title: Quantification of 18F-Fluoride Kinetics: Evaluation of Simplified Methods.
abstract: (18)F-fluoride PET is a promising noninvasive method for measuring bone metabolism and bone blood flow. The purpose of this study was to assess the performance of various clinically useful simplified methods by comparing them with full kinetic analysis. In addition, the validity of deriving bone blood flow from K1 of (18)F-fluoride was investigated using (15)O-H2O as a reference.
  
  
  METHODS
  Twenty-two adults (mean age ± SD, 44.8 ± 25.2 y), including 16 patients scheduled for bone surgery and 6 healthy volunteers, were studied. All patients underwent dynamic (15)O-H2O and (18)F-fluoride scans before surgery. Ten of these patients had serial PET measurements before and at 2 time points after local bone surgery. During all PET scans, arterial blood was monitored continuously. (18)F-fluoride data were analyzed using nonlinear regression (NLR) and several simplified methods (Patlak and standardized uptake value [SUV]). SUV was evaluated for different time intervals after injection and after normalizing to body weight, lean body mass, and body surface area, and simplified measurements were compared with NLR results. In addition, changes in SUV and Patlak-derived fluoride influx rate (Ki) after surgery were compared with corresponding changes in NLR-derived Ki. Finally, (18)F-fluoride K1 was compared with bone blood flow derived from (15)O-H2O data, using the standard single-tissue-compartment model.
  
  
  RESULTS
  K1 of (18)F-fluoride correlated with measured blood flow, but the correlation coefficient was relatively low (r = 0.35, P < 0.001). NLR resulted in a mean Ki of 0.0160 ± 0.0122, whereas Patlak analysis, for the interval 10-60 min after injection, resulted in an almost-identical mean Ki of 0.0161 ± 0.0117. The Patlak-derived Ki, for 10-60 min after injection, showed a high correlation with the NLR-derived Ki (r = 0.976). The highest correlation between Ki and lean body mass-normalized SUV was found for the interval 50-60 min (r = 0.958). Finally, changes in SUV correlated significantly with those in Ki (r = 0.97).
  
  
  CONCLUSIONS
  The present data support the use of both Patlak and SUV for assessing fluoride kinetics in humans. However, (18)F-fluoride PET has only limited accuracy in monitoring bone blood flow.
authors.affiliation: Department of Radiology and Nuclear Medicine, MOVE Research Institute, VU University Medical Center, Amsterdam, The Netherlands p.raijmakers@vumc.nl.
authors.forename: Pieter
authors.initials: P
authors.lastname: Raijmakers
authors.affiliation: Department Orthopaedic Surgery, Alkmaar Medical Center, Alkmaar, The Netherlands.
authors.forename: Olivier P P
authors.initials: OP
authors.lastname: Temmerman
authors.affiliation: Department of Oral and Maxillofacial Surgery, Haga Hospital, The Hague, The Netherlands.
authors.forename: Carrol P
authors.initials: CP
authors.lastname: Saridin
authors.affiliation: Department Orthopaedic Surgery, Atrium Hospital, Heerlen, The Netherlands; and.
authors.forename: Ide C
authors.initials: IC
authors.lastname: Heyligers
authors.affiliation: Department of Oral and Maxillofacial Surgery and Oral Pathology, Amsterdam Medical Center and Academic Center of Dentistry, Amsterdam, The Netherlands.
authors.forename: Alfred G
authors.initials: AG
authors.lastname: Becking
authors.affiliation: Department of Radiology and Nuclear Medicine, MOVE Research Institute, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Arthur
authors.initials: A
authors.lastname: van Lingen
authors.affiliation: Department of Radiology and Nuclear Medicine, MOVE Research Institute, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Adriaan A
authors.initials: AA
authors.lastname: Lammertsma
mesh_terms: D000328:Adult; D001692:Biological Transport; D001842:Bone and Bones / Q000098:blood supply / Q000000981:diagnostic imaging; D005459:Fluorides / Q000138:chemical synthesis / Q000378:metabolism*; D005462:Fluorine Radioisotopes; D006801:Humans; D007700:Kinetics; D008954:Models, Biological; D011877:Radionuclide Imaging
chemical_list: D005462:Fluorine Radioisotopes; D005459:Fluorides
keywords: 18F-fluoride PET; SUV; kinetic modeling; quantification