Accessibility of the Cervicothoracic Junction Through an Anterior Approach: An MRI-based Algorithm.

STUDY DESIGN Cross-sectional observational study. OBJECTIVE To formulate a reliable method and modality for preoperative planning and to determine the effects of height, body mass index (BMI), and age on accessibility to the upper thoracic vertebrae through an anterior cervical approach. SUMMARY OF BACKGROUND DATA Various modalities have been proposed to determine the lowest spinal-level accessible through a traditional anterolateral cervical approach and the consequent need for manubriotomy. Past methods have routinely involved a variety of imaging studies such as plain radiographs and computed tomography but the reliability of these methods has not been assessed. METHODS The Magnetic Resonance Imaging (MRI) images of 180 patients classified by age and gender were evaluated and the most caudal accessible intervertebral disc space was determined from an approach angle beginning at the suprasternal notch. Plain cervical radiographs were also reviewed when available. In patients with multiple imaging studies, the reliability of the measurements was compared. Rate of accessibility was compared across different heights, BMIs, and ages. RESULTS A novel algorithm that utilized both the scout and mid-sagittal T2 MRIs was able to determine the most caudal cervicothoracic level accessible for anterior access in 93.3% of patients with a reliability of 96.8%. Conversely, plain radiograph evaluation led to low reliability (66.7%) and low agreement with MRI (60%) with an average error of one spinal level. In this patient sample, the T1 to T2 disc space was accessible in 82.7% of patients. Age and BMI were independent variables associated with accessibility (p < 0.01) while height was determined not to be significant (p = 0.09). CONCLUSION Data in this study suggest an MRI-based algorithm with a combination of scout and sagittal T2 images offers a reliable and consistent assessment of accessibility to upper thoracic levels through an anterior approach. Age and body mass index are major determinants of accessibility.