title: Application of F-18-sodium fluoride (NaF) dynamic PET-CT (dPET-CT) for defect healing: a comparison of biomaterials in an experimental osteoporotic rat model.
abstract: BACKGROUND
  The aim of the current study was to measure and compare the effect of various biomaterials for the healing of osteoporotic bone defects in the rat femur using 18F-sodium fluoride dPET-CT.
  
  
  METHODS
  Osteoporosis was induced by ovariectomy and a calcium-restricted diet. After 3 months, rats were operated on to create a 4-mm wedge-shaped defect in the distal metaphyseal femur. Bone substitution materials of calcium phosphate cement (CPC), composites of collagen and silica, and iron foams with interconnecting pores were inserted. Strontium or bisphosphonate, which are well known for having positive effects in osteoporosis treatment, were added into the materials. Eighteen weeks after osteoporosis induction and 6 weeks following femoral surgery, dPET-CT studies scan were performed with 18F-Sodium Fluoride. Standardized uptake values (SUVs) and a 2-tissue compartmental learning-machine model (K1-k4, vessel density [VB], influx [ki]) were used for quantitative analysis.
  
  
  RESULTS
  k3, reflecting the formation of fluoroapatite, revealed a statistically significant increase at the biomaterial-bone interface due to the Sr release from strontium-modified calcium phosphate cement (SrCPC) compared to CPC, which demonstrated enhanced new bone formation. In addition, k3 as measured in the porous scaffold silica/collagen xerogel (Sc-B30), showed a significant increase based on Wilcoxon rank-sum test (p<0.05) as compared with monolithic silica/collagen xerogel (B30) in the defect region. Furthermore, ki, reflecting the net plasma clearance of tracer to bone mineral measured in the iron foam with coating of the bisphosphonate zoledronic acid (Fe-BP), was enhanced as compared with plain iron foam (Fe) in the defect region.
  
  
  CONCLUSIONS
  k3 was the most significant parameter for the characterization of healing processes and revealed the best differentiation between the 2 different biomaterials. PET scanning using 18F-sodium fluoride seems to be a sensitive and useful method for evaluation of bone healing after replacement with these biomaterials.
authors.affiliation: Clinical Cooperation Unit Nuclear Medicine, German Cancer Research Center, Heidelberg, Germany.
authors.forename: Caixia
authors.initials: C
authors.lastname: Cheng
authors.affiliation: Department of Trauma Surgery, University Hospital Giessen-Marburg GmbH, Giessen, Germany.
authors.forename: Volker
authors.initials: V
authors.lastname: Alt
authors.affiliation: Clinical Cooperation Unit Nuclear Medicine, German Cancer Research Center, Heidelberg, Germany.
authors.forename: Leyun
authors.initials: L
authors.lastname: Pan
authors.affiliation: Department of Trauma Surgery, University Hospital Giessen-Marburg GmbH, Giessen, Germany.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Thormann
authors.affiliation: Department of Trauma Surgery, University Hospital Giessen-Marburg GmbH, Giessen, Germany.
authors.forename: Reinhard
authors.initials: R
authors.lastname: Schnettler
authors.affiliation: Clinical Cooperation Unit Nuclear Medicine, German Cancer Research Center, Heidelberg, Germany.
authors.forename: Ludwig G
authors.initials: LG
authors.lastname: Strauss
authors.affiliation: Max-Bergmann-Center of Biomaterials, Institute of Materials Science, Technische Universität Dresden, Dresden, Germany.
authors.forename: Sascha
authors.initials: S
authors.lastname: Heinemann
authors.affiliation: Technische Universität Dresden, Centre for Translational Bone, Joint and Soft Tissue Research, Medical Faculty and University Hospital Carl Gustav Carus, Dresden, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Schumacher
authors.affiliation: Technische Universität Dresden, Centre for Translational Bone, Joint and Soft Tissue Research, Medical Faculty and University Hospital Carl Gustav Carus, Dresden, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Gelinsky
authors.affiliation: InnoTERE GmbH, Radebeul, Germany.
authors.forename: Berthold
authors.initials: B
authors.lastname: Nies
authors.affiliation: Clinical Cooperation Unit Nuclear Medicine, German Cancer Research Center, heidelberg, Germany.
authors.forename: Antonia
authors.initials: A
authors.lastname: Dimitrakopoulou-Strauss
mesh_terms: D000818:Animals; D001672:Biocompatible Materials; D004195:Disease Models, Animal; D005260:Female; D064847:Multimodal Imaging; D010024:Osteoporosis / Q000473:pathology*; D049268:Positron-Emission Tomography; D051381:Rats; D017207:Rats, Sprague-Dawley; D012969:Sodium Fluoride / Q000008:administration & dosage*; D014057:Tomography, X-Ray Computed
chemical_list: D001672:Biocompatible Materials; D012969:Sodium Fluoride