CT and duplex scanning: a comparison of imaging techniques for evaluation of the carotid tree in head and neck cancer patients.

Carotid artery disease is a common condition which, like head and neck cancer, is primarily smoking related. Internal carotid stenosis may result in cerebro-vascular complications, while severe stenosis of the external carotid can potentially compromise microvascular free tissue transfer reconstruction. We were interested to see whether any co-existing carotid artery disease could be assessed on the neck CT scan by comparing it to definitive duplex scanning in head and neck cancer patients. CT and duplex scanning of the common, internal and external carotid arteries was compared in 30 patients (180 vessels). The arterial phase of the neck CT scans were reviewed by two radiologists and all duplex scans were performed by one vascular technician to minimise inter-operator variability. The respective findings were blinded. Significant correlations were found between CT and duplex in confirming stenosis of the common and internal carotid arteries (P<0.001). There was a weak correlation between CT and duplex in the assessment of the external carotid system (P=0.02 and P=0.08), with CT under-estimating the true extent of stenosis in this vessel. The sensitivity and specificity of CT compared to duplex was 77% and 94% respectively. CT is useful not only for imaging the neck of head and neck cancer patients, but also in screening for carotid stenosis. Duplex scanning is more accurate than CT in assessing the external artery, and is useful for evaluating patients with significant stenosis of the carotid tree.