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Reliability of Quantitative Magnetic Resonance Imaging Methods in the Assessment of Spinal Canal Stenosis and Cord Compression in Cervical Myelopathy

Karpova, Alina, MSc*; Arun, Ranganathan, DM, FRCSEd (Tr&Orth), PGDip (Orth Engin), MRCSEd*; Davis, Aileen M., PhD; Kulkarni, Abhaya V., MD, PhD, FRCSC; Mikulis, David J., MD, FRCPC§; Sooyong, Chua, MD*; Rabin, Doron, MD*; Craciunas, Sorin, MD, PhD*; Smith, Sean R., MD*; Hansen, Mitchell A., MD, PhD, FRACS*; George, Joshi, MD, EDNS, FRCSGlasg*; Fehlings, Michael G., MD, PhD, FRCSC*,†,‡

doi: 10.1097/BRS.0b013e3182672307

Study Design. Prospective, blinded reliability study of quantitative magnetic resonance imaging (MRI) measures in patients with cervical myelopathy.

Objective. To assess the intra- and interobserver reliability of commonly used quantitative MRI measures such as transverse area (TA) of spinal cord, compression ratio (CR), maximum canal compromise (MCC), and maximum spinal cord compression (MSCC).

Summary of Background Data. There is no consensus on an optimal quantitative MRI method(s) in assessing canal stenosis and cord compression.

Methods. Seven surgeons performed measurements on 17 digital MR images, on 4 separate occasions. The degree of stenosis was evaluated by measuring TA and CR on axial T2, MCC, and MSCC on midsagittal T1- and T2-weighted MRI sequences, respectively. Statistical analyses included repeated-measures analysis of variance and intraclass correlation coefficients (ICCs).

Results. The mean ± SD for intraobserver ICC was 0.88 ± 0.1 for MCC, 0.76 ± 0.08 for MSCC, 0.92 ± 0.07 for TA, and 0.82 ± 0.13 for CR. In addition, the interobserver ICC was 0.75 ± 0.04 for MCC, 0.79 ± 0.09 for MSCC, 0.80 ± 0.05 for CR, and 0.86 ± 0.03 for TA. Higher degree of canal compromise (MCC) was associated with lower modified version of Japanese Orthopaedic Association Scale score (P = 0.05). Also, a strong association was found between MSCC and lower modified version of Japanese Orthopaedic Association Scale score, greater number of steps, and longer walking time (P < 0.05).

Conclusion. All 4 measurement techniques demonstrated a good to moderately high degree of intra- and interobserver reliability. Highest reliability was noted in the assessment of T2-weighted sequences and axial MRI. Our results show that the measurements of MCC, MSCC, and CR are sufficiently reliable and correlate well with clinical severity of cervical myelopathy.

Magnetic resonance images from patients with cervical myelopathy were examined by 7 surgeons to assess the reliability of 4 quantitative magnetic resonance imaging measurements: transverse area, compression ratio, maximum spinal cord, and canal stenosis in ascertaining the severity of cervical myelopathy. All 4 parameters had high to moderate intra- and interobserver reliability.

*Division of Neurosurgery, University of Toronto, Toronto, Canada

Krembil Neuroscience Center, Toronto Western Hospital, Toronto, Canada

Gerald and Tootsie Halbert Chair, Neural Repair and Regeneration, University Health Network, Toronto Western Hospital, Toronto, Canada

§Department of Radiology, Division of Neuroradiology, University of Toronto, Toronto Western Hospital, Toronto, Canada

Division of Neurosurgery, Hospital for Sick Children, University of Toronto, Toronto, Canada; and

Health Care and Outcomes Research, Toronto Western Research Institute, University Health Network and Departments of Physical Therapy and Graduate Departments of Rehabilitation Science, Health Policy, Management and Evaluation and the Institute of Medical Science, University of Toronto, Toronto, Canada

Address correspondence and reprint requests to Michael G. Fehlings, MD, PhD, FRCSC, Krembil Chair in Neural Repair and Regeneration, The Toronto Western Hospital, University Health Network, Room 4W-449 399, Bathurst Street, Toronto, Ontario M5T 2S8, Canada; E-mail:

Acknowledgment date: September 14, 2011. First revision date: April 17, 2012. Second revision date: May 11, 2012. Acceptance date: June 26, 2012.

The manuscript submitted does not contain information about medical device(s)/drug(s).

AOSpine North America and the Ontario Neurotrauma Foundation Scholarship funds were received in support of this work.

No benefits in any form have been or will be received from a commercial party related directly or indirectly to the subject of this manuscript.

© 2013 Lippincott Williams & Wilkins, Inc.