title: Comparison of68Ga-labelled PSMA-11 and11C-choline in the detection of prostate cancer metastases by PET/CT.
abstract: OBJECTIVE
  Prostate-specific membrane antigen (PSMA) is expressed ubiquitously on the membrane of most prostate tumors and its metastasis. While PET/CT using11C-choline was considered as the gold standard in the staging of prostate cancer, PET with radiolabelled PSMA ligands was introduced into the clinic in recent years. Our aim was to compare the PSMA ligand68Ga-PSMA-11 with11C-choline in patients with primary and recurrent prostate cancer.
  
  
  METHODS
  123 patients underwent a whole-body PET/CT examination using68Ga-PSMA-11 and11C-choline. Suspicious lesions were evaluated visually and semiquantitatively (SUVavg). Out of these, 103 suffered from a confirmed biochemical relapse after prostatectomy and/or radiotherapy (mean PSA level of 4.5 ng/ml), while 20 patients underwent primary staging.
  
  
  RESULTS
  In 67 patients with biochemical relapse, we detected 458 lymph nodes suspicious for metastasis. PET using68Ga-PSMA-11 showed a significantly higher uptake and detection rate than11C-choline PET. Also68Ga-PSMA-11 PET identified significantly more patients with suspicious lymph nodes as well as affected lymph nodes regions especially at low PSA levels. Bone lesions suspicious for prostate cancer metastasis were revealed in 36 patients' biochemical relapse. Significantly more bone lesions were detected by68Ga-PSMA-11, but only 3 patients had only PSMA-positive bone lesions. Nevertheless, we detected also 29 suspicious lymph nodes and 8 bone lesions, which were only positive as per11C-choline PET. These findings led to crucial differences in the TNM classification and the identification of oligometastatic patients. In the patients who underwent initial staging, all primary tumors showed uptake of both tracers. Although significantly more suspicious lymph nodes and bone lesions were identified, only 2 patients presented with bone lesions only detected by68Ga-PSMA-11 PET.
  
  
  CONCLUSIONS
  Thus, PET using68Ga-PSMA-11 showed a higher detection rate than11C-choline PET for lymph nodes as well as bone lesions. However, we found lymph nodes and bone lesions which were not concordant applying both tracers.
authors.affiliation: Department of Nuclear Medicine and Clinical Molecular Imaging, Eberhard Karls University, Otfried-Müller-Straße 14, 72076, Tübingen, Germany.|Department of Preclinical Imaging and Radiopharmacy, Eberhard Karls University, Röntgenweg 13, 72076, Tübingen, Germany.
authors.forename: Johannes
authors.initials: J
authors.lastname: Schwenck
authors.affiliation: Department of Diagnostic and Interventional Radiology, Eberhard Karls University, Hoppe-Seyler-Straße 3, 72076, Tübingen, Germany.
authors.forename: Hansjoerg
authors.initials: H
authors.lastname: Rempp
authors.affiliation: Department of Preclinical Imaging and Radiopharmacy, Eberhard Karls University, Röntgenweg 13, 72076, Tübingen, Germany.
authors.forename: Gerald
authors.initials: G
authors.lastname: Reischl
authors.affiliation: Department of Urology, Eberhard Karls University, Hoppe-Seyler-Straße 3, 72076, Tübingen, Germany.
authors.forename: Stephan
authors.initials: S
authors.lastname: Kruck
authors.affiliation: Department of Urology, Eberhard Karls University, Hoppe-Seyler-Straße 3, 72076, Tübingen, Germany.
authors.forename: Arnulf
authors.initials: A
authors.lastname: Stenzl
authors.affiliation: Department of Diagnostic and Interventional Radiology, Eberhard Karls University, Hoppe-Seyler-Straße 3, 72076, Tübingen, Germany.
authors.forename: Konstantin
authors.initials: K
authors.lastname: Nikolaou
authors.affiliation: Department of Diagnostic and Interventional Radiology, Eberhard Karls University, Hoppe-Seyler-Straße 3, 72076, Tübingen, Germany.
authors.forename: Christina
authors.initials: C
authors.lastname: Pfannenberg
authors.affiliation: Department of Nuclear Medicine and Clinical Molecular Imaging, Eberhard Karls University, Otfried-Müller-Straße 14, 72076, Tübingen, Germany. christian.lafougere@med.uni-tuebingen.de.|German Cancer Consortium, German Cancer Research Center Partner Site, Heidelberg, Germany. christian.lafougere@med.uni-tuebingen.de.
authors.forename: Christian
authors.initials: C
authors.lastname: la Fougère
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001859:Bone Neoplasms / Q000000981:diagnostic imaging* / Q000556:secondary*; D002794:Choline / Q000031:analogs & derivatives*; D004492:Edetic Acid / Q000031:analogs & derivatives; D005709:Gallium Isotopes; D005710:Gallium Radioisotopes; D006801:Humans; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D009842:Oligopeptides; D009942:Organometallic Compounds; D000072078:Positron Emission Tomography Computed Tomography / Q000379:methods*; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging*; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D000071036:Sentinel Lymph Node / Q000000981:diagnostic imaging; D051598:Whole Body Imaging
chemical_list: D005709:Gallium Isotopes; D005710:Gallium Radioisotopes; D009842:Oligopeptides; D009942:Organometallic Compounds; D019275:Radiopharmaceuticals; C000718244:gallium 68 PSMA-11; C447081:methyl carbon-11 choline; D004492:Edetic Acid; D002794:Choline
keywords: Choline; PET/CT; PSMA; Prostate cancer