title: Perfusion MRI in hips with metal-on-metal and metal-on-polyethylene total hip arthroplasty: A pilot study.
abstract: OBJECTIVE
  Hips with metal-on-metal total hip arthroplasty (MoM THA) have a high rate of adverse local tissue reactions (ALTR), often associated with hypersensitivity reactions. Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) measures tissue perfusion with the parameter Ktrans (volume transfer constant of contrast agent). Our purpose was 1) to evaluate the feasibility of DCE-MRI in patients with THA and 2) to compare DCE-MRI in patients with MoM bearings with metal-on-polyethylene (MoP) bearings, hypothesising that the perfusion index Ktrans in hips with MoM THA is higher than in hips with MoP THA.
  
  
  METHODS
  In this pilot study, 16 patients with primary THA were recruited (eight MoM, eight MoP). DCE-MRI of the hip was performed at 1.5 Tesla (T). For each patient, Ktrans was computed voxel-by-voxel in all tissue lateral to the bladder. The mean Ktrans for all voxels was then calculated. These values were compared with respect to implant type and gender, and further correlated with clinical parameters.
  
  
  RESULTS
  There was no significant difference between the two bearing types with both genders combined. However, dividing patients by THA bearing and gender, women with MoM bearings had the highest Ktrans values, exceeding those of women with MoP bearings (0.067 min(-1) versus 0.053 min(-1); p-value < 0.05) and men with MoM bearings (0.067 min(-1) versus 0.034 min(-1); p-value < 0.001). Considering only the men, patients with MoM bearings had lower Ktrans than those with MoP bearings (0.034 min(-1) versus 0.046 min(-1); p < 0.05).
  
  
  CONCLUSIONS
  DCE-MRI is feasible to perform in tissues surrounding THA. Females with MoM THA show high Ktrans values in DCE-MRI, suggesting altered tissue perfusion kinematics which may reflect relatively greater inflammation.Cite this article: Dr P. E. Beaule. Perfusion MRI in hips with metal-on-metal and metal-on-polyethylene total hip arthroplasty: A pilot stud. Bone Joint Res 2016;5:73-79. DOI: 10.1302/2046-3758.53.2000572.
authors.affiliation: Universität für Orthopädische Chirurgie und Traumatologie, Freiburgstrasse 4, 3010 Bern, Switzerland.
authors.forename: H
authors.initials: H
authors.lastname: Anwander
authors.affiliation: The Ottawa Hospital, University of Ottawa, 501 Smyth Road, Ottawa, ON, Canada.
authors.forename: G O
authors.initials: GO
authors.lastname: Cron
authors.affiliation: The Ottawa Hospital, University of Ottawa, 501 Smyth Road, Ottawa, ON, Canada.
authors.forename: K
authors.initials: K
authors.lastname: Rakhra
authors.affiliation: The Ottawa Hospital, University of Ottawa, 501 Smyth Road, Ottawa, ON, Canada pbeaule@toh.on.ca.
authors.forename: P E
authors.initials: PE
authors.lastname: Beaule
keywords: DCE-MRI; Ktrans; dynamic contrast-enhanced magnetic resonance imaging; metal-on-metal total hip arthroplasty