Evaluating Surgical Cervical Arthrodesis With a Novel MRI Grading Score

Study Design: This was a single-institution retrospective study. Objective: Evaluate a magnetic resonance imaging (MRI)-scoring system to differentiate arthrodesis from pseudoarthrosis following anterior cervical discectomy and fusion. Summary of Background Data: Diagnostic workup following fusion surgery often includes MRI to evaluate neural structures and computed tomography (CT) and/or dynamic x-rays to evaluate instrumentation and arthrodesis. The use of MRI alone for these evaluations would protect patients from harmful CT and x-ray ionizing radiation. Methods: Neurosurgical attending evaluated CTs for arthrodesis or pseudoarthrosis. Blinded neuroradiology attending and neurosurgery senior resident evaluated independent T1 and T2 region of interest (ROI) signal intensity over instrumented disk space. Cerebral spinal fluid (CSF) at the cisterna magnum and distal adjacent uninstrumented vertebral body (VB) were also calculated. ROI_interspace/ROI_CSF and ROI_interspace/ROI_VB quotients were used to create T1- and T2-interspace interbody scores (IIS). Results: Study population (n=64 patients, 50% female) with a mean age of 51.72 years and 109 instrumented levels with 45 fused levels (41.3%) were included. T1-weighted MRI, median T1-IIS_CSF for arthrodesis was 176.20 versus 130.92 for pseudoarthrosis (P<0.0001), T1-IIS_VB for arthrodesis was 68.52 and pseudoarthrosis was 52.71 (P<0.0001). T2-weighted MRI, median T2-IIS_CSF for arthrodesis was 27.72 and 14.21 for pseudoarthrosis (P<0.0001), while T2-IIS_VB for arthrodesis was 67.90 and 41.02 for pseudoarthrosis (P<0.0001). The greatest univariable discriminative capability for arthrodesis via AUROC was T1-IIS_VB (0.7743). Conclusion: We describe a novel MRI scoring system that may help determine arthrodesis versus pseudoarthrosis following anterior cervical discectomy and fusion. Postoperative symptomatic patients may only require MRI, which would protect patients from ionizing radiation.