Oblique reformation in cervical spine computed tomography: a new look at an old friend.

STUDY

DESIGN

Cervical spine computed tomograms were evaluated for neural foraminal stenosis in both the standard axial plane and the oblique reformatted plane.

OBJECTIVE

To assess whether oblique reformation of cervical spine computed tomograms reduces interobserver variability in the evaluation of neural foraminal stenosis.

SUMMARY OF BACKGROUND DATA: Radiographic assessment of neural foraminal stenosis is subjective, may vary among observers, and can affect surgical planning.

METHODS

The cervical spine images from 19 patients with various degrees of neural foraminal stenosis were reformatted in an oblique plane perpendicular to the long axis of the right and left neural foramens. Seven independent observers graded the degree of foraminal stenosis (none, mild [1-25%], moderate [26-75%], or severe [>75%]) and their confidence level (definite, probable, possible) on both the axial images and the oblique reformations.

RESULTS

The ages of the 12 male (mean, 67.5 +/- 13.24 years) and 7 female (mean, 62.7 +/- 14.79 years) patients ranged from 39 to 83 years. Interobserver variability was assessed with chi2 analysis. Rates of agreement on degree of stenosis (chi2 = 19.94; df= 9; P< 0.02) were significantly higher for oblique reformations. Confidence ratings also were significantly higher for oblique reformations (chi2 = 18.19; df= 7; P< 0.02).

CONCLUSIONS

Oblique reformation of cervical spine images significantly reduces the degree of interobserver variability and increases observer confidence in the assessment of neural foraminal stenosis. Oblique reformations should be considered in the routine evaluation of neural foraminal stenosis.