Patient with low back pain. Rule out sacroiliitis. There is a tiny focus of enhancement along the sacral margin of the right sacroiliac joint anteriorly that may represent a small degenerative cyst, but I see no frank sacroiliitis. I see no abnormal edema or enhancement of the remaining sacrum or iliac bones. There is a subcentimeter ovoid focus of abnormal signal intensity and enhancement along the left inferior articulating facet of L5 that may represent a synovial cyst arising from the facet joint, but this is equivocal and of questionable clinical significance. Low signal intensity within the pars interarticularis of L4 may represent a chronic spondylolysis, but this is equivocal as well.
No frank sacroiliitis. Questionable L4 spondylolysis and facet joint synovial cyst as above. Further evaluation with radiographs and/or lumbar spine MRI may be considered if clinically warranted.