title: Dual-phase FDG-PET: delayed acquisition improves hepatic detectability of pathological uptake.
abstract: OBJECTIVE
  The aim of this study was to evaluate whether the acquisition of delayed images could improve the detectability of liver pathological uptakes.
  
  
  METHODS
  Ninety-five consecutive patients with suspected liver metastases underwent a dual-phase positron emission tomography (PET) scan. All patients underwent a whole-body PET/computed tomography (CT) scan (PET-1) acquired 1 h post [18F]fluorodeoxyglucose (FDG) injection, and a liver PET/CT scan [that is, one or two fields of view (FOV) of the upper abdomen; PET-2] acquired 2 h postinjection. In all cases, image reconstruction was performed as 3D reconstruction algorithm Fourier rebinning (FORE) iterative, FOV 50 cm, image matrix size 128 x 128. Both studies were evaluated qualitatively and semiquantitatively [background standard uptake values (SUV)mean of the liver, lesion SUVmax and SUVmean and ratio SUVmean lesion/background).
  
  
  RESULTS
  Thirty-seven of 95 patients (38.9%) presented liver lesions at both PET-1 and PET-2 exams, whereas there were two (2.2%) only at PET-2. Eighty-one liver lesions were identified at both PET studies, whereas there were nine (11.1%) only at PET-2. Furthermore, at PET-2, we had a statistically significant reduction of SUVmean background values (p < 0.001, Wilcoxon test) and a concomitant increase of SUVmean lesion values (p < 0.001, Wilcoxon test), ratio lesion to background (p < 0.001, Wilcoxon test).
  
  
  CONCLUSIONS
  Acquisition of delayed images improved the hepatic detection of pathological FDG uptake.
authors.affiliation: Centro PET, IRMET S.p.A., Via Onorato Vigliani, 89/A, 10135, Torino, Italy.
authors.forename: V
authors.initials: V
authors.lastname: Arena
authors.forename: A
authors.initials: A
authors.lastname: Skanjeti
authors.forename: R
authors.initials: R
authors.lastname: Casoni
authors.forename: A
authors.initials: A
authors.lastname: Douroukas
authors.forename: E
authors.initials: E
authors.lastname: Pelosi
mesh_terms: D000465:Algorithms; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000008:administration & dosage; D005583:Fourier Analysis; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D008113:Liver Neoplasms / Q000000981:diagnostic imaging* / Q000556:secondary; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography / Q000379:methods*; D011860:Radiography, Abdominal; D019275:Radiopharmaceuticals / Q000008:administration & dosage; D012680:Sensitivity and Specificity; D018709:Statistics, Nonparametric; D013997:Time Factors; D014057:Tomography, X-Ray Computed
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18