Upright magnetic resonance imaging measurement of prevertebral soft tissue in the cervical spine of normal volunteers.

BACKGROUND CONTEXT

Anteroposterior width of prevertebral soft tissues (PVSTs) in the cervical spine has long been considered a valuable radiographic measurement for evaluation of occult cervical spine pathology. These measurements, generally obtained from lateral radiographs of the cervical spine, have been used clinically as references for the evaluation of patients with traumatic, neoplastic, or other cervical spine disorders. Magnetic resonance imaging (MRI) offers a subtle delineation of the soft-tissue structures anterior to the vertebral column, with the potential for more accurate and sensitive determination of PVST width. Upright magnetic resonance images permit comparison with and validation of previously reported upright lateral radiographic measurements of PVST width. To our knowledge, evaluation of cervical spine PVST width using upright MRI has not been previously published in the English literature.

PURPOSE

The purposes of this study were to validate lateral radiographic measurements of PVST width using upright weight-bearing MRI in healthy subjects and quantify effects of spinal level and gender.

STUDY DESIGN

Clinical study in asymptomatic volunteers.

METHODS

Eleven male and eight female volunteers consented and were enrolled in the study. All volunteers were asymptomatic and had no history of cervical spine injury or degenerative disease. Prevertebral soft-tissue width was measured at each cervical level from C2 to C7 using upright weight-bearing MRI. Statistically significant differences in PVST width based on spinal level and gender were determined using two-factor analysis of variance.

RESULTS

Width magnitudes were significantly dependent on gender (p<.0001) and spinal level (p<.0001). All C3 and C6 measurements were below the traditionally accepted values of 7 and 20 mm, respectively, that would be considered "abnormal." Prevertebral soft-tissue width was greater in men at upper and lower extents of the cervical spine. Prevertebral soft-tissue widths reported in the present study were similar in magnitude and level-by-level trends to measurements of asymptomatic volunteers obtained using lateral radiography.

CONCLUSION

The present study validated the use of lateral radiography to measure PVST width, presented level-by-level and gender-specific normative data, and provided a weighted statistical analysis of differences between normal volunteers and injured patients.