Magnetic resonance imaging in cadaver dogs with metallic vertebral implants at 3 Tesla: evaluation of the WARP-turbo spin echo sequence.
METHODS
Laboratory investigation, ex vivo.


OBJECTIVE
Postoperative complications are common after spinal implantation procedures, and magnetic resonance imaging (MRI) would be the ideal modality to image these patients. Unfortunately, the implants cause artifacts that can render MRI nondiagnostic. The WARP-turbo spin echo (TSE) sequence has been developed to mitigate artifacts caused by metal. The objective of this investigation was to evaluate the performance of the WARP-TSE sequence in canine cadaver specimens after implantation with metallic vertebral implants.


BACKGROUND
Magnetic field strength, implant type, and MRI acquisition technique all play a role in the severity of susceptibility artifacts. The WARP-TSE sequence uses increased bandwidth, view angle tilting, and SEMAC (slice-encoding metal artifact correction) to correct for susceptibility artifact. The WARP-TSE technique has outperformed conventional techniques in patients, after total hip arthroplasty. However, published reports of its application in subjects with vertebral column implants are lacking.


METHODS
Ex vivo anterior stabilization of the atlantoaxial joint was performed on 6 adult small breed (<8 kg) cadaver dogs using stainless steel screws and polymethylmethacrylate. Axial and sagittal T2-weighted and short tau inversion recovery MRI was performed using conventional pulse sequences and WARP-TSE sequences at 3 T. Images were assessed qualitatively and quantitatively.


RESULTS
Images made with the WARP-TSE sequence had smaller susceptibility artifacts and superior spinal cord margin depiction. WARP-TSE sequences reduced the length over which susceptibility artifacts caused spinal cord margin depiction interference by 24.9% to 71.5% with scan times of approximately 12 to 16 minutes.


CONCLUSIONS
The WARP-TSE sequence is a viable option for evaluating the vertebral column after implantation with stainless steel implants.


METHODS
N/A.
*Department of Veterinary Large Animal Clinical Sciences, Texas A&M University, College Station, TX †Department of Veterinary Medicine and Surgery, University of Missouri, Columbia, MO ‡Department of Veterinary Small Animal Clinical Sciences, Texas A&M University, College Station, TX; and §Siemens Medical Solutions, Malvern, PA.
John F
JF
Griffin
Nicholas S
NS
Archambault
Joseph M
JM
Mankin
Corey R
CR
Wall
James A
JA
Thompson
Abraham
A
Padua
David
D
Purdy
Sharon C
SC
Kerwin
D000818:Animals; D016477:Artifacts; D002102:Cadaver; D004285:Dogs; D017352:Echo-Planar Imaging / Q000379:methods; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008670:Metals; D011183:Postoperative Complications / Q000175:diagnosis / Q000000981:diagnostic imaging; D019736:Prostheses and Implants; D011859:Radiography; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013131:Spine / Q000601:surgery*
D008670:Metals