Ultrasound characterization of arterial wall structures based on integrated backscatter profiles

Studies suggest that the composition of atherosclerotic plaque in the carotid arteries is predictive of stroke risk. The goal of this investigation has been to explore how well the true integrated backscatter (IBS) from plaque regions can be measured non-invasively using ultrasound, based on which plaque composition may be inferred. To obtain the true arterial IBS non-invasively, the scattering and aberating effect of the intervening tissue layers must be overcome. This is achieved by using the IBS from arterial blood as a reference backscatter, specifically the backscatter from a blood volume along the same scan line as and adjacent to the region of interest. The arterial blood IBS is obtained as an estimated mean of a stochastic process, after clutter removal. We have shown that the variance of the IBS estimate of the blood backscatter signal can be quantified and reduced to a tolerable level. The results are in the form of IBS profiles along the vessel. IBS profiles not normalized with the IBS of the blood-mimicking fluid have been measured for vessels phantom, with and without an intervening inhomogeneous medium; these results are contrasted with the corresponding normalized IBS profiles.