patients [9 receiving diffussion-weighted imaging (DWI) sequence of MRI] received plain scan of MRI, including 12 receiving simultaneous enhanced scan of MRI. The maximum diameter of IAAR in 33 patients was (2.8±1.4)cm. Fourteen tumors were round-like or oval shape and 19 tumors were irregular shape. The intracavity type, extracavity type and mixed type of tumors were detected in 24, 6 and 3 patients, respectively. There were clear boundary of tumors in 17 patients and fuzzy boundary of tumors in 16 patients. Tumors of 5 patients had appeared necrotic and/or cystic, no hemorrhage or calcification was found in tumors of 33 patients. Density and signal of tumors were homogeneous in 18 patients and inhomogeneous in 15 patients. Of 29 patients receiving enhanced scan of CT or MRI, homogeneous enhancement and inhomogeneous enhancement were respectively detected in 14 and 15 patients, and mild enhancement, moderate enhancement and no enhancement were respectively detected in 15, 14 and 0 patients. Tumors of 9 patients in DWI showed slightly high or high signal. Thirty patients had secondary bile duct dilatation (3 with mild dilatation, 6 with moderate dilatation and 21 with severe dilatation), and 3 patients had no changes of bile duct. Twenty-six patients had secondary pancreatic duct dilatation and 7 had no changes of pancreatic duct. Sixteen patients had tumor invasion to pancreatic tissues and 7 had lymph node metastases. (2) Of 33 patients with IAAR, 19 had intestinal-type IAAR (8 males and 11 females) and 14 had pancreaticobiliary-type IAAR (11 males and 3 females). There was statistically significant difference in the gender between the 2 types of IAAR (χ2=4.388, P<0.05). The intracavity type, extracavity type and mixed type of tumors, clear boundary and fuzzy boundary of tumors, homogeneous and inhomogeneous density and/or signal of tumors, with and without tumor invasion to pancreatic tissues were respectively detected in 17, 0, 2, 13, 6, 14, 5, 6, 13 patients with intestinal-type IAAR and 7, 6, 1, 4, 10, 4, 10, 10, 4 patients with pancreaticobiliary-type IAAR, with statistically significant differences between the 2 types of IAAR (χ2=9.971, 5.125, 6.617, 5.125, P<0.05). (3) All the patients underwent surgery and received comprehensive diagnosis and tumor classification after pathological examination and immunohistochemistry. Conclusion There are certain characteristics of CT and MRI in intestinal-type and pancreaticobiliary-type IAARs, and gender, tumor growth pattern, boundary, density and/or signal, tumor invasion to pancreatic tissues have certain reference values for the differential diagnosis of intestinal- type and pancreaticobiliary-type IAARs. Key words: Ampullary neoplasms; Invasive adenocareinoma; Tomography, X-ray computed; Magne-tic resonance imaging