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Part 2: Quantitative Proton T2 and Sodium Magnetic Resonance Imaging to Assess Intervertebral Disc Degeneration in a Rabbit Model

Moon, Chan Hong, PhD*; Jacobs, Lloydine, MD; Kim, Jung-Hwan, BS*; Sowa, Gwendolyn, MD, PhD†,‡; Vo, Nam, PhD; Kang, James, MD; Bae, Kyongtae Ty, MD, PhD*

doi: 10.1097/BRS.0b013e3182583447
Basic Science
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Study Design. Comparison of sodium concentration ([23Na]) and proton 2 relaxation time">T2 relaxation time between normal and degenerated discs in a rabbit model.

Objective. The purpose of this article was to evaluate quantitative [23Na] and T2 characteristics of discs associated with degenerative changes.

Summary of Background Data. Intervertebral disc degeneration is a common chronic condition that may lead to back pain, limited activity, and disability. Noninvasive imaging method to detect early intervertebral disc degeneration is vital to follow disease progression and guide clinical treatment and management.

Methods. Dual-tuned magnetic resonance imaging of rabbit discs was performed using 3T. Thirteen rabbits were included in the study; 6 control rabbits (24 normal discs) and 7 rabbits with annular puncture–induced disc degeneration (9 degenerated discs, 19 intact internal-control discs). Dual-tuned magnetic resonance imaging of discs was performed at baseline and 12-week poststab. [23Na] and T2 were measured and compared among 3 groups of discs.

Results. The mean [23Na] were 274.8 ± 40.2 mM for the normal discs, 247.2 ± 27.7 mM for the internal-control discs, and 190.6 ± 19.1 mM for the degenerated discs. The corresponding T2 for 3 groups were 97.1 ± 12.1 ms, 93.7 ± 11.9 ms, and 79.0 ± 9.1 ms, respectively. The [23Na] is highly correlated with the T2 in the degenerated discs (r = 0.90, P < 0.01). The mean percent decreases from the normal to degenerated discs were in 30.6% in [23Na] and 18.6% in T2, whereas those from the internal-control to degenerated discs were 22.9% in [23Na] and 15.6% in T2.

Conclusion. Although both [23Na] and T2 changes in discs were associated with the disc-punctured rabbits, greater change in [23Na] is observed at 12-week poststab compared with T2 change. Because T2 and [23Na] reflect different disc properties, performing both imaging under same condition will be helpful in the evaluation of disc degeneration.

We measured sodium concentration and proton T2 of the discs in an annular puncture rabbit model of intervertebral disc degeneration, using dual-tuned magnetic resonance imaging. Both T2 and sodium concentration were significantly lower in the degenerated discs than those in the normal discs. In addition, sodium concentration was more sensitive than T2 to the differences in disc status.

*Department of Radiology, University of Pittsburgh, Pittsburgh, PA

Ferguson Laboratory for Orthopaedic and Spine Research, Department of Orthopaedic Surgery, University of Pittsburgh Medical Center, Pittsburgh, PA

Department of Physical Medicine and Rehabilitation, University of Pittsburgh, Pittsburgh, PA.

Address correspondence and reprint requests to Kyongtae Ty Bae, MD, PhD, Department of Radiology, University of Pittsburgh School of Medicine, 200 Lothrop St., Pittsburgh, PA 15213; E-mail: baek@upmc.edu

Acknowledgment date: November 8, 2011. First revision date: February 20, 2012. Acceptance date: March 25, 2012.

The device(s)/drug(s) that is/are the subject of this manuscript is/are not intended for human use.

Radiological Society of North America and NIH/NCCAM grant funds were received to support this work.

One or more of the author(s) has/have received or will receive benefits for personal or professional use from a commercial party related directly or indirectly to the subject of this manuscript: e.g., honoraria, gifts, consultancies, royalties, stocks, stock options, decision-making position.

© 2012 Lippincott Williams & Wilkins, Inc.