title: Quantifying metal-induced susceptibility artifacts of the instrumented spine at 1.5T using fast-spin echo and 3D-multispectral MRI.
abstract: To evaluate magnetic resonance imaging (MRI) artifacts near metallic spinal instrumentation using both conventional metal artifact reduction sequences (MARS) and 3D multispectral imaging sequences (3D-MSI).
  
  
  
  Both MARS and 3D-MSI images were acquired in 10 subjects with titanium spinal hardware on a 1.5T GE 450W scanner. Clinical computed tomography (CT) images were used to measure the volume of the implant using seed-based region growing. Using 30-40 landmarks, the MARS and 3D-MSI images were coregistered to the CT images. Three independent users manually segmented the artifact volume from both MR sequences. For five L-spine subjects, one user independently segmented the nerve root in both MARS and 3D-MSI images.
  
  
  
  For all 10 subjects, the measured artifact volume for the 3D-MSI images closely matched that of the CT implant volume (absolute error: 4.3 ± 2.0 cm3). The MARS artifact volume was ∼8-fold higher than that of the 3D-MSI images (30.7 ± 20.2, P = 0.002). The average nerve root volume for the MARS images was 24 ± 7.3% lower than the 3D-MSI images (P = 0.06).
  
  
  
  Compared to 3D-MSI images, the higher-resolution MARS images may help study features farther away from the implant surface. However, the MARS images retained substantial artifacts in the slice-dimension that result in a larger artifact volume. These artifacts have the potential to obscure physiologically relevant features, and can be mitigated with 3D-MSI sequences. Hence, MR study protocols may benefit with the inclusion both MARS and 3D-MSI sequences to accurately study pathology near the spine.
  
  
  
  2 J. Magn. Reson. Imaging 2017;45:51-58.
authors.affiliation: Department of Radiology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA.
authors.forename: S Sivaram
authors.initials: SS
authors.lastname: Kaushik
authors.affiliation: Department of Radiology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA.
authors.forename: Robin
authors.initials: R
authors.lastname: Karr
authors.affiliation: Department of Radiology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA.
authors.forename: Matthew
authors.initials: M
authors.lastname: Runquist
authors.affiliation: Department of Radiology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA.
authors.forename: Cathy
authors.initials: C
authors.lastname: Marszalkowski
authors.affiliation: Department of Neurosurgery, Medical College of Wisconsin, Milwaukee, Wisconsin, USA.
authors.forename: Abhishiek
authors.initials: A
authors.lastname: Sharma
authors.affiliation: Department of Radiology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA.
authors.forename: Scott D
authors.initials: SD
authors.lastname: Rand
authors.affiliation: Department of Neurosurgery, Medical College of Wisconsin, Milwaukee, Wisconsin, USA.
authors.forename: Dennis
authors.initials: D
authors.lastname: Maiman
authors.affiliation: Department of Radiology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA.
authors.forename: Kevin M
authors.initials: KM
authors.lastname: Koch
mesh_terms: D000368:Aged; D002574:Cervical Vertebrae / Q000000981:diagnostic imaging* / Q000601:surgery; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods*; D016268:Internal Fixators; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging* / Q000601:surgery; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008670:Metals; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013123:Spinal Fusion / Q000295:instrumentation*
chemical_list: D008670:Metals
keywords: 3D-MSI; MARS; MAVRIC-SL; metal artifacts; spine