Abstracts & Literature Review 4

Accuracy of MRI vs. CT for
Evaluating Cervical Spine Facet Arthrosis.

Ronald A. Lehman, Jr, MD, Melvin D. Helgeson, MD,* Kathryn A. Keeler, MD, Torphong
Bunmaprasert, MD, and K. Daniel Riew, MD
Spine 2008; Volume 34, Number 1, pp. 65–68.
© 2008 Lippincott Williams & Wilkins

JACO Editorial Reviewer: Timothy J. Mick, DC, DACBR
&
Michelle A. Mick (Wessely), DC, DACBR, DipMEd

Published: December, 2009
Journal of the Academy of Chiropractic Orthopedists
December 2009, Volume 6, Issue 4
Received: September 2009
Accepted: September 2009

The original article copyright belong s to the original publisher. This review is available from: http://www.dcorthoacademy.com © 2009 Mick, Wessely and the Academy of Chiropractic Orthopedists.
This is an Open Access article which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

JACO Editorial Summary

• This study was a retrospective review of cases over a 14 month period from a spine clinic that sought to determine the accuracy of MRI vs. CT in evaluating cervical spine facet joint arthrosis, a term that was not defined, but presumably synonymous with degenerative facet joint arthropathy.
• Motivation for the study included an earlier report (1) showing that facet arthropathy was a predictor of less favorable outcomes in patients who had received lumbar disc arthroplasties.
• The authors acknowledged that, although evidence exists for the lumbar spine, no similar data exists to indicate that cervical spine facet arthropathy is an important factor in the decision-making process regarding placement of an artificial disc (2,3).
• The assumption was made that significant facet arthropathy represents a contraindication to placement of cervical, artificial discs, as is the case in the lumbar spine. This presupposition should be tested, prior to a prospective study, to evaluate the importance of facet arthropathy as an exclusion criterion for cervical disc arthroplasty.
• Prior articles have examined the accuracy of various forms of diagnostic imaging in identifying and quantifying facet arthropathy in the spine, with the suggestion that CT is the most accurate method and that radiographs and MRI are less accurate, although with moderate to substantial agreement between MRI and CT or CT myelography in at least some studies. (4-7)
• It should be pointed out that, unlike some of the prior studies that involved only musculoskeletal spine radiologists in the assessment of the facet arthropathy, this retrospective study involved evaluation of imaging by both spine surgeons and radiologists. There was no specification as to sub-specialization and it is not clear as to the degree of the readers’ experience. The interpretations, at least those by the surgeons, were not made in a blinded manner, without consideration of clinical information, an obvious potential source of study bias.
• In addition to the retrospective, non-blinded nature of the study, another weakness was that CT (as opposed to surgical findings, for example) was assumed to be the “gold standard” in the diagnosis of facet arthropathy. Although the authors mentioned this, they dismissed it by indicating that, since the surgery for disc arthroplasty involved an anterior approach, it would not be feasible to assess the anatomy and histology of the facet structures, directly.
• While CT may better assess osteophytes, subchondral cysts and sclerosis, it may be inferior to MRI in identifying other findings of arthropathy, including marrow and periarticular soft tissue edema, joint effusions, and synovial cysts.
• The authors also address the potential criticism of the use of spine surgeons as well as radiologists in reviewing imaging findings, noting that the study mimicked the “normal clinical situation.” While this may be true, as mentioned earlier, this draws into question the influence of study bias and of the accuracy of the imaging interpretation when made by non-radiologists or radiologists without subspecialty training in interpretation of spine imaging.
• Finally, it is unclear as to whether or not specific parameters were established prior to the imaging interpretations, with regards to identifying and quantifying the facet arthropathy. It is possible that the reported accuracy of an examination may be influenced not only by the training and experience of the interpreter, but also by the presence or absence of a clearly agreed upon set of parameters used to establish the diagnosis of the abnormality being searched for, prior to the interpretations actually being performed. A prospective, blinded study, addressing these elements would be helpful before one could conclude, on the basis of this study, alone, that CT is essential in the evaluation of a potential candidate for cervical disc arthroplasty.

References

1. Shim CS, Lee SH, Shin HD, et al. CHARITE versus ProDisc: A comparative study of a minimum 3- year follow-up. Spine 2007;32:1012–8.
2. Anderson PA, Sasso RC, Riew KD. Update on cervical artificial disk replacement. Instr Course Lect 2007;56:237–45.
3. Acosta FL Jr, Ames CP. Cervical disc arthroplasty: general introduction. Neurosurg Clin N Am 2005;16:603–7, vi.
4. Shafaie FF, Wippold FJ II, Gado M, et al. Comparison of computed tomography myelography and magnetic resonance imaging in the evaluation of cervical spondylotic myelopathy and radiculopathy. Spine 1999;24:1781–5.
5. Butler D, Trafimow JH, Andersson GB, et al. Discs degenerate before facets. Spine 1990;15:111–3.
6. Pathria M, Sartoris DJ, Resnick D. Osteoarthritis of the facet joints: accuracy of oblique radiographic assessment. Radiology 1987;164:227–30.
7. Weishaupt D, Zanetti M, Boos N, et al. MR imaging and CT in osteoarthritis of the lumbar facet joints. Skeletal Radiol 1999;28:215–9.