title: Longitudinal assessment of hyperplasia using magnetic resonance imaging without contrast in a porcine arteriovenous graft model.
abstract: OBJECTIVE
  Chronic hemodialysis requires a vascular access that provides high blood-flow rates for the extracorporeal recirculation of blood. Synthetic arteriovenous (AV) grafts often fail because of clotting caused by underlying hyperplasia formation. The authors report the use of magnetic resonance (MR) imaging (MRI) without contrast agent to monitor tissue hyperplasia formation as well as luminal area in a porcine model of AV graft stenosis.
  
  
  METHODS
  Expanded reinforced polytetrafluoroethylene grafts were surgically placed between the common carotid artery and the external jugular vein, bilaterally, in pigs. Animals underwent MRI in a 3-T scanner at 3, 4, or 6 weeks after graft placement, followed by euthanasia and the collection of grafts and adjacent tissues for histologic analysis. Two animals underwent sequential scanning at 1, 2, 3, 5, and 7 weeks after graft placement, followed by histologic analysis.
  
  
  RESULTS
  Measurements of hyperplasia obtained from the MR images were compared with, and correlated well with, measurements obtained from the histologic cross-sections (r = 0.932, P = .02). The MR images provided a more complete view of the venous hyperplasia throughout the graft compared with histology. The MR images could be examined from multiple angles and were unaffected by histologic preparation artifacts.
  
  
  CONCLUSIONS
  Unlike histology, MRI provided longitudinal 3-dimensional views of hyperplasia within the AV grafts. This ability of MRI to more completely identify the geometry of hyperplasia and to quantify the tissue volume in vivo could provide benefits over histologic analysis in assessing the pathology of AV graft failure and the efficacy of antihyperplasia interventions.
authors.affiliation: Department of Medicine, Division of Nephrology and Hypertension, University of Utah, Salt Lake City, UT 84112, USA. christi.terry@hsc.utah.edu
authors.forename: Christi M
authors.initials: CM
authors.lastname: Terry
authors.forename: Seong-Eun
authors.initials: SE
authors.lastname: Kim
authors.forename: Li
authors.initials: L
authors.lastname: Li
authors.forename: K Craig
authors.initials: KC
authors.lastname: Goodrich
authors.forename: J Rock
authors.initials: JR
authors.lastname: Hadley
authors.forename: Donald K
authors.initials: DK
authors.lastname: Blumenthal
authors.forename: Dennis L
authors.initials: DL
authors.lastname: Parker
authors.forename: Alfred K
authors.initials: AK
authors.lastname: Cheung
mesh_terms: D000818:Animals; D001166:Arteriovenous Shunt, Surgical / Q000009:adverse effects*; D001807:Blood Vessel Prosthesis / Q000009:adverse effects*; D004195:Disease Models, Animal; D006084:Graft Rejection / Q000209:etiology* / Q000473:pathology*; D006801:Humans; D006965:Hyperplasia / Q000209:etiology / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000379:methods*; D013552:Swine