Quantitative Test-Retest Measurement of 68Ga-PSMA-HBED-CC in Tumor and Normal Tissue

J Nucl Med. 2020 Aug;61(8):1145-1152. doi: 10.2967/jnumed.119.236083. Epub 2019 Dec 5.


The PET radiotracer 68Ga-PSMA (prostate-specific membrane antigen)-HBED-CC (N,N'-bis [2-hydroxy-5-(carboxyethyl)benzyl]ethylenediamine-N,N'-diacetic acid) shows potential as an imaging biomarker for recurrent and metastatic prostate cancer. The purpose of this study was to determine the repeatability of 68Ga-PSMA-HBED-CC in a test-retest trial in subjects with metastatic prostate adenocarcinoma. Methods: Subjects with metastatic prostate cancer underwent 2 PET/CT scans with 68Ga-PSMA-HBED-CC within 14 d (mean, 6 ± 4 d). Lesions in bone, nodes, prostate/bed, and visceral organs, as well as representative normal tissues (salivary glands and spleen), were segmented separately by 2 readers. Absolute and percentage differences in SUVmax and SUVmean were calculated for all test-retest regions. Repeatability was assessed using percentage difference, within-subject coefficient of variation (wCV), repeatability coefficient (RC), and Bland-Altman analysis. Results: Eighteen subjects were evaluated, 16 of whom demonstrated local or metastatic disease on 68Ga-PSMA-HBED-CC PET/CT. In total, 136 lesions were segmented in bone (n = 99), nodes (n = 27), prostate/bed (n = 7), and viscera (n = 3). The wCV for SUVmax was 11.7% for bone lesions and 13.7% for nodes. The RC was ±32.5% SUVmax for bone lesions and ±37.9% SUVmax for nodal lesions, meaning 95% of the normal variability between 2 measurements will be within these numbers, so larger differences are likely attributable to true biologic changes in tumor rather than normal physiologic or measurement variability. wCV in the salivary glands and spleen was 8.9% and 10.7% SUVmean, respectively. Conclusion: Repeatability measurements for PET/CT test-retests with 68Ga-PSMA-HBED-CC showed a wCV of 12%-14% SUVmax and an RC of ±33%-38% SUVmax in bone and nodal lesions. These estimates are an important aspect of 68Ga-PSMA-HBED-CC as a quantitative imaging biomarker. These estimates are similar to those reported for 18F-FDG, suggesting that 68Ga-PSMA-HBED-CC PET/CT may be useful in monitoring response to therapy.

Keywords: PET/CT; PSMA HBED-CC; PSMA-11; SUV; repeatability.

Publication types

  • Clinical Trial

MeSH terms

  • Biological Transport
  • Edetic Acid / analogs & derivatives*
  • Edetic Acid / metabolism
  • Gallium Isotopes
  • Gallium Radioisotopes
  • Humans
  • Male
  • Middle Aged
  • Oligopeptides / metabolism*
  • Positron Emission Tomography Computed Tomography*
  • Prostate / cytology
  • Prostate / diagnostic imaging
  • Prostate / metabolism
  • Prostate / pathology
  • Prostatic Neoplasms / diagnostic imaging*
  • Prostatic Neoplasms / pathology*
  • Reproducibility of Results


  • Gallium Isotopes
  • Gallium Radioisotopes
  • Oligopeptides
  • gallium 68 PSMA-11
  • Edetic Acid