title: PSMA PET/CT with Glu-urea-Lys-(Ahx)-[⁶⁸Ga(HBED-CC)] versus 3D CT volumetric lymph node assessment in recurrent prostate cancer.
abstract: OBJECTIVE
  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.
  
  
  CONCLUSIONS
  (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.
authors.affiliation: Department of Nuclear Medicine, INF 400, University Hospital Heidelberg, University of Heidelberg, 69120, Heidelberg, Germany. frederik@egiesel.com.|Cooperation Unit Nuclear Medicine, DKFZ, Heidelberg, Germany. frederik@egiesel.com.
authors.forename: Frederik L
authors.initials: FL
authors.lastname: Giesel
authors.affiliation: Department of Nuclear Medicine, INF 400, University Hospital Heidelberg, University of Heidelberg, 69120, Heidelberg, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Fiedler
authors.affiliation: Department of Nuclear Medicine, INF 400, University Hospital Heidelberg, University of Heidelberg, 69120, Heidelberg, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Stefanova
authors.affiliation: Department of RadioOncology, University of Heidelberg, Heidelberg, Germany.
authors.forename: F
authors.initials: F
authors.lastname: Sterzing
authors.affiliation: Institute for Transuranium Elements (ITU), European Commission, Karlsruhe, Germany.|Cooperation Unit Nuclear Medicine, DKFZ, Heidelberg, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Rius
authors.affiliation: Radiopharmaceutical Chemistry, German Cancer Research Center (dkfz), Heidelberg, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Kopka
authors.affiliation: Radiopharmaceutical Chemistry, German Cancer Research Center (dkfz), Heidelberg, Germany.
authors.forename: J H
authors.initials: JH
authors.lastname: Moltz
authors.affiliation: Department of Nuclear Medicine, INF 400, University Hospital Heidelberg, University of Heidelberg, 69120, Heidelberg, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Afshar-Oromieh
authors.affiliation: Molecular Imaging Program, National Cancer Institute, Bethesda, USA.
authors.forename: P L
authors.initials: PL
authors.lastname: Choyke
authors.affiliation: Department of Nuclear Medicine, INF 400, University Hospital Heidelberg, University of Heidelberg, 69120, Heidelberg, Germany.|Cooperation Unit Nuclear Medicine, DKFZ, Heidelberg, Germany.
authors.forename: U
authors.initials: U
authors.lastname: Haberkorn
authors.affiliation: Department of Nuclear Medicine, INF 400, University Hospital Heidelberg, University of Heidelberg, 69120, Heidelberg, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Kratochwil
mesh_terms: D000368:Aged; D004492:Edetic Acid / Q000031:analogs & derivatives*; D005709:Gallium Isotopes; D005710:Gallium Radioisotopes; D006801:Humans; D021621:Imaging, Three-Dimensional; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D009842:Oligopeptides; D049268:Positron-Emission Tomography; D011471:Prostatic Neoplasms / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology*; D011859:Radiography; D012008:Recurrence; D012189:Retrospective Studies
chemical_list: D005709:Gallium Isotopes; D005710:Gallium Radioisotopes; D009842:Oligopeptides; C000718244:gallium 68 PSMA-11; D004492:Edetic Acid
keywords: 68Ga-PSMA-11 PET/CT; Lymph node evaluation; Lymph node metastasis; Recurrent prostate cancer