Ischemia after carotid endarterectomy: comparison between transcranial Doppler sonography and diffusion-weighted MR imaging

(DWIs) are believed to correspond accurately with cerebral ischemic events. Intraoperative transcranial Doppler sonography (TCD) can reveal hemodynamic and embolic events during carotid endarterectomy (CEA). Our purpose was to determine whether the occurrence of hy-perintense signals on postoperative DWIs corresponds to intraoperative embolic or hemody-namic events. METHODS: Seventy-seven CEAs were monitored intraoperatively with TCD to record blood flow velocity changes after cross clamping to ascertain the presence of adequate collateral flow and to record microembolic signals. DWI was used to classify the hemisphere ipsilateral to the CEA by type: 0, no lesions (n 5 51); I, cortical lesions only (n 5 2); II, subcortical white matter lesions only (n 5 6); III, mixed type with cortical and subcortical lesions (n 5 11); IV, large territorial infarcts (n 5 6); and V, other types of lesions (n 5 1). RESULTS: Neither the five clinical events (one transient ischemic attack, two minor strokes, and two major strokes) nor any DWI type (I–V) showed a relationship to blood velocity de-creases after cross clamping or, in patients who were selectively shunted, to total ischemic time necessary for shunt insertion and removal. Total microembolic signal count was significantl