title: Repeatability of Quantitative 18F-Fluoromethylcholine PET/CT Studies in Prostate Cancer.
abstract: Repeatable quantification is essential when using (18)F-fluoromethylcholine PET/CT to monitor treatment response in prostate cancer. It has been shown that SUV normalized to the area under the blood activity concentration curve (SUVAUC) provides a better correlation with full kinetic analysis than does standard SUV. However, the precision of SUVAUC is not known yet. The purpose of this study was to assess the repeatability of various semiquantitative (18)F-fluoromethylcholine parameters in prostate cancer.
  
  
  METHODS
  Twelve patients (mean age ± SD, 64 ± 8 y) with metastasized prostate cancer underwent two sets of (18)F-fluoromethylcholine PET/CT scans, on consecutive days. Each set consisted of a 30-min dynamic PET/CT scan of the chest after intravenous administration of 200 MBq of (18)F-fluoromethylcholine, followed by a whole-body PET/CT scan at 40 min. The dynamic scan was used to derive the area under the blood activity concentration curve. Lesion uptake was derived from the whole-body scan using various types of volumes of interest: maximum, peak, and mean. Each of these parameters was normalized to injected activity per body weight, area under the blood activity concentration curve, and blood concentration itself at 40 min, resulting in several types of SUVs: SUV, SUVAUC, and SUVTBR The test-retest repeatability of these metrics, as well as metabolic tumor volume (MTV) and total uptake of choline in the lesion, were studied. The level of agreement between test-retest data and reliability was assessed using Bland-Altman plots, repeatability coefficients, and intraclass correlation coefficients (ICCs).
  
  
  RESULTS
  A total of 67 choline-avid metastases were identified: 44 bone lesions and 23 lymph node lesions. In the case of SUVmax, the repeatability coefficients for SUV, SUVAUC, and SUVTBR were 26% (ICC, 0.95), 31% (ICC, 0.95), and 46% (ICC, 0.89), respectively. Similar values were obtained for SUVpeak and SUVmean The repeatability of SUVAUC was comparable to that of SUVmax, SUVpeak, and SUVmean. Tissue type and tumor localization did not affect repeatability. An MTV of less than 4.2 cm(3) had larger variability than larger volumes (repeatability coefficient, 45% vs. 29%; P = 0.048). The repeatability coefficient did not significantly differ between lesions with SUVpeak above or below the median value of 8.3 (19% vs. 28%; P = 0.264).
  
  
  CONCLUSIONS
  The repeatability of SUVAUC was comparable to that of standard SUV. The repeatability coefficients of various semiquantitative (18)F-fluoromethylcholine parameters (SUV, MTV, and total uptake in the lesion) were approximately 35%. Larger differences are likely to represent treatment effects.
authors.affiliation: Department of Radiology and Nuclear Medicine, VU University Medical Center, Amsterdam, The Netherlands d.oprea-lager@vumc.nl.
authors.forename: Daniela E
authors.initials: DE
authors.lastname: Oprea-Lager
authors.affiliation: Department of Radiology and Nuclear Medicine, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Gem
authors.initials: G
authors.lastname: Kramer
authors.affiliation: Department of Epidemiology and Biostatistics, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Peter M
authors.initials: PM
authors.lastname: van de Ven
authors.affiliation: Department of Medical Oncology, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Alfons J M
authors.initials: AJ
authors.lastname: van den Eertwegh
authors.affiliation: Department of Urology, VU University Medical Center, Amsterdam, The Netherlands; and.
authors.forename: Reindert J A
authors.initials: RJ
authors.lastname: van Moorselaar
authors.affiliation: Department of Anesthesiology, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Patrick
authors.initials: P
authors.lastname: Schober
authors.affiliation: Department of Radiology and Nuclear Medicine, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Otto S
authors.initials: OS
authors.lastname: Hoekstra
authors.affiliation: Department of Radiology and Nuclear Medicine, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Adriaan A
authors.initials: AA
authors.lastname: Lammertsma
authors.affiliation: Department of Radiology and Nuclear Medicine, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Ronald
authors.initials: R
authors.lastname: Boellaard
mesh_terms: D000368:Aged; D002794:Choline / Q000031:analogs & derivatives*; D006801:Humans; D008297:Male; D008875:Middle Aged; D000072078:Positron Emission Tomography Computed Tomography / Q000379:methods*; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging*; D015203:Reproducibility of Results
chemical_list: C516370:fluoromethylcholine; D002794:Choline
keywords: choline; positron emission tomography (PET); prostate cancer; repeatability; standardized uptake value (SUV)