title: Biphasic ⁶⁸Ga-PSMA-HBED-CC-PET/CT in patients with recurrent and high-risk prostate carcinoma.
abstract: OBJECTIVE
  Binding of (68)Ga-PSMA-HBED-CC ((68)Ga-PSMA) at prostate cancer (PC) cells increases over time. A biphasic protocol may help separating benign from tumor lesions. The aim of this study was the retrospective evaluation of a diagnostic incremental value of a dual-time point (biphasic) (68)Ga-PSMA-PET/CT in patients with prostate cancer.
  
  
  METHODS
  Retrospective analysis of 35 consecutive patients (49-78 years, median 71) with newly diagnosed PC (12/35) or recurrence of PC (23/35). PET/CT (Gemini TF16, Philips) was acquired 1 h and 3 h p. i. of 140-392 MBq (300 MBq median) (68)Ga-PSMA, followed by a diagnostic contrast CT. PET findings were correlated with histology or unequivocal CT findings. Semiquantitative PET data (SUVmax, SUV mean) were acquired and target-to-background-ratios (T/B-ratio) were calculated for benign and malign lesions for both time points. Size of lymph nodes (LN) on diagnostic CT was recorded. Statistical analysis was performed for assessment of significant changes of semiquantitative PET-parameters over time and for correlation of size and uptake of lymph nodes.
  
  
  RESULTS
  One hundred and four lesions were evaluated. Sixty lesions were referenced by histology or unequivocal CT findings, including eight (13.3 %) histopathologically benign lymph nodes, 12 (20 %) histopathologically lymph node metastases, 12 (20 %) primary tumors, three (5 %) local recurrences, and 25 (41.7 %) bone metastases. Forty-four lesions were axillary LN with normal CT-appearance. Benign lesions had significantly lower SUVmax and T/B-ratios compared with malignant findings. Malign lesions showed a significant increase of both parameters over time compared to benign findings. There was no correlation between LN size and SUVmax. The sensitivity, specificity, the positive predictive value and negative predictive value of PET/CT regarding pelvic LN was 94 %, 99 %, 89 %, and 99.5 %, respectively.
  
  
  CONCLUSIONS
  In contrast to benign tissues, the uptake of proven tumor lesions increases on (68)Ga-PSMA-PET/CT over time. A biphasic PET-study may lead to a better detection of tumor lesions in unequivocal findings.
authors.affiliation: Department of Nuclear Medicine, University Medical Center Goettingen, Robert-Koch-Str. 40, D-37075, Goettingen, Germany. sahlmann@med.uni-goettingen.de.
authors.forename: Carsten-Oliver
authors.initials: CO
authors.lastname: Sahlmann
authors.affiliation: Department of Nuclear Medicine, University Medical Center Goettingen, Robert-Koch-Str. 40, D-37075, Goettingen, Germany.
authors.forename: Birgit
authors.initials: B
authors.lastname: Meller
authors.affiliation: Department of Nuclear Medicine, University Medical Center Goettingen, Robert-Koch-Str. 40, D-37075, Goettingen, Germany.
authors.forename: Caroline
authors.initials: C
authors.lastname: Bouter
authors.affiliation: Department of Diagnostic and Interventional Radiology, University Medical Center Goettingen, Goettingen, Germany.
authors.forename: Christian Oliver
authors.initials: CO
authors.lastname: Ritter
authors.affiliation: Department of Pathology, University Medical Center Goettingen, Goettingen, Germany.
authors.forename: Philipp
authors.initials: P
authors.lastname: Ströbel
authors.affiliation: Department of Diagnostic and Interventional Radiology, University Medical Center Goettingen, Goettingen, Germany.
authors.forename: Joachim
authors.initials: J
authors.lastname: Lotz
authors.affiliation: Department of Urology, University Medical Center Goettingen, Goettingen, Germany.
authors.forename: Lutz
authors.initials: L
authors.lastname: Trojan
authors.affiliation: Department of Nuclear Medicine, University Medical Center Goettingen, Robert-Koch-Str. 40, D-37075, Goettingen, Germany.
authors.forename: Johannes
authors.initials: J
authors.lastname: Meller
authors.affiliation: Department of Urology, University Medical Center Goettingen, Goettingen, Germany.
authors.forename: Sameh
authors.initials: S
authors.lastname: Hijazi
mesh_terms: D000328:Adult; D000368:Aged; D002277:Carcinoma / Q000000981:diagnostic imaging*; D004492:Edetic Acid / Q000031:analogs & derivatives; D005709:Gallium Isotopes; D005710:Gallium Radioisotopes; D006801:Humans; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local; D009842:Oligopeptides; D009942:Organometallic Compounds; D000072078:Positron Emission Tomography Computed Tomography; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging*; D019275:Radiopharmaceuticals
chemical_list: D005709:Gallium Isotopes; D005710:Gallium Radioisotopes; D009842:Oligopeptides; D009942:Organometallic Compounds; D019275:Radiopharmaceuticals; C000718244:gallium 68 PSMA-11; D004492:Edetic Acid
keywords: 68Ga; HBED; PET; PET/CT; PSMA; Prostate carcinoma