MICROEMBOLI DURING CAROTID ANGIOGRAPHY - ASSOCIATION WITH STROKE RISK-FACTORS OR SUBSEQUENT MAGNETIC-RESONANCE-IMAGING CHANGES

Background and Purpose Carotid angiography is associated with a 1% ris k of major stroke. Recently, transcranial Doppler ultrasonography (TCD ) has shown cerebral microemboli during carotid angiography. To determ ine their significance, we correlated the number of microemboli during angiography with clinical characteristics, angiography findings, and preangiography and postangiography cerebral magnetic resonance imaging (MRI). Methods One middle cerebral artery was monitored with TCD in 2 4 patients during angiography for carotid territory ischemia. The numb er of microemboli was correlated with angiographic and clinical charac teristics. T2-weighted cerebral MRI was performed before and less than or equal to 48 hours after angiography, and the number of new ischemi c lesions was determined in a blinded review. Results Microemboli were seen in all patients, with an average of 51 per procedure (range, 12 to 154). The majority of microemboli had signal characteristics typica l of air. Sixteen of the 24 patients had both preangiography and posta ngiography MRI. One of 24 patients had an angiographic stroke, with a single new thalamic lesion on MRI. No other patient had a new lesion. The microembolus count correlated with the angiographic contrast volum e (P<.001) but not with any other radiological or clinical characteris tic. Conclusions This study confirmed the presence of numerous cerebra l microemboli during carotid angiography. The microembolic signal char acteristics and the correlation with contrast volume indicate that int roduced air is the cause. These microemboli are usually clinically sil ent and do not lead to new changes on cerebral MRI.