Presentation
Low back pain for months.
Patient Data
Bone marrow edema centered on the L5 pars interarticularis bilaterally without a definite complete low T1 fracture line. Minimal anterolisthesis of L5 on S1. Bilateral L5/S1 facet joint effusions with adjacent soft tissue inflammatory change.
Case Discussion
This is the acute imaging appearance of stress response in the pars interarticularis without a definitely established fracture. Whether a complete fracture has occurred can be difficult to assess on routine MRI sequences, as in this case. CT is generally helpful in this area although 3 T MRI with thin-slice T1 VIBE sequence has been shown to have comparable accuracy without the radiation dose, which is important in younger patients.