Estimation of plaque contents with multi-angle 3D compound imaging

This investigation exploits the potential of using multiple insonification angles in characterizing plaques in the carotid artery. Specifically, previous work has shown that certain plaque materials such as lipid exhibit a low degree of angle-dependence in the received echo signal while the signal varies much more with angle for fibrous tissues. An experimental multi-angle 3D pulse-echo recording system has been established with a 10 MHz focused single element transducer mounted on a high precision rotational device. The received signal was processed in order to match axial resolution size to lateral resolution size (1.4 mm@-3 dB) to obtain an omnidirectional range cell. After scanning, the plaques underwent histological analysis in order to estimate the amount of calcification, fibrous tissues, lipid, blood and thrombus. So far, 13 plaques surgically removed during carotid endarterectomy have been scanned in 3D from five different angles. Based on the angle-dependence of the signal energy for each range cell, six features could be extracted and correlated to the histological results. From the limited amount of data presented here, correlation was found between one feature and the content of fibrous tissues. The preliminary results indicate that the method has good potential for characterization of plaque.