title: Comparison of 3'-deoxy-3'-[¹⁸F]fluorothymidine positron emission tomography (FLT PET) and FDG PET/CT for the detection and characterization of pancreatic tumours.
abstract: OBJECTIVE
  Despite recent advances in clinical imaging modalities, differentiation of pancreatic masses remains difficult. Here, we tested the diagnostic accuracy of molecular-based imaging including 3'-deoxy-3'-[(18)F]fluorothymidine (FLT) positron emission tomography (PET) and [(18)F]fluorodeoxyglucose (FDG) PET/CT in patients with suspected pancreatic masses scheduled to undergo surgery.
  
  
  METHODS
  A total of 46 patients with pancreatic tumours suspicious for malignancy and scheduled for resective surgery were recruited prospectively. In 41 patients, FLT PET and FDG PET/CT scans were performed. A diagnostic CT performed on a routine basis was available in 31 patients. FLT PET and FDG PET/CT emission images were acquired according to standard protocols. Tracer uptake in the tumour [FDG and FLT standardized uptake value (SUV)] was quantified by the region of interest (ROI) technique. For FDG PET/CT analysis, correct ROI placement was ensured via side-by-side reading of corresponding CT images.
  
  
  RESULTS
  Of 41 patients, 33 had malignancy, whereas 8 patients had benign disease. Visual analysis of FDG and FLT PET resulted in sensitivity values of 91% (30/33) and 70% (23/33), respectively. Corresponding specificities were 50% (4/8) for FDG PET and 75% (6/8) for FLT PET. In the subgroup of patients with contrast-enhanced CT (n = 31), sensitivities were 96% (PET/CT), 88% (CT alone), 92% (FDG PET) and 72% (FLT PET), respectively. Mean FLT uptake in all malignant tumours was 3.0 (range SUV(max) 1.1-6.5; mean FDG SUV(max) 7.9, range 3.3-17.8; p < 0.001).
  
  
  CONCLUSIONS
  For differentiation of pancreatic tumours, FDG PET and FDG PET/CT showed a higher sensitivity but lower specificity than FLT PET. Interestingly, visual analysis of FLT PET led to two false-positive findings by misinterpreting physiological bowel uptake as pathological FLT uptake in the pancreas. Due to the limited number of patients, the clinical value of adding FLT PET to the diagnostic workup of pancreatic tumours remains to be determined.
authors.affiliation: Department of Nuclear Medicine, Technische Universität München, Ismaningerstr. 22, 81675 Munich, Germany. ken.herrmann@web.de
authors.forename: K
authors.initials: K
authors.lastname: Herrmann
authors.forename: M
authors.initials: M
authors.lastname: Erkan
authors.forename: M
authors.initials: M
authors.lastname: Dobritz
authors.forename: T
authors.initials: T
authors.lastname: Schuster
authors.forename: J T
authors.initials: JT
authors.lastname: Siveke
authors.forename: A J
authors.initials: AJ
authors.lastname: Beer
authors.forename: H J
authors.initials: HJ
authors.lastname: Wester
authors.forename: R M
authors.initials: RM
authors.lastname: Schmid
authors.forename: H
authors.initials: H
authors.lastname: Friess
authors.forename: M
authors.initials: M
authors.lastname: Schwaiger
authors.forename: J
authors.initials: J
authors.lastname: Kleeff
authors.forename: A K
authors.initials: AK
authors.lastname: Buck
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D003287:Contrast Media; D015224:Dideoxynucleosides; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging / Q000379:methods*; D009367:Neoplasm Staging; D010190:Pancreatic Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery; D049268:Positron-Emission Tomography; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed
chemical_list: D003287:Contrast Media; D015224:Dideoxynucleosides; D019788:Fluorodeoxyglucose F18; C002854:alovudine