title: Reproducibility of functional volume and activity concentration in 18F-FDG PET/CT of liver metastases in colorectal cancer.
abstract: OBJECTIVE
  Several studies showed potential for monitoring response to systemic therapy in metastatic colorectal cancer patients with (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET). Before (18)F-FDG PET can be implemented for response evaluation the repeatability should be known. This study was performed to assess the magnitude of the changes in standardized uptake value (SUV), volume and total lesion glycolysis (TLG) in colorectal liver metastases and validate the biological basis of (18)F-FDG PET in colorectal liver metastases.
  
  
  METHODS
  Twenty patients scheduled for liver metastasectomy underwent two (18)F-FDG PET scans within 1 week. Bland-Altman analysis was performed to assess repeatability of SUV(max), SUV(mean), volume and TLG. Tumours were delineated using an adaptive threshold method (PET(SBR)) and a semiautomatic fuzzy locally adaptive Bayesian (FLAB) delineation method.
  
  
  RESULTS
  Coefficient of repeatability of SUV(max) and SUV(mean) were ∼39 and ∼31 %, respectively, independent of the delineation method used and image reconstruction parameters. However, repeatability was worse in recently treated patients. The FLAB delineation method improved the repeatability of the volume and TLG measurements compared to PET(SBR), from coefficients of repeatability of over 85 % to 45 % and 57 % for volume and TLG, respectively. Glucose transporter 1 (GLUT1) expression correlated to the SUV(mean). Vascularity (CD34 expression) and tumour hypoxia (carbonic anhydrase IX expression) did not correlate with (18)F-FDG PET parameters.
  
  
  CONCLUSIONS
  In conclusion, repeatability of SUV(mean) and SUV(max) was mainly affected by preceding systemic therapy. The repeatability of tumour volume and TLG could be improved using more advanced and robust delineation approaches such as FLAB, which is recommended when (18)F-FDG PET is utilized for volume or TLG measurements. Improvement of repeatability of PET measurements, for instance by dynamic PET scanning protocols, is probably necessary to effectively use PET for early response monitoring.
authors.affiliation: Department of Medical Oncology, Radboud University Medical Centre, Nijmegen, The Netherlands. l.heijmen@onco.umcn.nl
authors.forename: Linda
authors.initials: L
authors.lastname: Heijmen
authors.forename: Lioe-Fee
authors.initials: LF
authors.lastname: de Geus-Oei
authors.forename: Johannes H W
authors.initials: JH
authors.lastname: de Wilt
authors.forename: Dimitris
authors.initials: D
authors.lastname: Visvikis
authors.forename: Mathieu
authors.initials: M
authors.lastname: Hatt
authors.forename: Eric P
authors.initials: EP
authors.lastname: Visser
authors.forename: Johan
authors.initials: J
authors.lastname: Bussink
authors.forename: Cornelis J A
authors.initials: CJ
authors.lastname: Punt
authors.forename: Wim J G
authors.initials: WJ
authors.lastname: Oyen
authors.forename: Hanneke W M
authors.initials: HW
authors.lastname: van Laarhoven
mesh_terms: D018952:Antigens, CD34 / Q000235:genetics / Q000378:metabolism; D000951:Antigens, Neoplasm / Q000235:genetics / Q000378:metabolism; D001499:Bayes Theorem; D000071231:Carbonic Anhydrase IX; D002256:Carbonic Anhydrases / Q000235:genetics / Q000378:metabolism; D015179:Colorectal Neoplasms / Q000473:pathology*; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics; D015972:Gene Expression Regulation, Neoplastic; D051272:Glucose Transporter Type 1 / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008113:Liver Neoplasms / Q000000981:diagnostic imaging* / Q000556:secondary*; D064847:Multimodal Imaging; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D015203:Reproducibility of Results; D014057:Tomography, X-Ray Computed
chemical_list: D018952:Antigens, CD34; D000951:Antigens, Neoplasm; D051272:Glucose Transporter Type 1; D019275:Radiopharmaceuticals; C495677:SLC2A1 protein, human; D019788:Fluorodeoxyglucose F18; C089226:CA9 protein, human; D000071231:Carbonic Anhydrase IX; D002256:Carbonic Anhydrases