C1 transverse process-hyoid bone line for preoperative evaluation of the accessible internal carotid artery on carotid endarterectomy: technical note.

BACKGROUND: The preoperative imaging diagnosis of the distal portion of the internal carotid artery (ICA) is extremely important for carotid endarterectomy (CEA). Herein the authors defined a line from the C1 transverse process to the hyoid bone (C1-H line) and evaluated whether the line can be used to predict an accessible ICA in CEA. METHODS: A cross point between the C1-H line and distal ICA was analyzed using three-dimensional computerized tomographic angiography (3D-CTA) in 20 patients. The C1-H line was compared to the line drawn from the mastoid process to the mandible (M-M line). Intraoperative exposure of the distal ICA was evaluated using both lines. Furthermore, the distance of each line from the C2 vertebra was measured to identify the distance difference of each line in relation to the cervical posture. RESULTS: A distal ICA exposed at a cross point of the C1-H line corresponded well with the intraoperative findings. The cross point between the C1-H line and distal ICA was positioned at an average of 7.0 ± 0.7 mm cranially in comparison to the M-M line. The C1-H line showed smaller distance differences at different cervical positions than the M-M line. The C1-H line moved an average of 2.8 ± 2.5 mm from a cervical neutral position to an extensional one in the perpendicular direction. CONCLUSION: The C1-H line measured by 3D-CTA is a simple and useful indicator of the distal ICA exposure in the preoperative diagnosis for CEA.