[Imaging with magnetic resonance imaging of the operated cervical spine]

The Authors report their personal experience with postoperative neuroradiologic studies in surgical patients with a herniated disk and/or degenerative cervical spondylosis. Twenty-six patients were enrolled: 16 of them underwent anterior diskectomy, 7 posterior decompressive laminectomy and 3 vertebral body removal. The patients were submitted to pre- and postoperative MRI with high field equipment (Signa 1.5 T, General Electrics), using sagittal SE T1- (TR/TE 360/15), PD and T2-weighted (TR/TE/FA 2000/40/120) sequences and T2-weighted GE axial sequences (TR/TE/FA 400/34/30). FSE sequences (TR/TE/ETL 4000/95/8) were used in 15 cases instead of the above T2-weighted SE sequences. The main postoperative MR findings were analyzed. In particular, the morphological and signal features of bone grafts, of vertebral end-plates, of the subchondral bone and of the surgical site were studied. After anterior diskectomy, the most frequent MR features were massive signal changes in the bone graft and lower vertebral plates, which were hypointense in T1 and hyperintense in T2; the adjacent subchondral bone also exhibited signal changes. Other postoperative MR findings accounted for early postoperative mobility (4 cases of persistent myelomalacia and 3 of bone graft fracture with consequent spinal instability) and late mobility (2 cases of herniated disk, 5 of spinal stenosis and one pseudomeningocele). The main limitation of MRI in postoperative cervical spine studies was the presence of ferromagnetic artifacts during SE, and even more GE, sequences; these artifacts were the main cause of misdiagnoses. In our experience, this troublesome limitation was overcome with FSE sequences but diagnostic accuracy remained poor in 4 patients. MRI, thanks to its multiparametric and multiplanar yield, is the gold standard for the examination of several early and late postoperative features and of postoperative mobility in the cervical spine. Moreover, T2-weighted FSE acquisitions are better than conventional SE to this purpose, because examination time is shorter, myelographic effect is improved and the sensitivity to ferromagnetic artifacts reduced.