title: Computed tomography staging of pancreatic cancer: a validation study addressing interobserver agreement.
abstract: OBJECTIVE
  Ductal adenocarcinoma in the head of the pancreas (PDAC) is usually unresectable at the time of diagnosis due to the involvement of the peripancreatic vessels. Various preoperative classification algorithms have been developed to describe the relationship of the tumor to these vessels, but most of them lack a surgically based approach. We present a CT-based classification algorithm for PDAC based on surgical resectability principles with a focus on interobserver variability.
  
  
  METHODS
  Thirty patients with PDAC undergoing pancreaticoduodenectomy were examined by using a standard CT protocol. Nine radiologists, representing three different levels of expertise, evaluated the CT examinations and the tumors were classified into four categories (A-D) according to the proposed system. For the interobserver agreement, the Intraclass Correlation Coefficient (ICC) was estimated.
  
  
  RESULTS
  The overall ICC was 0.94 and the ICCs among the trainees, experienced radiologists, and experts were 0.85, 0.76, and 0.92, respectively. All tumors classified as category A1 showed no signs of vascular invasion at surgery. In category A2, 40% of the tumors had corresponding infiltration and required resection of the superior mesenteric vein/portal vein (SMV/PV). One of two tumors in category B2 and two of three in category C required SMV/PV resection. All six patients in category D had both arterial and venous involvement.
  
  
  CONCLUSIONS
  There is almost perfect agreement among radiologists with different levels of expertise in regards to the local staging of PDAC. For tumors in a more advanced preoperative category, an increased risk for vascular involvement was noticed at surgery.
authors.affiliation: Department of Clinical Science, Intervention and Technology at Karolinska Institutet, Division of Medical Imaging and Technology, 14186 Stockholm, Sweden; Department of Radiology, Karolinska University Hospital, Huddinge, 14186 Stockholm, Sweden.
authors.forename: L
authors.initials: L
authors.lastname: Loizou
authors.forename: N
authors.initials: N
authors.lastname: Albiin
authors.forename: C
authors.initials: C
authors.lastname: Ansorge
authors.forename: M
authors.initials: M
authors.lastname: Andersson
authors.forename: R
authors.initials: R
authors.lastname: Segersvärd
authors.forename: B
authors.initials: B
authors.lastname: Leidner
authors.forename: A
authors.initials: A
authors.lastname: Sundin
authors.forename: L
authors.initials: L
authors.lastname: Lundell
authors.forename: N
authors.initials: N
authors.lastname: Kartalis
mesh_terms: D000328:Adult; D000368:Aged; D000465:Algorithms; D003131:Combined Modality Therapy; D003287:Contrast Media; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging / Q000379:methods*; D015588:Observer Variation; D010179:Pancreas / Q000098:blood supply / Q000473:pathology; D010190:Pancreatic Neoplasms / Q000145:classification / Q000000981:diagnostic imaging* / Q000628:therapy; D016577:Pancreaticoduodenectomy / Q000379:methods; D011379:Prognosis; D011446:Prospective Studies; D012039:Regional Blood Flow; D015203:Reproducibility of Results; D016019:Survival Analysis; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media
keywords: Blood vessels; Classification; Diagnostic imaging; Pancreatic ductal carcinoma; Surgery