title: Adjustable shunt valve-induced magnetic resonance imaging artifact: a comparative study.
abstract: OBJECTIVE
  In this paper, the authors' goal was to compare the artifact induced by implanted (in vivo) adjustable shunt valves in spin echo, diffusion weighted (DW), and gradient echo MR imaging pulse sequences.
  
  
  METHODS
  The MR images obtained in 8 patients with proGAV and 6 patients with Strata II adjustable shunt valves were assessed for artifact areas in different planes as well as the total volume for different pulse sequences.
  
  
  RESULTS
  Artifacts induced by the Strata II valve were significantly larger than those induced by proGAV valve in spin echo MR imaging pulse sequence (29,761 vs 2450 mm(3) on T2-weighted fast spin echo, p = 0.003) and DW images (100,138 vs 38,955 mm(3), p = 0.025). Artifacts were more marked on DW MR images than on spin echo pulse sequence for both valve types.
  
  
  CONCLUSIONS
  Adjustable valve-induced artifacts can conceal brain pathology on MR images. This should influence the choice of valve implantation site and the type of valve used. The effect of artifacts on DW images should be highlighted pending the development of less MR imaging artifact-inducing adjustable shunt valves.
authors.affiliation: Victor Horsley Department of Neurosurgery, National Hospital for Neurology and Neurosurgery, Queen Square, London, United Kingdom. ahmedktoma@yahoo.com
authors.forename: Ahmed K
authors.initials: AK
authors.lastname: Toma
authors.forename: Andrew
authors.initials: A
authors.lastname: Tarnaris
authors.forename: Joan P
authors.initials: JP
authors.lastname: Grieve
authors.forename: Laurence D
authors.initials: LD
authors.lastname: Watkins
authors.forename: Neil D
authors.initials: ND
authors.lastname: Kitchen
mesh_terms: D016477:Artifacts; D001921:Brain / Q000473:pathology*; D002557:Cerebrospinal Fluid Shunts / Q000295:instrumentation*; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D004867:Equipment Design; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008838:Microcomputers; D012189:Retrospective Studies; D012984:Software; D013525:Surgical Instruments / Q000009:adverse effects*; D014025:Titanium
chemical_list: D014025:Titanium