Spine Imaging and Interventions

Multichannel CT: Evaluating the Spine in Postoperative Patients with Orthopedic Hardware

Published Online:https://doi.org/10.1148/rg.26si065512

Evaluating the spine in patients with metal orthopedic hardware is challenging. Although the effectiveness of conventional computed tomography (CT) can be limited by severe beam-hardening artifacts, the evolution of multichannel CT in recent years has made available new techniques that can help minimize these artifacts. Multichannel CT allows faster scanning times, resulting in reduced motion artifacts; thinner sections, with which it is possible to create a scanned volume of isotropic voxels with equivalent image resolution in all planes; and the generation of a higher x-ray tube current, which may result in better penetration of metal hardware and reduction of artifacts. Although 140 kVp and high milliamperage-second exposure are recommended for imaging patients with hardware, caution should always be exercised, particularly in children, young adults, and patients undergoing multiple examinations. The acquisition of multiplanar reformatted images in the axial, sagittal, coronal, and oblique planes and of three-dimensional volume-rendered images optimizes image interpretation. Wide window settings are best for reviewing images when hardware is present. The integrity of hardware is best assessed with multiplanar average intensity projection. Soft-tissue structures are best visualized by interactively varying the window width and level settings. Implementation of these techniques can yield diagnostic-quality images and aid in patient treatment.

© RSNA, 2006


  • 1 SandersWP, Truumees E. Imaging of the postoperative spine. Semin Ultrasound CT MR2004; 25: 523–535. Crossref, MedlineGoogle Scholar
  • 2 WhiteLM, Buckwalter KA. Technical considerations: CT and MR imaging in the postoperative orthopedic patient. Semin Musculoskelet Radiol2002; 6: 5–17. Crossref, MedlineGoogle Scholar
  • 3 RydbergJ, Liang Y, Teague SD. Fundamentals of multichannel CT. Semin Musculoskelet Radiol2004; 8: 137–146. Crossref, MedlineGoogle Scholar
  • 4 SainiS. Multi–detector row CT: principles and practice for abdominal applications. Radiology2004; 233: 323–327. LinkGoogle Scholar
  • 5 DalrympleNC, Prasad SR, Freckleton MW, Chintapalli KN. Introduction to the language of three-dimensional imaging with multidetector CT. RadioGraphics2005; 25: 1409–1428. LinkGoogle Scholar
  • 6 HuH. Multi-slice helical CT: scan and reconstruction. Med Phys1999; 26: 5–18. Crossref, MedlineGoogle Scholar
  • 7 RydbergJ, Liang Y, Teague SD. Fundamentals of multichannel CT. Radiol Clin North Am2003; 41: 465–474. Crossref, MedlineGoogle Scholar
  • 8 SilvermanPM, Kalender WA, Hazle JD. Common terminology for single and multislice helical CT. AJR Am J Roentgenol2001; 176: 1135–1136. Crossref, MedlineGoogle Scholar
  • 9 RobertsonDD, Weiss PJ, Fishman EK, Magid D, Walker PS. Evaluation of CT techniques for reducing artifacts in the presence of metallic orthopedic implants. J Comput Assist Tomogr1988; 12: 236–241. Crossref, MedlineGoogle Scholar
  • 10 RobertsonDD, Yuan J, Wang G, Vannier MW. Total hip prosthesis metal-artifact suppression using iterative deblurring reconstruction. J Comput Assist Tomogr1997; 21: 293–298. Crossref, MedlineGoogle Scholar
  • 11 RobertsonDD, Magid D, Poss R, Fishman EK, Brooker AF, Sledge CB. Enhanced computed tomographic techniques for the evaluation of total hip arthroplasty. J Arthroplasty1989; 4: 271–276. Crossref, MedlineGoogle Scholar
  • 12 NeymanEG, Corl FS, Fishman EK. 3D-CT evaluation of metallic implants: principles, techniques, and applications. Crit Rev Comput Tomogr2002; 43: 419–452. MedlineGoogle Scholar
  • 13 PretoriusES, Fishman EK. Volume-rendered three-dimensional spiral CT: musculoskeletal applications. RadioGraphics1999; 19: 1143–1160. LinkGoogle Scholar
  • 14 HaramatiN, Staron RB, Mazel-Sperling K, et al. CT scans through metal scanning technique versus hardware composition. Comput Med Imaging Graph1994; 18: 429–434. Crossref, MedlineGoogle Scholar
  • 15 EbraheimNA, Coombs R, Rusin JJ, Jackson WT. Reduction of postoperative CT artifacts of pelvic fractures by use of titanium implants. Orthopedics1990; 13: 1357–1358. Crossref, MedlineGoogle Scholar
  • 16 WangJC, Yu WD, Sandhu HS, Tam V, Delamarter RB. A comparison of magnetic resonance and computed tomographic image quality after the implantation of tantalum and titanium spinal instrumentation. Spine1998; 23: 1684–1688. Crossref, MedlineGoogle Scholar
  • 17 FritschEW, Heisel J, Rupp S. The failed back surgery syndrome: reasons, intraoperative findings, and long-term results—a report of 182 operative treatments. Spine1996; 21: 626–633. Crossref, MedlineGoogle Scholar
  • 18 MallJC, Kaiser JA, Heithoff KB. Postoperative spine. In: Newton TH, Potts DG, eds. Modern neuroradiology. Vol 1, Computed tomography of the spine and spinal cord. San Anselmo, Calif: Clavadel, 1983; 187–204. Google Scholar
  • 19 YooJU, Ghanayem A, Petersilge C, Lewin J. Accuracy of using computed tomography to identify pedicle screw placement in cadaveric human lumbar spine. Spine1997; 22: 2668–2671. Crossref, MedlineGoogle Scholar
  • 20 SiegelMJ, Schmidt B, Bradley D, Suess C, Hildebolt C. Radiation dose and image quality in pediatric CT: effect of technical factors and phantom size and shape. Radiology2004; 233: 515–522. LinkGoogle Scholar

Article History

Published in print: Oct 2006