Authors: Todd J Kowalski MD*, Kennith F Layton MD, Elie F Berbari MD, James M Steckelberg MD, Paul M Huddleston MD, John T Wald MD, Douglas R Osmon MD, MPH
Title: Follow-up Magnetic Resonance Imaging in Patients with Pyogenic Spine Infections: Correlation with Clinical Features
Addresses: Mayo Clinic, Marian Hall 5, 200 1st St. SW, Rochester, MN 55905
Purpose: Follow-up MRI examinations are increasingly used to monitor spine infection patients' response to treatment. We aim to describe follow-up MRI examination findings 4-8 weeks after diagnosis and initiation of treatment of spine infections and to compare with clinical findings
Methods: Thirty-three patients with spinal infection and available baseline and 4-8 week follow-up MRIs were included in this retrospective cohort study. Baseline and follow-up MRI were graded by two neuroradiologists blinded to clinical characteristics and outcome. Clinical findings and outcomes were independently obtained by retrospective review of the medical record.
Results: Compared with baseline MRI examinations, follow-up MRI more frequently demonstrated vertebral body compression fractures (26/33 (79%) vs 14/33 (47%); P<0.001) and less frequently demonstrated epidural enhancement (19/32 (59%) vs 29/33 (88%); P = 0.008), epidural canal abscess (3/32 (9%) vs 15/33 (45%); P = 0.001), and epidural canal compromise (10/32 (31%) vs 19/33 (58%); P = 0.008). Follow-up MRI exams demonstrated interval improvement in paraspinal inflammation (16/32 (50%)) and less epidural enhancement (21/32 (66%)). However vertebral body enhancement (24/33 (73%)), disc space enhancement (23/32 (72%)), and bone marrow edema (29/33 (88%)) more often were determined to be equivocal or worse appearing. 21 of 32 (66%) follow-up MRI exams' overall grades were considered improved, 5 (16%) equivocal and 6 (19%) worse. Follow-up MRI exams' overall grades by clinical status and clinical impact are shown in Table 1. No single MRI finding was associated with clinical status.
Discussion: Soft tissue findings, not bony findings, should be the focus of clinicians interpreting follow-up MRI results. No single MRI parameter was associated with the patients' clinical status.