title: The ability of 18F-choline PET/CT to identify local recurrence of prostate cancer.
abstract: OBJECTIVE
  To determine when 18F-choline PET/CT can truly identify local recurrence of prostate cancer.
  
  
  METHODS
  1031 patients from 3 European centers underwent (18)F-choline PET/CT (FCH PET/CT) for recurrent disease; 131 subjects (12.7%) showed a positive FCH uptake in the prostatic gland or prostatic fossa. Median age was 72 years (range 48-87 years), and the median PSA level at the time of FCH PET/CT scan was 4.41 ng/mL (0.22-18.13 ng/mL). 45 patients (34.4%) had a Gleason score (GS) >7, and the residual subjects had a GS ≤ 7. The assessment of true or false-positive FCH PET/CT findings was made by magnetic resonance imaging (n = 34) and/or biopsy in 75/131 cases. A χ (2) test and a Z Kolmogorov-Smirnov test were used to assess the correlation between clinical variables (age, PSA, GS, type of therapy) and FCH PET/CT findings.
  
  
  RESULTS
  FCH PET/CT resulted truly positive (TP) for recurrent disease in the prostatic gland/fossa in 59/75 patients (79%) and falsely positive (FP) in 16 subjects (21%). The median value of PSA at the time of FCH PET/CT scan was higher in TP as compared to FP, although not statistically significant (4.76 vs. 3.04 ng/mL p > 0.05). Similarly, median age, GS categories, and the type of therapy were similar between the two groups (p > 0.05). However, when matching GS categories and PSA values, we found that the number of patients with TP findings were higher in the case of a PSA > 2 ng/mL, independently from the GS (ranging between 74% and 92%). Conversely, FP rate ranged between 50% and 65% in patients with a PSA ≤ 2 ng/mL, especially in the case of GS ≤ 7, whereas FP was around 25% in those with a GS >7 and PSA > 2 ng/mL.
  
  
  CONCLUSIONS
  FCH PET/CT has a limited role in evaluation of prostatic gland/fossa recurrence, due to the physiological biodistribution of the radiopharmaceutical agent. However, in 70-90% of patients with a PSA >2 ng/mL, independently from GS, a focal FCH uptake is compatible with a true local recurrence.
authors.affiliation: Radiotherapy and Nuclear Medicine Unit, Veneto Institute of Oncology IOV - IRCCS, Via Gattamelata, 64, 35128, Padua, Italy. laura.evangelista@ioveneto.it.
authors.forename: Laura
authors.initials: L
authors.lastname: Evangelista
authors.affiliation: Nuclear Medicine Unit, IRCCS National Cancer Institute (CRO), Aviano, PN, Italy.
authors.forename: Marino
authors.initials: M
authors.lastname: Cimitan
authors.affiliation: Nuclear Medicine Research Department, IASON, Graz, Austria.
authors.forename: Marina
authors.initials: M
authors.lastname: Hodolič
authors.affiliation: Nuclear Medicine Unit, IRCCS National Cancer Institute (CRO), Aviano, PN, Italy.
authors.forename: Tanja
authors.initials: T
authors.lastname: Baseric
authors.affiliation: Nuclear Medicine Department, University Medical Center Ljubljana, Ljubljana, Slovenia.
authors.forename: Jure
authors.initials: J
authors.lastname: Fettich
authors.affiliation: Nuclear Medicine Unit, IRCCS National Cancer Institute (CRO), Aviano, PN, Italy.
authors.forename: Eugenio
authors.initials: E
authors.lastname: Borsatti
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002794:Choline / Q000031:analogs & derivatives*; D006801:Humans; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D009364:Neoplasm Recurrence, Local / Q000175:diagnosis*; D049268:Positron-Emission Tomography; D011467:Prostate / Q000000981:diagnostic imaging; D011471:Prostatic Neoplasms / Q000175:diagnosis*; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed
chemical_list: D019275:Radiopharmaceuticals; C516370:fluoromethylcholine; D002794:Choline
keywords: 18F-choline PET/CT; False positive; Prostate cancer recurrence; Salvage treatments; True positive