title: Indirect MR-arthrography in osteochondral autograft and crushed bone graft with a collagen membrane--correlation with histology.
abstract: OBJECTIVE
  To analyze the spectrum of findings in indirect MR-arthrography following osteochondral autograft transfer system (OATS) and crushed bone graft using a magnetic resonance imaging (MRI) scoring and grading system in relation to histology as the standard of reference.
  
  
  METHODS
  Iatrogenic lesions were set at ovine condylar facets (n=6/group), treated with OATS or crushed bone graft. 1.5 T MRI was performed 6 months after surgery using PD-weighted (w fat saturated (fs) fast spin echo (FSE), T1-w 2D, and 3D fs gradient echo (GE) sequences 30 min. after i.v. Gd-DTPA administration and passive joint exercise. The repair tissue was evaluated by two independent radiologists. The MR findings were compared to histology.
  
  
  RESULTS
  In all cases, MRI and histologic grading correlated well and showed significant superior repair in OATS at 6 months (p<0.05), reproducing the original articular contour and a good subchondral restoration. FsT1-w3DGE proved most appropriate identifying characteristic post-operative findings: the OATS group demonstrated bone marrow edema at the donor site and the graft/host interface showed significant enhancement in indirect MR-arthrography, indicating fibrocartilage. After crushed bone graft, we found an irregular structure and significant contrast uptake, consistent with remnants of bone grafts surrounded by inflammatory tissue.
  
  
  CONCLUSIONS
  Indirect MR-arthrography is an accurate, non-invasive monitoring tool following OATS and crushed bone graft as the MRI scoring and grading system allows a reliable evaluation of normal and pathological osteochondral repair with a high histologic correlation.
authors.affiliation: Klinik für Strahlenheilkunde, Charité, Campus Virchow-Klinikum, Humboldt-University, Berlin, Germany. florian.streitparth@charite.de
authors.forename: F
authors.initials: F
authors.lastname: Streitparth
authors.forename: P
authors.initials: P
authors.lastname: Schöttle
authors.forename: H
authors.initials: H
authors.lastname: Schell
authors.forename: L
authors.initials: L
authors.lastname: Lehmkuhl
authors.forename: T
authors.initials: T
authors.lastname: Madej
authors.forename: G
authors.initials: G
authors.lastname: Wieners
authors.forename: G N
authors.initials: GN
authors.lastname: Duda
authors.forename: R J
authors.initials: RJ
authors.lastname: Schröder
mesh_terms: D000818:Animals; D018786:Bone Substitutes / Q000627:therapeutic use*; D016025:Bone Transplantation / Q000295:instrumentation* / Q000379:methods; D002358:Cartilage, Articular / Q000293:injuries / Q000473:pathology / Q000601:surgery*; D003094:Collagen / Q000627:therapeutic use*; D050724:Fractures, Cartilage / Q000473:pathology* / Q000601:surgery*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008567:Membranes, Artificial; D012756:Sheep; D013223:Statistics as Topic; D016896:Treatment Outcome
chemical_list: D018786:Bone Substitutes; D008567:Membranes, Artificial; D003094:Collagen