PSMA PET/CT with Glu-urea-Lys-(Ahx)-[⁶⁸Ga(HBED-CC)] versus 3D CT volumetric lymph node assessment in recurrent prostate cancer

Eur J Nucl Med Mol Imaging. 2015 Nov;42(12):1794-800. doi: 10.1007/s00259-015-3106-6. Epub 2015 Jul 11.

Abstract

Purpose: PET/CT with the PSMA ligand is a powerful new method for the early detection of nodal metastases in patients with biochemical relapse. The purpose of this retrospective investigation was to evaluate the volume and dimensions of nodes identified by Glu-urea-Lys-(Ahx)-[(68)Ga(HBED-CC)] ((68)Ga-PSMA-11) in the setting of recurrent prostate cancer.

Methods: All PET/CT images were acquired 60 ± 10 min after intravenous injection of (68)Ga-PSMA-11 (mean dose 176 MBq). In 21 patients with recurrent prostate cancer and rising PSA, 49 PSMA-positive lymph nodes were identified. Using semiautomated lymph node segmentation software, node volume and short-axis and long-axis dimensions were measured and compared with the maximum standardized uptake values (SUVmax). Round nodes greater than or equal to 8 mm were considered positive by morphological criteria alone. The percentage of nodes identified by elevated SUVmax but not by conventional morphological criteria was determined.

Results: The mean volume of (68)Ga-PSMA-11-positive nodes was 0.5 ml (range 0.2 - 2.3 ml), and the mean short-axis diameter was 5.8 mm (range 2.4 - 13.3 mm). In 7 patients (33.3 %) with 31 PSMA-positive nodes only 11 (36 %) were morphologically positive based on diameters >8 mm on CT. In the remaining 14 patients (66.7 %), 18 (37 %) of PSMA positive lymph nodes had short-axis diameters <8 mm with a mean short-axis diameter of 5.0 mm (range 2.4 - 7.9 mm). Thus, in this population, (68)Ga-PSMA-11 PET/CT detected nodal recurrence in two-thirds of patients who would have been missed using conventional morphological criteria.

Conclusion: (68)Ga-PSMA-11 PET/CT is more sensitive than CT based 3D volumetric lymph node evaluation in determining the node status of patients with recurrent prostate cancer, and is a promising method of restaging prostate cancers in this setting.

Keywords: 68Ga-PSMA-11 PET/CT; Lymph node evaluation; Lymph node metastasis; Recurrent prostate cancer.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Edetic Acid / analogs & derivatives*
  • Humans
  • Imaging, Three-Dimensional*
  • Lymphatic Metastasis
  • Male
  • Middle Aged
  • Multimodal Imaging*
  • Oligopeptides*
  • Positron-Emission Tomography*
  • Prostatic Neoplasms / diagnosis*
  • Prostatic Neoplasms / diagnostic imaging
  • Prostatic Neoplasms / pathology*
  • Radiography
  • Recurrence
  • Retrospective Studies

Substances

  • Oligopeptides
  • Edetic Acid
  • Glu-NH-CO-NH-Lys-(Ahx)-((68)Ga(HBED-CC))