This parasagittal (off the midline view from the side) T1 weighted MRI of the lumbar spine demonstrates low signal intensity in the L5 pedicle, lamina, superior and inferior articular facets which represents marrow edema. A bony defect of the L5 pars interarticularis which is called a spondylolysis. The presence of marrow edema may indicate an acute break in the bone or ongoing inflammation. Sometime a forward slip of the affected vertebrae on the one below will occur when there is spondylolysis. When this occurs it is called spondylolisthesis.