title: Evaluation of BP-ONJ in osteopenic and healthy sheep: comparing ZTE-MRI with µCT.
abstract: OBJECTIVE
  Bisphosphonate-associated osteonecrosis of the jaw (BP-ONJ) is a side effect of antiresorptive treatment that is increasingly prescribed for patients with osteoporosis or malignant diseases with bone metastases. Surgical treatment of BP-ONJ requires adequate pre-operative imaging. To date, CT is the imaging standard in clinical routine; however, defining the extent of the pathological area is difficult and soft tissues are poorly displayed. MRI with zero echo time (ZTE-MRI) to display hard tissues enables a precise display of calcified structures and soft tissues for the delineation of bone necrosis and soft-tissue reactions.
  
  
  METHODS
  BP-ONJ was induced in eight sheep by extraction of two premolars in the left mandible and zoledronate (ZOL) administration. Eight sheep without ZOL administration served as the control group. Four sheep of each main group underwent osteopenia induction via ovariectomy, glucocorticoid administration and a calcium-free diet. After sacrifice, the area of tooth extraction was harvested and scanned with micro-CT (µCT) and ZTE-MRI. Two trained dentists analyzed digital imaging and communications in medicine data sets using three-dimensional imaging software. The periosteal reaction and the remaining extraction sockets were measured.
  
  
  RESULTS
  BP-ONJ was evident, and the remaining extraction sockets were observed in all animals treated with ZOL. Periosteal reactions were more pronounced in animals treated with ZOL, and they appeared broader in ZTE-MRI.
  
  
  CONCLUSIONS
  BP-ONJ lesions in the sheep mandible can be detected using µCT and ZTE-MRI. Although illustration of sequester was more consistent using the µCT, ZTE-MRI was advantageous in evaluation of periosteal reaction.
authors: 1 Department of Oral and Maxillofacial Surgery, University Medical Center Freiburg, Freiburg, Germany.
authors: Pit
authors: P
authors: Voss
authors: 2 Medical Physics, Department of Radiology, University Medical Center Freiburg, Freiburg, Germany.
authors: Ute
authors: U
authors: Ludwig
authors: 1 Department of Oral and Maxillofacial Surgery, University Medical Center Freiburg, Freiburg, Germany.|3 AO Research Institute, Davos, Switzerland.
authors: Philipp
authors: P
authors: Poxleitner
authors: 1 Department of Oral and Maxillofacial Surgery, University Medical Center Freiburg, Freiburg, Germany.
authors: Veronika
authors: V
authors: Bergmaier
authors: 1 Department of Oral and Maxillofacial Surgery, University Medical Center Freiburg, Freiburg, Germany.
authors: Nora
authors: N
authors: El-Shafi
authors: 2 Medical Physics, Department of Radiology, University Medical Center Freiburg, Freiburg, Germany.
authors: Dominik
authors: D
authors: von Elverfeldt
authors: 3 AO Research Institute, Davos, Switzerland.
authors: Vincent
authors: V
authors: Stadelmann
authors: 2 Medical Physics, Department of Radiology, University Medical Center Freiburg, Freiburg, Germany.
authors: Jan-Bernd
authors: JB
authors: Hövener
authors: 1 Department of Oral and Maxillofacial Surgery, University Medical Center Freiburg, Freiburg, Germany.
authors: Tabea
authors: T
authors: Flügge
mesh_terms: D000818:Animals; D059266:Bisphosphonate-Associated Osteonecrosis of the Jaw / Q000175:diagnosis* / Q000000981:diagnostic imaging; D050071:Bone Density Conservation Agents / Q000009:adverse effects; D001851:Bone Diseases, Metabolic / Q000175:diagnosis* / Q000000981:diagnostic imaging; D003907:Dexamethasone / Q000009:adverse effects; D004164:Diphosphonates / Q000009:adverse effects; D004195:Disease Models, Animal; D005260:Female; D005938:Glucocorticoids / Q000009:adverse effects; D007091:Image Processing, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods; D007093:Imidazoles / Q000009:adverse effects; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008336:Mandibular Diseases / Q000175:diagnosis* / Q000000981:diagnostic imaging; D010052:Ovariectomy; D010521:Periosteum / Q000000981:diagnostic imaging / Q000473:pathology; D011897:Random Allocation; D012756:Sheep; D020390:Tooth Socket / Q000000981:diagnostic imaging / Q000473:pathology; D055114:X-Ray Microtomography / Q000379:methods*; D000077211:Zoledronic Acid
chemical_list: D050071:Bone Density Conservation Agents; D004164:Diphosphonates; D005938:Glucocorticoids; D007093:Imidazoles; D000077211:Zoledronic Acid; D003907:Dexamethasone
keywords: animal model; bisphosphonate-associated osteonecrosis of the jaw; magnetic resonance imaging; periosteum; x-ray microtomography