BACKGROUND AND OBJECTIVES: The atherosclerotic plaque in the thoracic aorta has been considered as potential source of cerebral embolization. The aim of this study was to evaluate the relation of atherosclerotic plaque burden and aortic distensibility by combined transesophageal echocardiography(TEE) and acoustic quantification(AQ) in patients with cerebral infarction without cardiac origin of emboli. METHODS: The maximal intimal-medial thickness and distensibility of descending thoracic aorta using TEE (a 7.5 MHz multiplane transducer, Hewlett Packard Sonos 2500) and AQ were prospectively measured in 36 patients(mean age ; 61+/-9 years) with cerebral infarction without cardiac origin of emboli and compared with 87 controls(mean age ; 56+/-11 years) without history of cerebral infarction. After the quality of the short-axis images of the aorta was optimized, a software of AQ was activated and gain controls were adjusted. A region of interest was mannually traced around the descending thoracic aorta and then integrated software was used to compute and instantaneously display arotic lumen area as a function of time. Maximal and minimal cross sectional area and fraction area change were calculated as an average from five consecutive heart cycle. RESULTS: There were no statistically significant differences between two groups in gender, hyperlipidemia and smoking, but hypertension and diabetes were more common in the cerebral infarction group. The atherosclerotic intimal-medial thickness above grade 3 was found in 13(36.1 %) out of 36 patients with cerebral infarction and 15(17.2%) out of 87 controls(p<0.05). Aortic areas normalized for body surface area were not statistically different between patients and normal controls, but there were significant differences for elastic indices except compliance. Patients with cerebral infarction had a lower fractional area change(5.7+/-3.2% vs. 7.8+/-4.1%, p<0.05) and higher stiffness index(12.2+/-7.7 vs. 8.0+/-5.1, p<0.05) compared with control group. There was an inverse relationship between the aortic intimal-medial thickness and the fractional area change of descending aorta(r=-0.380, p<0.01). CONCLUSION: The data suggest that the aortic distensibility noninvasively measured by TEE and AQ predicts the atherosclerotic burden. Thus the aortic distensibility may be an additive risk factor for cerebral infarction.