Ultrasound Diagnoses for Intraoperative Monitoring during Carotid Endarterectomy.

Carotid duplex ultrasound and transcranial Doppler (TCD) monitoring during carotid endarterectomy (CEA) is described. The safety of this procedure is crucial in determining the value of CEA. Eight CEAs have been performed at our center since the introduction of power Doppler imaging (PDI) in duplex ultrasound. PDI visualizes intravascular morphology from the integrated power of the reflected echo, mainly from red blood cells, which delineates the hypoechoic plaque. We examined the extent of stenotic lesions and plaque morphology in this series of 8 cases. PDI is useful for depicting the stenotic vessel lumen and the extent of the lesion, especially in hypoechoic atheromatous plaque, whereas conventional color Doppler flow imaging is superior for demonstrating the flow pattern in the carotid artery. Although PDI enhances surface morphology and depicts rough structures, its image quality is not adequate for delineating the ulcerative plaque surface clearly. In two cases, the distal ends of the stenotic lesion were not demonstrated due to difficulty in applying the echo probe. TCD provides hemodynamic information on the cerebral hemisphere during and after CEA, and allows prompt correction of impaired cerebral perfusion. With the aid of noninvasive monitoring using duplex scanning and TCD, CEA can be performed with real-time information on vessel shape and blood velocity, thereby reducing perioperative cerebrovascular complications.