Lumbar spine: postoperative assessment with surface-coil MR imaging

Area of Science:

• Neurosurgery
• Radiology
• Spinal Imaging

Background:

• Postoperative assessment of lumbar spine surgery outcomes is crucial.
• Magnetic resonance (MR) imaging is a key tool for visualizing spinal anatomy.
• Understanding expected postoperative changes on MR imaging is essential for accurate interpretation.

Purpose of the Study:

• To evaluate the dynamic changes in lumbar spine anatomy visible on MR imaging after surgery.
• To assess the utility of MR imaging in identifying specific surgical changes and complications.
• To determine the optimal timing for MR imaging to assess postoperative lumbar spine conditions.

Main Methods:

• Prospective study of 15 patients undergoing lumbar spine surgery with pre-, immediate-, and late-postoperative MR imaging.
• Retrospective review of MR images from 62 patients with persistent low back pain after surgery.
• Analysis of epidural soft-tissue changes, mass effect, anulus disruption, and foraminal changes.

Main Results:

• Postoperative MR imaging revealed epidural soft-tissue changes and mass effect mimicking preoperative findings in many laminectomy and diskectomy patients.
• These mass effects generally improved by the late postoperative period.
• T2-weighted sagittal images effectively showed anulus disruption post-diskectomy, with resolution over time. Foraminotomy sites appeared as loss of foraminal fat signal.
• Extensive immediate postoperative changes limited MR imaging utility for symptom evaluation, except for hemorrhage detection.

Conclusions:

• Postoperative MR imaging findings in the lumbar spine evolve significantly over time.
• Early postoperative MR imaging can be challenging due to extensive soft-tissue changes.
• Late postoperative MR imaging is more reliable for assessing surgical outcomes and identifying persistent issues, with hemorrhage being an exception detectable even acutely.