SPECTROSCOPIC MARKERS OF DISC DEGENERATION

University Of California San Francisco, San Francisco CA

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Abstract

DESCRIPTION (provided by applicant): Degeneration of the intervertebral disc is a common ailment in working-age adults, affecting between 65% and 80% of the population. The intervertebral disc is thought to be a source of pain in these individuals and disc pathophysiology is well studied. The most consistent chemical change observed with degeneration is loss of proteoglycan and associated loss of water. Magnetic resonance (MR) imaging methods have been used to study disc degeneration by observing the changes in water content, relaxation and diffusion, which are an indirect by-product of alterations in biochemistry and proteoglycan content. The underlying hypothesis of this proposal is that spectroscopic markers of disc degeneration such as proteoglycan changes are detectable using high resolution Magic Angle Spinning (HRMAS) and reflect biomechanical and biochemical changes related to disc degeneration. After the milestones of this exploratory project are established it is anticipated that in vivo proton spectroscopy methods for studying these metabolites may be developed and may provide a means for in situ disc biochemical characterization and provide important, but currently unavailable information for the clinical management of low back pain. The specific goals of this project are to characterize the disc metabolites, their relative ratios and relaxation properties and to identify spectral markers for degeneration using HRMAS. The marker characteristics will be assessed as a function of Thompson Grade (degeneration) and site (annulus vs. nucleus). In addition the correlation between these markers and the biochemical composition as determined by proteoglycan and collagen assays will be established. Whole disc biomechanical properties will be characterized using three material coefficients: effective permeability of the vertebral endplate, strain dependence of the nuclear swelling pressure, and the viscoelastic behavior of the annulus fibrosus and their association with the spectral markers will be established.