Quantitative analysis of intervertebral disc structure.

Area of Science:

• Biomedical Engineering
• Radiology
• Biophysics

Background:

• Intervertebral disc degeneration is linked to reduced signal intensity in the nucleus.
• T1 and T2 relaxation times decrease with age, indicating degeneration before clinical signs.
• Quantitative imaging can detect disc changes earlier than traditional methods.

Purpose of the Study:

• To develop and validate a robust algorithm for computing proton density, T1, and T2 values per pixel.
• To create high-resolution spatial maps of these parameters for detailed analysis of disc structure.
• To quantitatively assess in vivo changes in disc hydration and chemical environment due to aging and disease.

Main Methods:

• Developed a multiple-point algorithm to compute proton density, T1, and T2 values for each pixel.
• Utilized specially constructed coils for high-resolution imaging.
• Acquired quantitative data from volunteers, patients, and cadavers, comparing cadaveric data with cut sections.

Main Results:

• High-resolution spatial maps revealed detailed anatomical structures, including annulus laminae and hydration levels.
• In vivo analysis showed age-related changes in nucleus water content and chemical environment.
• Results correlated with known changes in glycosaminoglycan content and fixed charge density.

Conclusions:

• The developed algorithm enables in vivo measurement of disc hydration, crucial for assessing compressive load capacity.
• Quantitative spatial maps provide insights into the effects of aging and disease on disc structure.
• These methods allow for the observation of stress effects on normal intervertebral discs.