Imaging the Occipital Atlanto Axial Junctions

In the case where your patient is suspected to have an Occipital-Atlanto (base of the skull - C1) or Atlanto-Axial (C1-C2) instability it may be necessary to perform and "OAA" volume study to evaluate for edema in and around the communications between the occipital bone, the atlas (C1), and the axis (C2). On MRI this is performed by utilizing a T2 weighted 3D volumetric sequence. These images show how to position the volume scan and what the volume image should look like when it is finished.

​The image at the top is a 3D reconstructed volume rendering of a CT scan of the OAA. On this image there is a red arrow pointing to a fractured dens (odontoid process) of C2. Imaging this are should be performed with very thin slices on CT. Be very careful when moving and positioning a patient suspected of an atlanto-axial subluxation or fracture. These patients should be kept as still as possible and restrained to a board to stabilize the area in order to avoid permanent damage to the spinal cord.