CBCT / CT Rotational Imaging
When is CBCT / CT Rotational Imaging of Cervical Spine Ordered?
CBCT / CT Rotational imaging of the cervical spine and craniocervical junction is a modality for assessment of the atlanto-axial joints (C1-C2) and is better than rotatory MRI because it has a high spatial resolution with accurate, reproducible measurements and leaves no doubt regarding the diagnosis of rotational instability.
How is CBCT / CT Rotational Imaging conducted?
It is usually obtained in the supine position (laying daown) with the head in neutral prosition, followed by maximum active lateral rotation to the left and right. This assesses the atlanto-axial joints. An increase in the rotational angle or the degree of uncovering of the atlanto-axial articular facet suggests rotational instability.
What are the disadvantages of CBCT / CT Rotational Imaging?
The disadvantages of CBCT / CT Rotational Imaging to assess atlanto-axial instability is that not all physicians agree that rotational imaging is best-practice for ruling out atlanto-axial instability due to conflicting evidence on what degree of rotation is considered abnormal; the patient’s exposure to radiation from the CT (and CBCT, although CBCT has far less radiation) and the inability to directly visualize the torn or lax ligaments.
Some CBCT machines are not capable of conducting rotational views.
Does the CBCT have less radiation than CT Scan?
Incidental and abnormal findings of the craniocervical junction were shown to have superior visualization with CBCT compared to radiography (i.e. XRays). The radiation dose to the patient for similar imaging protocols to the craniocervical junction and cervical spine was equal or less utilizing CBCT when compared to radiographs. Reference