Double-lumen carotid plaque: a morbid configuration. 
During analysis of carotid plaque anatomy for a multicenter carotid imaging trial, we examined plaque specimens from 5 patients with double internal carotid artery lumina.  Four of the 5 patients had symptoms referable to the lesion.  The second lumen was noted when the plaque specimens were examined ex vivo with high-resolution (200 microm(3)) magnetic resonance imaging.  Plaque structure was correctly identified in only 1 patient preoperatively.  However, during retrospective review of the preoperative imaging studies, the second internal carotid artery lumen was identified in 3 patients.