1. All of the following are measurements of occipitocervical anatomy on radiographs except:
- McRae's line
- Torg ratio
- Chamberlain's line
- Wackenheim's line
- McGregor's line
Answer: B
Discussion
The Torg ratio is a measurement of the canal height over the vertebral body diameter on the anteroposterior view. The Torg ratio is also used to assess the subaxial cervical spine for evidence of congenital stenosis; typically a ratio of 0.8 is diagnostic.
McRae's line, Chamberlain's line, Wackenheim's line, and McGregor's line aid in the evaluation of basilar invagination on conventional radiographs.
