title: Detection of pancreatic neuroendocrine tumors (PNET) using semi-quantitative [68Ga]DOTATOC PET in combination with multiphase contrast-enhanced CT.
abstract: OBJECTIVE
  Pancreatic neuroendocrine tumors (PNETs) pose a diagnostic challenge with respect to the physiologic somatostatin receptor expression in the uncinate process representing a potential pitfall for receptor imaging with PET/CT.
  
  
  METHODS
  We identified 49 PNETs from a total of 316 consecutive [68Ga]DOTATOC PET/CT examinations for whom the detections rates of PET and multiphase contrast enhanced (CE-) CT could be retrospectively compared and 38 PNETs for which SUVmax and SUVmax target-to-liver ratios could be calculated for the tumors and the uncinate process.
  
  
  RESULTS
  The detection rate of PET (83.7%) was higher than of the different CT phases (arterial: 59.2%, P=0.017; portal-venous: 38.8%, P<0.001; venous: 46.9%, P=0.001; multiphase: 71.4%, P=0.286). Compared to the other method PET revealed 28.6% additional lesions and multiphase CE-CT 16.3%. The portal-venous phase revealed only lesions that were also detected in the arterial or venous phase. The detection rate for PNETs in the uncinate process (N.=9) was 66.7% for PET versus 55.6% for multiphase CE-CT. SUVmax and SUVmax target-to-liver ratios differed significantly (P<0.001) for PNETs (mean, range: SUVmax, 14.6, 1.4-69.3; SUVmax target-to-liver ratio, 3.2, 0.69-23.1) and uncinate process (4.32, 0.8-13.5; 0.94, 0.51-1.56), however with a wide overlap.
  
  
  CONCLUSIONS
  Patients with PNETs should undergo [68Ga]DOTATOC PET/CT with at least an arterial and venous phase CT scan. SUVmax and SUVmax target-to-liver ratios provide additional information but do no reliably separate PNETs from normal tracer uptake in the uncinate process.
authors.affiliation: Department of Radiology Charité Medical University, Berlin, Germany - Nils.Schreiter@charite.de.
authors.forename: V
authors.initials: V
authors.lastname: Froeling
authors.forename: R
authors.initials: R
authors.lastname: Röttgen
authors.forename: F
authors.initials: F
authors.lastname: Collettini
authors.forename: J
authors.initials: J
authors.lastname: Rothe
authors.forename: B
authors.initials: B
authors.lastname: Hamm
authors.forename: W
authors.initials: W
authors.lastname: Brenner
authors.forename: N
authors.initials: N
authors.lastname: Schreiter
mesh_terms: D003287:Contrast Media; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging / Q000379:methods*; D018358:Neuroendocrine Tumors / Q000175:diagnosis*; D015282:Octreotide / Q000031:analogs & derivatives*; D009942:Organometallic Compounds; D010190:Pancreatic Neoplasms / Q000175:diagnosis*; D049268:Positron-Emission Tomography / Q000379:methods*; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media; C499142:Ga(III)-DOTATOC; D009942:Organometallic Compounds; D019275:Radiopharmaceuticals; D015282:Octreotide