title: Comparison of NaF and FDG PET/CT for assessment of treatment response in castration-resistant prostate cancers with osseous metastases.
abstract: BACKGROUND
  Assessment of skeletal metastases' response to therapy is a highly relevant but unresolved clinical problem. The main goal of this work was to compare pharmacodynamic responses to therapy assessed with positron emission tomography-computed tomography (PET/CT) using fluorine-18 sodium fluoride (NaF) and fluorine-18 fluorodeoxyglucose (FDG) as the tracers.
  
  
  METHODS
  Patients with prostate cancer with known osseous metastases were treated with zibotentan (ZD4054) and imaged with combined dynamic NaF/FDG PET/CT before therapy (baseline), after 4 weeks of therapy (week 4), and after 2 weeks of treatment break (week 6). Kinetic analysis allowed comparison of the voxel-based tracer uptake rate parameter Ki, the vasculature parameters K1 (measuring perfusion/permeability) and Vb (measuring vasculature fraction in the tissue), and the standardized uptake values (SUVs).
  
  
  RESULTS
  Correlations were high for the NaF and FDG peak uptake parameters (Ki and SUV correlations ranged from 0.57 to 0.88) and for vasculature parameters (K1 and Vb correlations ranged from 0.61 to 0.81). Correlation was low between the NaF and FDG week 4 Ki responses (ρ = 0.35; P = .084) but was higher for NaF and FDG week 6 Ki responses (ρ = 0.72; P < .0001). Correlations for vasculature responses were always low (ρ < 0.35). NaF and FDG uptakes in the osseous metastases were spatially dislocated, with overlap in the range from 0% to 80%.
  
  
  CONCLUSIONS
  This study found that late NaF and FDG uptake responses are consistently correlated but that earlier uptake responses and all vasculature responses can be unrelated. This study also confirmed that FDG and NaF uptakes are spatially dislocated. Although treatment responses assessed with NaF and FDG may be correlated, using both tracers provides additional information.
authors.affiliation: Jozef Stefan Institute, Ljubljana, Slovenia; Department of Medical Physics, University of Wisconsin-Madison, Madison, WI; Centre of Excellence for Biosensors, Instrumentation and Process Control (COBIK), Ajdovscina, Slovenia. Electronic address: urban.simoncic@ijs.si.
authors.forename: Urban
authors.initials: U
authors.lastname: Simoncic
authors.affiliation: Department of Radiology, University of Wisconsin-Madison, Madison, WI; University of Wisconsin Carbone Cancer Center, University of Wisconsin-Madison, Madison, WI.
authors.forename: Scott
authors.initials: S
authors.lastname: Perlman
authors.affiliation: Genitourinary Oncology Research Program, University of Wisconsin Carbone Cancer Center, University of Wisconsin-Madison, Madison, WI; University of Wisconsin Carbone Cancer Center, University of Wisconsin-Madison, Madison, WI.
authors.forename: Glenn
authors.initials: G
authors.lastname: Liu
authors.affiliation: University of Wisconsin Carbone Cancer Center, University of Wisconsin-Madison, Madison, WI.
authors.forename: Mary Jane
authors.initials: MJ
authors.lastname: Staab
authors.affiliation: University of Wisconsin Carbone Cancer Center, University of Wisconsin-Madison, Madison, WI.
authors.forename: Jane Elizabeth
authors.initials: JE
authors.lastname: Straus
authors.affiliation: Jozef Stefan Institute, Ljubljana, Slovenia; Department of Medical Physics, University of Wisconsin-Madison, Madison, WI; Department of Radiology, University of Wisconsin-Madison, Madison, WI; Centre of Excellence for Biosensors, Instrumentation and Process Control (COBIK), Ajdovscina, Slovenia; University of Wisconsin Carbone Cancer Center, University of Wisconsin-Madison, Madison, WI.
authors.forename: Robert
authors.initials: R
authors.lastname: Jeraj
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001859:Bone Neoplasms / Q000188:drug therapy / Q000556:secondary*; D017326:Clinical Trials, Phase III as Topic; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography; D064129:Prostatic Neoplasms, Castration-Resistant / Q000188:drug therapy / Q000473:pathology*; D011759:Pyrrolidines / Q000008:administration & dosage; D012969:Sodium Fluoride; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome
chemical_list: D011759:Pyrrolidines; C511404:ZD4054; D019788:Fluorodeoxyglucose F18; D012969:Sodium Fluoride
keywords: Dual-tracer PET imaging; Kinetic analysis; Skeletal metastases; Therapy response assessment; Zibotentan