title: (68)Ga-PSMA-11 dynamic PET/CT imaging in biochemical relapse of prostate cancer.
abstract: OBJECTIVE
  We aim to investigate the pharmacokinetics and distribution of the recently clinically introduced radioligand (68)Ga-PSMA-11 in men with recurrent prostate cancer (PC) by means of dynamic and whole-body PET/CT. The correlation between PSA levels and (68)Ga-PSMA-11 PET parameters is also investigated.
  
  
  METHODS
  31 patients with biochemical failure after primary PC treatment with curative intent (median age 71.0 years) were enrolled in the analysis. The median PSA value was 2.0 ng/mL (range = 0.1 - 130.0 ng/mL) and the median Gleason score was 7 (range = 5 - 9). 8/31 (25.8 %) of the included patients had a PSA value < 0.5 ng/ml. All patients underwent dynamic PET/CT (dPET/CT) scanning (60 min) of the pelvis and lower abdomen as well as whole-body PET/CT with (68)Ga-PSMA-11. dPET/CT assessment was based on qualitative evaluation, SUV calculation, and quantitative analysis based on a two-tissue compartment model and a non-compartmental approach leading to the extraction of fractal dimension (FD).
  
  
  RESULTS
  22/31 patients (71.0 %) were (68)Ga-PSMA-11-positive, while 9/31 (29.0 %) patients were (68)Ga-PSMA-11-negative. The median PSA value in the (68)Ga-PSMA-11-positive group was significantly higher (median = 2.35 ng/mL; range = 0.19 - 130.0 ng/mL) than in the (68)Ga-PSMA-11-negative group (median value: 0.34 ng/mL; range = 0.10 - 4.20 ng/mL). A total of 76 lesions were semi-quantitatively evaluated. PC recurrence-associated lesions demonstrated a mean SUVaverage = 12.4 (median = 9.0; range = 2.2 - 84.5) and mean SUVmax = 18.8 (median = 14.1; range = 3.1 - 120.3). Dynamic PET/CT studies of the pelvis revealed the following mean values for the PC recurrence-suspicious lesions: K1 = 0.26, k3 = 0.30, influx = 0.14 and FD = 1.24. Time-activity curves derived from PC-recurrence indicative lesions revealed an increasing (68)Ga-PSMA-11 accumulation during dynamic PET acquisition. Correlation analysis revealed a moderate, but significant, correlation between PSA levels and the number of lesions detected on (68)Ga-PSMA-11 PET/CT (r = 0.54) and between PSA levels and SUVaverage (r = 0.48) or SUVmax (r = 0.44).
  
  
  CONCLUSIONS
  Ga-PSMA-11 PET/CT demonstrated an overall detection rate of 71.0 % 60 min p.i. of the radiotracer in a mixed patient population with respect to PSA levels and including patients with very low PSA values. Higher PSA values were associated with a higher detection rate. The tracer uptake in PC-recurrence-indicative lesions is increasing during the 60 minutes of dynamic PET acquisition.
authors.affiliation: Clinical Cooperation Unit Nuclear Medicine, German Cancer Research Center (DKFZ), Heidelberg, Germany. christos_saxpe@yahoo.gr.|Medical PET Group-Biological Imaging, Clinical Cooperation Unit Nuclear Medicine, German Cancer Research Center, Im Neuenheimer Feld 280, D-69210, Heidelberg, Germany. christos_saxpe@yahoo.gr.
authors.forename: C
authors.initials: C
authors.lastname: Sachpekidis
authors.affiliation: Division of Radiopharmaceutical Chemistry, German Cancer Research Center (DKFZ), Heidelberg, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Eder
authors.affiliation: Division of Radiopharmaceutical Chemistry, German Cancer Research Center (DKFZ), Heidelberg, Germany.|German Cancer Consortium (DKTK), Heidelberg, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Kopka
authors.affiliation: Division of Nuclear Medicine, University of Heidelberg, Heidelberg, Germany.
authors.forename: W
authors.initials: W
authors.lastname: Mier
authors.affiliation: Department of Urology, University Hospital Heidelberg, Heidelberg, Germany.
authors.forename: B A
authors.initials: BA
authors.lastname: Hadaschik
authors.affiliation: Clinical Cooperation Unit Nuclear Medicine, German Cancer Research Center (DKFZ), Heidelberg, Germany.|German Cancer Consortium (DKTK), Heidelberg, Germany.|Division of Nuclear Medicine, University of Heidelberg, Heidelberg, Germany.
authors.forename: U
authors.initials: U
authors.lastname: Haberkorn
authors.affiliation: Clinical Cooperation Unit Nuclear Medicine, German Cancer Research Center (DKFZ), Heidelberg, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Dimitrakopoulou-Strauss
mesh_terms: D000368:Aged; D000954:Antigens, Surface / Q000378:metabolism; D004492:Edetic Acid / Q000031:analogs & derivatives*; D005709:Gallium Isotopes; D005710:Gallium Radioisotopes; D043425:Glutamate Carboxypeptidase II / Q000378:metabolism; D006801:Humans; D008297:Male; D008875:Middle Aged; D009842:Oligopeptides; D010388:Pelvis / Q000000981:diagnostic imaging; D000072078:Positron Emission Tomography Computed Tomography; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging* / Q000378:metabolism*; D012008:Recurrence; D051598:Whole Body Imaging
chemical_list: D000954:Antigens, Surface; D005709:Gallium Isotopes; D005710:Gallium Radioisotopes; D009842:Oligopeptides; C000718244:gallium 68 PSMA-11; D004492:Edetic Acid; C473848:FOLH1 protein, human; D043425:Glutamate Carboxypeptidase II
keywords: 68Ga-PSMA-ligand PET/CT; PSA; Prostate cancer recurrence; Prostate-specific membrane antigen (PSMA); Two-tissue compartment model