Fig. 1　Imaging of lumbar foraminal stenosis. (A) The spinal nerves branch outward from the spinal canal and extend through the foramina formed between the pedicles. Lumbar foraminal stenosis is a condition in which the nerve roots are constricted inside and outside the foramen.(B) On conventional MRI this condition is diagnosed by the disappearance of the fat signal in the parasagittal image. However, the false positive rate is as high as 40%［12］. From Eguchi et al., modified with permission［17］.