[Evaluation of lumbar vertebral bone marrow changes with MR imaging].

Seven hundred nine magnetic resonance (MR) imaging studies of the lumbar spine were reviewed to assess the signal intensity (SI) changes in vertebral bone marrow. Marrow changes were classified into four types according to their SI changes on T 1-weighted images (T 1-WI) and T 2-WI. Type 1 changes (decreased SI on T 1-WI and increased SI on T 2-WI) were identified in 28 patients (3.9%), type 2 changes (increased SI on T 1-WI and isointense or slightly increased SI on T 2-WI) in 184 (26%), type 3 changes (decreased SI on both T 1-, T 2-WI) in 71 (10%), and type 4 changes (linearly increased SI on T 1-WI in the center of the vertebral body) in 142 (20%). Plain radiographs showed sclerotic changes in patients with type 3. In patients with type 1 or 4 changes, no focal abnormalities were observed. Histological evaluation of type 1 change revealed fibrous tissue including cartilaginous formation. Focal replacement by fatty tissue was observed in type 2 and type 4 changes. Bone sclerosis was observed in type 4 change. Type 1, type 2 and type 3 changes, which occurred commonly in the old and in the lower lumbar levels, appear to reflect a spectrum of degenerative changes of the bone marrow including both pathological and physiological ones.