Tracing the disc: The novel qualitative morphometric MRI based disc degeneration classification system

Area of Science:

• Radiology
• Orthopedics
• Medical Imaging

Background:

• Lumbar disc degeneration is a common condition.
• Existing classification systems for lumbar disc degeneration have limitations.
• Routine magnetic resonance imaging (MRI) is widely used for diagnosis.

Purpose of the Study:

• To develop a novel, easily applicable MRI-based classification system for lumbar disc degeneration.
• To compare the reliability, reproducibility, and discriminative power of the new system with the Pfirrmann classification.
• To establish a system unaffected by the limitations of existing classifications.

Main Methods:

• A new classification system grading five features (signal intensity, disc height, disc boundary regularity, nucleus-annulus separation) was developed.
• T2-weighted sagittal MRI images were acquired using specific sequences and parameters.
• Four raters classified 400 discs from 80 patients using both the Pfirrmann and the novel systems.
• Statistical analyses, including ICC and kappa values, were performed to assess reliability and correlation.

Main Results:

• The novel classification system demonstrated higher overall ICC (0.988) and kappa (0.76/0.94) values, indicating excellent intra-rater and inter-rater agreement.
• A very strong correlation (Kendall tau c = 0.872) was found between the novel and Pfirrmann classifications, supporting the validity of the new system.
• The discriminatory power of the newly added criteria was assessed through cross-tabulations.

Conclusions:

• The developed morphometric MRI-based classification system for lumbar disc degeneration is reliable and easy to use.
• This novel system offers enhanced discriminative power and may aid in generating hypotheses for treatment selection and monitoring.
• The five distinct criteria used in the new system provide new insights into the study of disc degeneration.