Background context
Inclusion criteria consisted of patients 18 years or older, with minimal or moderate degenerative changes that underwent cervical CT for head trauma. Patients were excluded if they had pathology causing cervical central canal stenosis, previous neck surgery, or congenital spinal abnormalities. For each patient, we analyzed the diameter of the central canal using the default non-adjustable reference line on the PACS viewer. We then chose the scout angle on the midline sagittal that most bisected the endplates in a parallel fashion accounting for lordosis and kyphosis. The levels analyzed included C2 to T1 as C1-C2 does not have a disc. The two measurements were then compared directly. Statistical significance between the measurements was analyzed as well as inter-observer reliability for 3 spine surgeons who made the measurements.
Results
The average difference between the measurements of the central canal using the standard CT scout line versus the adjustable scout line ranged from -0.99 mm at the C2-C3 level and 1.85 mm at the C6-T1 level. Pearson r and ICC showed moderate to low correlation between the standard measurements and adjusted scout line measurements. Inter-observer agreement of the measurements across all levels suggested that the readers agreed on the adjustable scout line measurements more so than when using the standard CT scout line to make the measurements.
Conclusions
This study demonstrates the importance of being able to adjust the scout line in advanced cervical spine imaging in order to obtain true axial images. There are clear differences between axial slices generated with adjusted and non-adjusted scout lines particularly at disc levels that are not orthogonal to the screen edges and are common levels for cervical degenerative disc disease. Our future projects will analyze the impact of the adjustable scout line in cases with compressive pathology.
In advanced spinal imaging, an accurate assessment of central canal stenosis via axial imaging is critical. Most imaging programs, especially in regions of lordosis or kyphosis of the cervical spine, generate oblique axial images due to a fixed reference line that does not account for curves in the spine. These oblique images often misrepresent the degree of subarachnoid space between compressive structures like disc, osteophytes, ligament, or phenomenon like spondylolisthesis.
Purpose
Using PACS viewers with specialized scout line functions we will compare the cervical central canal diameter in both static and user-adjustable scout line modes.
Study Design/Setting
Retrospective image review at a Level 1 trauma center.
Patient sample
Consecutive series of 35 patients who received cervical CT.
Methods