Compositional magnetic resonance imaging in the evaluation of the intervertebral disc: Axial vs sagittal T2 mapping

Abstract

The aim of this study was to assess T₂ values of the lumbar intervertebral discs in the axial and sagittal plane views and assess their respective interobserver reliability. The lumbar intervertebral discs of 23 symptomatic patients (11 female; 12 male; mean age, 44.1 ± 10.6; range, 24‐64 years) were examined at 3T. Region‐of‐interest (ROI) analysis was performed on axial and sagittal T₂ maps by two independent observers. ICC was assessed for every ROI. The interobserver agreement was excellent for the nucleus pulposus (NP) in the sagittal (0.951; CI95% 0.926‐0.968) and axial (0.921; CI95% 0.845‐0.955) planes. The posterior 20% region showed a higher ICC in the axial vs. the sagittal assessment (0.845; CI95 0.704‐0.911 vs. 0.819; CI95 0.744‐0.873). The same was true for the posterior 10%, with the axial region‐of‐interest showing a higher ICC (0.923; CI95 0.865‐0.953 vs. 0.628; CI95 0.495‐0.732). The intraobserver agreement was excellent for every ROI except the sagittal 10% region, which showed good performance (0.869; CI95 0.813‐0.909). The sagittal nucleus pulposus was the best‐performing region‐of‐interest with regard to intra‐ and interobserver agreement in the T₂ assessment of the lumbar intervertebral disc. However, the axial NP showed more stable agreements overall and across the value range. In addition, the annular analysis showed better inter‐ and intraobserver agreement in the axial plane view. Statement of Clinical Significance: Based on the presented analysis, we highly recommend that further studies use axial T2 mapping due to the higher intra‐ and interreader agreement.