The diagnostic value of MRI for lumbar disk herniation was investigated retrospectively. The midline sagittal T1-weighted images were classified into four grades according to the morphology of the intervertebral disks and the condition of the dural tube.
Grade 3 and 4 were subdivided according to the presence of the continguous epidural fat and compression of the dural tube (Takagi's classification).
MRI findings of 92 patients with lumbar disk herniatin were compared with operative findings. On the results of intraoperative findings of the 92 patients, the incidence of consistency was 91.7%. In the grade 4, showing segmentation in the posterior disk, the consistency rate was high at 100%.
In the patients with sciatica, myelography and the other images become unnecessary when the midline sagittal image demonstrates grade 3-B or 4 in the single level, and such findings were consistent with the affected side on the parasagittal or axial images.
