Quantitative in Vivo MRI Evaluation of Lumbar Facet Joints and Intervertebral Discs Using Axial T2 Mapping

Objectives: To assess the feasibility of T2 mapping of lumbar facet joints and intervertebral discs in a single imaging slab and to compare the findings with morphological grading.

Methods: Sixty lumbar spine segments from 10 low back pain patients and 5 healthy volunteers were examined by axial T2 mapping and morphological MRI at 3.0 Tesla. Regions of interest were drawn on a single slice for the facet joints and the intervertebral discs (nucleus pulposus, anterior and posterior annulus fibrosus). The Weishaupt grading was used for facet joints and the Pfirrmann score was used for morphological disc grading ("normal" vs. "abnormal" discs).

Results: The inter-rater agreement was excellent for the facet joint T2 evaluation (r = 0.85), but poor for the morphological Weishaupt grading (kappa = 0.15). The preliminary results show similar facet joint T2 values in segments with normal and abnormal Pfirrmann scores. There was no difference in mean T2 values between facet joints in different Weishaupt grading groups. Facet joint T2 values showed a weak correlation with T2 values of the posterior annulus (r = 0.32)

Conclusions: This study demonstrates the feasibility of a combined T2 mapping approach for the facet joints and intervertebral discs using a single axial slab.