Prognostic value of 18F-FDG PET in monosegmental stenosis and myelopathy of the cervical spinal cord.

UNLABELLED MRI offers perfect visualization of spondylotic stenosis of the cervical spine, but morphologic imaging does not correlate with clinical symptoms and postoperative recovery after decompression surgery. In this prospective study, we investigated the role of (18)F-FDG PET in patients with degenerative stenosis of the cervical spinal cord in relation to postsurgical outcome. METHODS Twenty patients with monosegmental spondylotic stenosis of the middle cervical spine (C3/C4 or C4/C5) showing intramedullary hyperintensity on T2-weighted MRI and clinical symptoms of myelopathy (myelopathic patients) were investigated by (18)F-FDG PET. Maximum standardized uptake values (SUV(max)) were measured at all levels of the cervical spine (C1-C7). Decompression surgery and anterior cervical fusion were performed on all patients, and clinical status (Japanese Orthopedic Association [JOA] score) was assessed before and 6 mo after surgery. The (18)F-FDG data of 10 individuals without cervical spine pathology were used as a reference (controls). RESULTS The myelopathic patients showed a significant decrease in (18)F-FDG uptake in the area of the lower cervical cord, compared with the control group (C7 SUV(max), 1.49 ± 0.18 vs. 1.71 ± 0.27, P = 0.01). Ten myelopathic patients exhibited focally increased (18)F-FDG uptake at the level of the stenosis (SUV(max), 2.27 ± 0.41 vs. 1.75 ± 0.22, P = 0.002). The remaining 10 patients showed inconspicuous (18)F-FDG uptake at the area of the stenosis. Postoperatively, the patients with focally increased (18)F-FDG accumulation at the level of stenosis showed good clinical recovery and a significant improvement in JOA scores (13.6 ± 2.3 vs. 9.5 ± 2.5, P = 0.001), whereas no significant improvement was observed in the remaining patients (JOA score, 12.0 ± 2.4 vs. 11.6 ± 2.5, not statistically significant). Multiple regression analysis identified the presence of focally increased (18)F-FDG uptake at the level of the stenosis as an independent predictor of postoperative outcome (P = 0.002). CONCLUSION The results suggest that regional changes in (18)F-FDG uptake have prognostic significance in compression-induced cervical myelopathy that may be helpful in decisions on the timing of surgery.