Dual-phase FDG-PET: delayed acquisition improves hepatic detectability of pathological uptake

Radiol Med. 2008 Sep;113(6):875-86. doi: 10.1007/s11547-008-0287-0. Epub 2008 Jul 10.
[Article in English, Italian]


Purpose: The aim of this study was to evaluate whether the acquisition of delayed images could improve the detectability of liver pathological uptakes.

Materials and 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.

Publication types

  • Comparative Study
  • Evaluation Study

MeSH terms

  • Algorithms
  • Female
  • Fluorodeoxyglucose F18* / administration & dosage
  • Fourier Analysis
  • Humans
  • Image Processing, Computer-Assisted
  • Imaging, Three-Dimensional
  • Liver Neoplasms / diagnostic imaging*
  • Liver Neoplasms / secondary
  • Male
  • Middle Aged
  • Positron-Emission Tomography / methods*
  • Radiography, Abdominal
  • Radiopharmaceuticals* / administration & dosage
  • Sensitivity and Specificity
  • Statistics, Nonparametric
  • Time Factors
  • Tomography, X-Ray Computed


  • Radiopharmaceuticals
  • Fluorodeoxyglucose F18