Apparent diffusion coefficient of intervertebral discs related to matrix composition and integrity

Area of Science:

• Biomedical Engineering
• Radiology
• Orthopedics

Background:

• Degenerative disc disease (DDD) characterization relies on invasive methods.
• A noninvasive diagnostic tool is needed to objectively assess disc matrix changes with aging and degeneration.

Purpose of the Study:

• To determine if quantitative magnetic resonance (MR) can assess intervertebral disc nutritional supply via apparent diffusion coefficients (ADCs).
• To correlate ADCs with disc matrix composition (water, glycosaminoglycan) and structural integrity.

Main Methods:

• Quantitative MR imaging was used to measure ADCs in the intervertebral disc.
• Stepwise linear regression analyses established relationships between ADCs and matrix components.
• Correlations were analyzed along different axes and between disc regions (nucleus pulposus, annulus fibrosus).

Main Results:

• Decreases in nucleus pulposus glycosaminoglycan or water content directly correlated with decreased ADCs.
• ADCs reflected changes in nucleus pulposus matrix integrity, including denatured collagen.
• Correlations were less evident in the annulus fibrosus, with only the anterior annulus fibrosus showing some reflection of matrix changes.

Conclusions:

• Apparent diffusion coefficients (ADCs) can noninvasively assess nucleus pulposus matrix composition and integrity in degenerative disc disease.
• ADCs show direction-dependent diffusion, aligning with anisotropic properties of the intervertebral disc.
• Combining ADCs with other quantitative MR parameters may provide a comprehensive, noninvasive assessment of disc health.