CT-Based Anatomical Evaluation of Pre-Vertebral Structures With Respect to Vertebral Body Using a Clock-Face Analogy

Area of Science:

• Spinal anatomy and surgical visualization.
• Radiological assessment of vertebral structures.

Background:

• Vascular and visceral injuries are known complications associated with pedicle screw placement.
• Accurate anatomical knowledge is crucial for preventing surgical site injuries.

Purpose of the Study:

• To define the relationship of pre-vertebral structures at each spinal level.
• To create a reference system for easier intraoperative visualization and complication avoidance.

Main Methods:

• Retrospective review of pre- and post-operative CT scans from 108 patients.
• Superimposition of a clock-face onto axial CT slices, with transverse processes (TP) at 4 and 8 o'clock.
• Analysis of 6324 CT slices to map the location of the trachea, esophagus, and aorta relative to the clock-face.

Main Results:

• The trachea's position varies from 12 to 1 o'clock between T1-T5.
• The esophagus shifts from midline (12 o'clock) at T1-T2 to 10 o'clock by T7-T9.
• The aorta's position changes from 10 o'clock at T5-T6 to 9 o'clock at T7-T8, returning to 10 o'clock from T9-T11, and appearing at 11-12 o'clock from T12-L4.

Conclusions:

• A CT-based clock-face reference system simplifies the visualization of vital pre-vertebral structures.
• This anatomical mapping aids surgeons in avoiding direct injury to these structures.
• The defined anatomical relationships are easily recalled during intraoperative procedures, enhancing surgical safety.