title: Contrast-enhanced MDCT in patients with pancreatic neuroendocrine tumours: correlation with histological findings and diagnostic performance in differentiation between tumour grades.
abstract: OBJECTIVE
  To identify the multidetector computed tomography (MDCT) features of pancreatic neuroendocrine tumours (pNETs), which correlate with tumour histology and enable preoperative grading.
  
  
  METHODS
  Thirty-nine patients with histologically confirmed pNET who underwent preoperative contrast-enhanced MDCT were included in this study. Nineteen tumours were classified as Grade 1 (G1) and 20 as Grade 2 (G2). Histopathology slides were reviewed to assess the intratumoural microvascular density (MVD) and the amount of tumour stroma. Computed tomography (CT) image analysis included tumour size, margin delineation, calcifications, homogeneity, contrast enhancement (CE) pattern, tumour absolute and relative enhancement, presence of cystic changes, pancreatic duct dilatation, regional and distant metastases. The diagnostic ability to predict tumour grade was measured for each MDCT finding and their combinations.
  
  
  RESULTS
  The mean arterial enhancement ratio had a mean±standard deviation of 1.53±0.45 in G1 and 1.01±0.33 in G2 pNETs (p=0.0003) and correlated with intratumoural microvascular density (MVD; r=0.55, p=0.0002). Tissue stroma percentage did not correlate with imaging findings. Late CE of the tumour (the peak attenuation observed in the venous phase) was significantly associated with G2. Tumour size >20 mm, arterial enhancement ratio <1.1, and late CE showed 74.4%, 79.5%, and 74.4% accuracy, respectively, in diagnosing G2 tumours, while the accuracy of at least two of these criteria used in combination was 82%. Based on these results, a diagnostic algorithm was proposed, which showed high interobserver agreement (k=0.82) in the prediction of tumour grade.
  
  
  CONCLUSIONS
  Contrast-enhanced MDCT features correlate with histological findings and enable the differentiation between G1 and G2 pNETs during preoperative examination.
authors.affiliation: Department of Radiology, A.V. Vishnevsky Institute of Surgery, Moscow, Russia; Department of Radiology, Faculty of Postgraduate Professional Training of Physicians, I.M. Sechenov First Moscow State Medical University, Moscow, Russia. Electronic address: dr.elena.belousova@gmail.com.
authors.forename: E
authors.initials: E
authors.lastname: Belousova
authors.affiliation: Department of Radiology, A.V. Vishnevsky Institute of Surgery, Moscow, Russia; Department of Radiology, Faculty of Postgraduate Professional Training of Physicians, I.M. Sechenov First Moscow State Medical University, Moscow, Russia.
authors.forename: G
authors.initials: G
authors.lastname: Karmazanovsky
authors.affiliation: Department of Abdominal Surgery, A.V. Vishnevsky Institute of Surgery, Moscow, Russia.
authors.forename: A
authors.initials: A
authors.lastname: Kriger
authors.affiliation: Department of Pathology, A.V. Vishnevsky Institute of Surgery, Moscow, Russia.
authors.forename: D
authors.initials: D
authors.lastname: Kalinin
authors.affiliation: Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
authors.forename: L
authors.initials: L
authors.lastname: Mannelli
authors.affiliation: Department of Pathology, A.V. Vishnevsky Institute of Surgery, Moscow, Russia.
authors.forename: A
authors.initials: A
authors.lastname: Glotov
authors.affiliation: Department of Radiology, A.V. Vishnevsky Institute of Surgery, Moscow, Russia.
authors.forename: N
authors.initials: N
authors.lastname: Karelskaya
authors.affiliation: Department of Pathology, A.V. Vishnevsky Institute of Surgery, Moscow, Russia; Department of Pathology, S.P. Botkin City Clinical Hospital, Moscow, Russia.
authors.forename: O
authors.initials: O
authors.lastname: Paklina
authors.affiliation: Department of Abdominal Surgery, A.V. Vishnevsky Institute of Surgery, Moscow, Russia.
authors.forename: A
authors.initials: A
authors.lastname: Kaldarov
mesh_terms: D003287:Contrast Media; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007455:Iodine; D008297:Male; D008875:Middle Aged; D061330:Multidetector Computed Tomography / Q000379:methods*; D060787:Neoplasm Grading; D018358:Neuroendocrine Tumors / Q000145:classification / Q000000981:diagnostic imaging* / Q000473:pathology*; D015588:Observer Variation; D010190:Pancreatic Neoplasms / Q000145:classification / Q000000981:diagnostic imaging* / Q000473:pathology*; D011856:Radiographic Image Enhancement / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013223:Statistics as Topic
chemical_list: D003287:Contrast Media; D007455:Iodine