title: Additional value of FDG PET/CT to contrast-enhanced CT in the differentiation between benign and malignant intraductal papillary mucinous neoplasms of the pancreas with mural nodules.
abstract: OBJECTIVE
  This study aimed at determining the additional value of FDG PET/CT to contrast-enhanced CT in the differentiation between benign and malignant intraductal papillary mucinous neoplasms (IPMNs) of the pancreas with mural nodules.
  
  
  METHODS
  This retrospective review of medical records was approved by our institutional review board. The preoperative PET/CT images of 16 non-diabetic patients with surgically proven IPMN, where mural nodules of 3 mm or larger were shown by preoperative contrast-enhanced CT, were retrospectively evaluated. The 16 patients were divided into two groups: 7 patients with benign IPMN [adenoma (n = 1) and borderline tumor (n = 6)] and 9 patients with malignant IPMN [carcinoma in situ (CIS) (n = 8) and invasive carcinoma (n = 1)]. Nuclear medicine physician blinded to the pathologic assessment of malignancy of IPMN set a spherical volume of interest (VOI) over the mural nodules on PET/CT images and recorded the peak standardized uptake value (SUV(max)) in the VOI, referring the contrast-enhanced CT images. Statistical differences in the size of mural nodule, the diameter of main pancreatic duct (MPD), and SUV(max) of the tumors between benign IPMNs and malignant IPMNs were compared using the Mann-Whitney U test. Statistical significance was set at p < 0.05. Additionally, the diagnostic accuracy of FDG PET for the detection of malignancy was calculated.
  
  
  RESULTS
  The SUV(max) of the malignant IPMNs with mural nodules of 3 mm or larger was higher than that of benign IPMNs (2.7 ± 0.6 vs. 1.9 ± 0.3, p < 0.01). Meanwhile, there was no significant difference in mural nodule diameter and MPD diameter between the two groups. FDG PET/CT showed an excellent diagnostic accuracy for the differentiation between malignant and benign IPMNs with mural nodules: the sensitivity, specificity, PPV, NPV, and accuracy in malignant IPMN with mural nodule of FDG PET/CT were 77.8, 100, 100, 77.8, and 87.5 for the cutoff value of 2.3; and 100, 57.1, 75.0, 100, and 81.3 for the cutoff value of 2.0, respectively.
  
  
  CONCLUSIONS
  The result of this study indicates that FDG PET/CT can provide additional information for the differentiation between benign and malignant IPMNs of the pancreas with mural nodules.
authors.affiliation: Department of Radiology, Tohoku University Graduate School of Medicine, Seiryomachi, Aoba-ku, Sendai, Miyagi, Japan. takanami@rad.med.tohoku.ac.jp
authors.forename: Kentaro
authors.initials: K
authors.lastname: Takanami
authors.forename: Tomomichi
authors.initials: T
authors.lastname: Hiraide
authors.forename: Masashi
authors.initials: M
authors.lastname: Tsuda
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Nakamura
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Kaneta
authors.forename: Kei
authors.initials: K
authors.lastname: Takase
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Fukuda
authors.forename: Shoki
authors.initials: S
authors.lastname: Takahashi
mesh_terms: D002288:Adenocarcinoma, Mucinous / Q000175:diagnosis* / Q000000981:diagnostic imaging; D021441:Carcinoma, Pancreatic Ductal / Q000175:diagnosis* / Q000000981:diagnostic imaging; D002291:Carcinoma, Papillary / Q000175:diagnosis* / Q000000981:diagnostic imaging; D003287:Contrast Media; D003937:Diagnosis, Differential; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D049268:Positron-Emission Tomography; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed
chemical_list: D003287:Contrast Media; D019788:Fluorodeoxyglucose F18