COMPUTER-ASSISTED CAROTID PLAQUE CHARACTERIZATION

Objective: To determine the relationship between plaque echogenicity a s measured by computer and the incidence of cerebral brain infarction. Patients and methods: Eighty-seven patients with 148 plaques producin g more than 50% internal carotid artery stenosis were studied. Sixty-n ine plaques were in asymptomatic patients, 35 were associated with ama urosis fugax, 19 with transient ischaemic attacks and 25 with stroke. All patients had a CT brain scan and the presence of ipsilateral cereb ral infarction was noted. Images of the plaques obtained with an ATL U ltramark-4 Duplex scanner (7.5 MHz high resolution probe) were transfe rred to a computer. Using an image analysis program a histogram for ea ch plaque was obtained with the number of pixels plotted against the g rey scale (0-225). The median of the grey scale was used as a measure of echogenicity. Results: Fifty-three (36%) of the 148 plaques were as sociated with ipsilateral CT brain infarction. Plaques with a grey sca le median more than 32 (echogenic) were associated with an incidence o f 11% (7/64) CT infarction. In contrast, plaques with grey scale media n below or equal to 32 (echolucent) were associated with 55% (46/84) i ncidence of CT infarction chi(2) = 30.35, p < 0.002, relative risk = 2 2, 95% confidence interval from 4.7 to 108). Conclusion: This study in dicates that computer analysis of carotid plaque can identify high-ris k carotid plaques. The potential of such analysis in the identificatio n of asymptomatic high-risk patients should be explored in further stu dies.