title: Magnetic resonance imaging of an equine fracture model containing stainless steel metal implants.
abstract: BACKGROUND
  Post operative imaging in subjects with orthopaedic implants is challenging across all modalities. Magnetic resonance imaging (MRI) is preferred to assess human post operative musculoskeletal complications, as soft tissue and bones are evaluated without using ionising radiation. However, with conventional MRI pulse sequences, metal creates susceptibility artefact that distorts anatomy. Assessment of the post operative equine patient is arguably more challenging due to the volume of metal present, and MRI is often not performed in horses with implants. Novel pulse sequences such as multiacquisition variable resonance image combination (MAVRIC) now provide improved visibility in the vicinity of surgical-grade implants and offer an option for imaging horses with metal implants.
  
  
  OBJECTIVE
  To compare conspicuity of regional anatomy in an equine fracture-repair model using MAVRIC, narrow receiver bandwidth (NBW) fast spin echo (FSE), and wide receiver bandwidth (WBW) FSE sequences.
  
  
  METHODS
  Nonrandomised in vitro experiment.
  
  
  METHODS
  MAVRIC, NBW FSE and WBW FSE were performed on 9 cadaveric distal limbs with fractures and stainless steel implants in the third metacarpal bone and proximal phalanx. Objective measures of artefact reduction were performed by calculating the total artefact area in each transverse image as a percentage of the total anatomic area. The number of transverse images in which fracture lines were visible was tabulated for each sequence. Regional soft tissue conspicuity was assessed subjectively.
  
  
  RESULTS
  Overall anatomic delineation was improved using MAVRIC compared with NBW FSE; delineation of structures closest to the metal implants was improved using MAVRIC compared with WBW FSE and NBW FSE. Total artefact area was the highest for NBW FSE and lowest for MAVRIC; the total number of transverse slices with a visible fracture line was highest in MAVRIC and lowest in NBW FSE.
  
  
  CONCLUSIONS
  MAVRIC and WBW FSE are feasible additions to minimise artefact around implants.
authors: MRI Laboratory, Hospital for Special Surgery, New York, USA.
authors: S L
authors: SL
authors: Pownder
authors: MRI Laboratory, Hospital for Special Surgery, New York, USA.
authors: M F
authors: MF
authors: Koff
authors: MRI Laboratory, Hospital for Special Surgery, New York, USA.
authors: P H
authors: PH
authors: Shah
authors: Department of Clinical Sciences, Cornell University College of Veterinary Medicine, Ithaca, New York, USA.
authors: L A
authors: LA
authors: Fortier
authors: MRI Laboratory, Hospital for Special Surgery, New York, USA.
authors: H G
authors: HG
authors: Potter
mesh_terms: D000818:Animals; D002102:Cadaver; D050723:Fractures, Bone / Q000000981:diagnostic imaging / Q000662:veterinary*; D006736:Horses / Q000293:injuries*; D016268:Internal Fixators / Q000662:veterinary*; D008279:Magnetic Resonance Imaging / Q000662:veterinary*; D013193:Stainless Steel
chemical_list: D013193:Stainless Steel
keywords: fracture repair; horse; magnetic resonance imaging; multiacquisition variable resonance image combination (MAVRIC); susceptibility artefact