Repeatability of Quantitative 18F-NaF PET: A Multicenter Study

J Nucl Med. 2016 Dec;57(12):1872-1879. doi: 10.2967/jnumed.116.177295. Epub 2016 Jul 21.


18F-NaF, a PET radiotracer of bone turnover, has shown potential as an imaging biomarker for assessing the response of bone metastases to therapy. This study aimed to evaluate the repeatability of 18F-NaF PET-derived SUV imaging metrics in individual bone lesions from patients in a multicenter study.

Methods: Thirty-five castration-resistant prostate cancer patients with multiple metastases underwent 2 whole-body (test-retest) 18F-NaF PET/CT scans 3 ± 2 d apart from 1 of 3 imaging sites. A total of 411 bone lesions larger than 1.5 cm3 were automatically segmented using an SUV threshold of 15 g/mL. Two levels of analysis were performed: lesion-level, in which measures were extracted from individual-lesion regions of interest (ROI), and patient-level, in which all lesions within a patient were grouped into a patient ROI for analysis. Uptake was quantified with SUVmax, SUVmean, and SUVtotal Test-retest repeatability was assessed using Bland-Altman analysis, intraclass correlation coefficient (ICC), coefficient of variation, critical percentage difference, and repeatability coefficient. The 95% limit of agreement (LOA) of the ratio between test and retest measurements was calculated.

Results: At the lesion level, the coefficient of variation for SUVmax, SUVmean, and SUVtotal was 14.1%, 6.6%, and 25.5%, respectively. At the patient level, it was slightly smaller: 12.0%, 5.3%, and 18.5%, respectively. ICC was excellent (>0.95) for all SUV metrics. Lesion-level 95% LOA for SUVmax, SUVmean, and SUVtotal was (0.76, 1.32), (0.88, 1.14), and (0.63, 1.71), respectively. Patient-level 95% LOA was slightly narrower, at (0.79, 1.26), (0.89, 1.10), and (0.70, 1.44), respectively. We observed significant differences in the variance and sample mean of lesion-level and patient-level measurements between imaging sites.

Conclusion: The repeatability of SUVmax, SUVmean, and SUVtotal for 18F-NaF PET/CT was similar between lesion- and patient-level ROIs. We found significant differences in lesion-level and patient-level distributions between sites. These results can be used to establish 18F-NaF PET-based criteria for assessing treatment response at the lesion and patient levels. 18F-NaF PET demonstrates repeatability levels useful for clinically quantifying the response of bone lesions to therapy.

Keywords: PET; metastatic prostate cancer; multicenter clinical trial; repeatability; sodium fluoride.

Publication types

  • Clinical Trial
  • Multicenter Study

MeSH terms

  • Aged
  • Aged, 80 and over
  • Biological Transport
  • Bone Neoplasms / diagnostic imaging
  • Bone Neoplasms / metabolism
  • Bone Neoplasms / secondary
  • Fluorine Radioisotopes*
  • Humans
  • Male
  • Middle Aged
  • Positron Emission Tomography Computed Tomography*
  • Prostatic Neoplasms, Castration-Resistant / pathology
  • Reproducibility of Results
  • Sodium Fluoride* / metabolism
  • Whole Body Imaging


  • Fluorine Radioisotopes
  • Sodium Fluoride