Cervical spine (PA oblique view)
The PA oblique cervical spine projections are supplementary views to the standard AP, Odontoid and lateral c-spine series. It can be taken either as an anterior oblique or posterior oblique projection. This projection can be used to visualise the intervertebral foramina.
- patient is standing erect with either their right or left anterior side closer to the image receptor
- the thorax and cervical vertebral column at 45 degrees to the image receptor
- head in a lateral position
- posteroanterior oblique projection
- central ray has a 15 ° caudal tilt
- laterally to include the entire cervical spine and its spinous processes as well as anteriorly to include the soft tissue of the neck
- superiorly to include all of C1 and inferiorly include to at least T1 (EAM to Vertebral Prominence of C7 and/or T1)
- 18cm x 24cm
- 12.5-16 mAs
Image technical evaluation
- all of the cervical spine anatomy should be included from C1-T2
- patient’s head should be in a lateral position to prevent mandibular superimposition over the vertebral bodies of the c-spine. To ensure this ensure that the interpupillary line is perpendicular to the image receptor but also parallel to the floor
- intervertebral foramina of the side positioned closer to the image receptor should be demonstrated open 3
- make sure that any removable artefacts such as earrings, glasses or metal dentures are removed to avoid obscuring the anatomy of interest
- using a larger source to image distance will decrease magnification of the image and improves acuity 1
Correcting rotational errors
To demonstrate the intervertebral foramen of the c-spine open, it is necessary to achieve correct rotation of the vertebral column, usually at 45 degrees.
If under rotated, the foramina will be narrowed and a sternoclavicular joint would be superimposed over the vertebral column 2.
Over rotation of more than 45 degrees would cause one pedicle to be foreshortened while the other pedicle aligns to the midline of the vertebral bodies 1.
- 1. Frank E, Long B, Smith B, Merrill V. Merrill's atlas of radiographic positioning & procedures. 12th ed. Jeanne Olson;.
- 2. McQuillen-Martensen KMcQuillen-Martensen K. Radiographic image analysis workbook. 2nd ed. St. Louis, Mo.: Elsevier Saunders; 2006
- 3. Pate D. Obliques: Which Foramen Are We Looking At? [Internet]. Dynamicchiropractic.com. 2017 [cited 20 February 2017]. Available from: http://www.dynamicchiropractic.com/mpacms/dc/article.php?id=31483