Quantification of intervertebral disc cartilaginous endplate morphology using MRI

Introduction: The cartilaginous endplate (CEP) is a thin layer of hyaline cartilage which functions as a mechanical barrier between the nucleus pulposus and the vertebral endplate and as a gateway for nutrient transport to the intervertebral disc. To date, the geometry of the CEP has not been well defined. This study visualizes the three-dimensional morphology of the CEP and quantifies CEP thickness via a semi-automatic analysis technique. Methods: Human lumbar motion segments (n=24) were imaged using an optimized 3D FLASH sequence. MRI data were evaluated in the axial and mid-sagittal imaging planes for CEP area, circumference, anterior-posterior width, lateral width, and thickness. CEP thickness was evaluated at five anterior-posterior locations. Results: There was no significant difference in CEP circumference, area, A-P width, or lateral width with respect to superior/inferior location (p>0.7) or disc level (p>0.6) except between L1L2 and L4L5 (p<0.05) in which case L4L5 was significantly smaller in relative area. Mean CEP thickness across all disc levels and anterior-posterior locations was 0.50±0.20 mm. The CEP was found to be thinnest at the center of the disc. No correlation was found between CEP geometry and degeneration or age (p>0.5). Discussion: This study demonstrates the potential for MRI FLASH imaging coupled with automatic geometric quantification in evaluating the CEP as a potential contributor in the degenerative cascade.