title: Enhancing pancreatic mass with normal serum CA19-9: key MDCT features to characterize pancreatic neuroendocrine tumours from its mimics.
abstract: OBJECTIVE
  To determine key MDCT features for characterizing pancreatic neuroendocrine tumours (PNET) from their mimics, which manifest as enhancing pancreatic mass with normal serum CA19-9 level.
  
  
  METHODS
  This retrospective study had institutional review board approval and informed consent was waived. Preoperative multiphase MDCT of 74 patients with enhancing pancreatic masses and normal serum CA19-9 levels were included. Surgical pathologies were PNET (n = 42), microcystic serous cystadenomas (m-SCN, n = 12) and solid pseudopapillary epithelial neoplasms (SPEN, n = 20). Two radiologists independently evaluated CT images with a checklist of findings. Frequencies of findings with each disease entity were compared. Diagnostic accuracy was assessed using the key MDCT features alone and in combination. Inter-observer agreement was evaluated.
  
  
  RESULTS
  The most common findings for PNET were mosaic morphological pattern (33/42, 78.6%) and enhancement peak in pancreatic arterial phase (PAP, 32/42, 76.2%), for m-SCN were honeycomb pattern (9/12, 75.0%) and enhancement peak in PAP (10/12, 83.3%) and for SPEN were melting icecream pattern (16/20, 80.0%) and hypo-enhancement in all phases (18/20, 90.0). Using a combination of morphological patterns and enhancement features, PNET was identified with 88% sensitivity and 81% specificity, m-SCN was identified with 83% sensitivity and 94% specificity, and SPEN was identified with 90% sensitivity and 91% specificity. Inter-observer agreement concerning CT findings was good to excellent (κ = 0.68 to 0.81, all p < 0.01).
  
  
  CONCLUSIONS
  Morphological features and enhancement patterns on MDCT are key features for characterizing enhancing pancreatic mass with normal serum CA19-9. PNET could be differentiated from its mimics with high accuracy.
authors.affiliation: Department of Radiology, Peking Union Medical College Hospital, Shuaifuyuan No. 1, Dongcheng District, Beijing, 100730, China.
authors.forename: Liang
authors.initials: L
authors.lastname: Zhu
authors.affiliation: Department of Radiology, Peking Union Medical College Hospital, Shuaifuyuan No. 1, Dongcheng District, Beijing, 100730, China. bjdanna95@hotmail.com.
authors.forename: Hua-Dan
authors.initials: HD
authors.lastname: Xue
authors.affiliation: Department of Radiology, Peking Union Medical College Hospital, Shuaifuyuan No. 1, Dongcheng District, Beijing, 100730, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Liu
authors.affiliation: Department of Radiology, Peking Union Medical College Hospital, Shuaifuyuan No. 1, Dongcheng District, Beijing, 100730, China.
authors.forename: Xuan
authors.initials: X
authors.lastname: Wang
authors.affiliation: Department of Radiology, Peking Union Medical College Hospital, Shuaifuyuan No. 1, Dongcheng District, Beijing, 100730, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Sui
authors.affiliation: Department of Radiology, Peking Union Medical College Hospital, Shuaifuyuan No. 1, Dongcheng District, Beijing, 100730, China.
authors.forename: Qin
authors.initials: Q
authors.lastname: Wang
authors.affiliation: Department of Radiology, Peking Union Medical College Hospital, Shuaifuyuan No. 1, Dongcheng District, Beijing, 100730, China.
authors.forename: Daming
authors.initials: D
authors.lastname: Zhang
authors.affiliation: Department of Radiology, Peking Union Medical College Hospital, Shuaifuyuan No. 1, Dongcheng District, Beijing, 100730, China.
authors.forename: Ping
authors.initials: P
authors.lastname: Li
authors.affiliation: Department of Radiology, Peking Union Medical College Hospital, Shuaifuyuan No. 1, Dongcheng District, Beijing, 100730, China.
authors.forename: Zheng-Yu
authors.initials: ZY
authors.lastname: Jin
mesh_terms: D000328:Adult; D000368:Aged; D015295:Antigens, Tumor-Associated, Carbohydrate / Q000097:blood*; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D061330:Multidetector Computed Tomography; D018358:Neuroendocrine Tumors / Q000097:blood* / Q000000981:diagnostic imaging* / Q000473:pathology; D010190:Pancreatic Neoplasms / Q000097:blood* / Q000000981:diagnostic imaging* / Q000473:pathology; D012189:Retrospective Studies; D047368:Tumor Burden; D055815:Young Adult
chemical_list: D015295:Antigens, Tumor-Associated, Carbohydrate; C578959:carbohydrate antigen 199, human
keywords: CA19-9; Diagnosis; Multidetector computed tomography; Pancreatic neoplasms