Cervical spine: comparison of 45 degrees and 55 degrees anteroposterior oblique radiographic projections

The orientation of the intervertebral foramina (IVF) at six cervical levels on transaxial images in 65 magnetic resonance (MR) studies was determined to explain variations in size and shape evident on the 45 degrees standard radiographic oblique view. Analysis of MR imaging data showed that substantial variations in the orientation of the cervical IVFs occurred throughout the cervical spine and that a 55 degrees anteroposterior (AP) oblique view with standard radiography probably would lead to better visualization of the lower cervical IVFs. These results were confirmed with a radiographic and anatomic study of two cadaveric specimens. In a prospective clinical study of 23 patients, 45 degrees and 55 degrees AP oblique views were compared by measuring the maximal transverse diameter of all the cervical IVFs. IVF size was substantially increased on the 55 degrees AP oblique projection at all lower cervical levels. The 55 degrees AP oblique view of the cervical spine is optimal for evaluating the lower cervical foramina and can be a routine alternative to the 45 degrees oblique view in the analysis of all cervical foramina.