As a rule the difference in alignment between the base of the skull and the atlas is visible on plain X-ray, especially on an open mouth view of the atlas. The features are subtle, and easily mistaken for a projection error on the X-Ray.
A CT scan that covers the base of the skull and the whole of the neck will clearly show the condition. If a patient is properly positioned for a cervical spine CT scan what will be demonstrated will be the skull pointing nose up with the axis of the nose at 90 degrees to the base of the film, with the transverse axes of the vertebrae C2-C7 lying parallel to the base of the film. The atlas will be seen to be lying obliquely with the axis between the transverse processes of the atlas lying between 5-15degrees away from the transverse axes of the other cervical vertebrae. Patient positioning can be awkward in patients with marked thoracic curvature, leading to difficulty in interpreting films.
Radiological investigation also has the benefit of assessing for any condition that could be a contraindication for any physical work being done on the neck. A full list of the significant contraindications can be found at http://www.atlantotec.com.en Atlantotec is a further new technique recently developed in Switzerland, and is very similar to Atlas Profilax.