Accurate ultrasound of carotid intima-media layer by pixel compounding

The intima-media thickness (IMT) of the carotid artery is an important biomarker for the clinical prognosis and diagnosis of atherosclerosis and stroke. This paper presents a new approach, pixel compounding, to enhance the resolution of the intima-media vascular layers in ultrasound B-scan images and provide increased image resolution for a more precise measurement. First, homomorphic transformation is used to estimate the lumped point spread function (PSF) of the images, then, the images are deblurred with the estimated PSF, and finally, a non-homogeneous anisotropic diffusion algorithm is used to further enhance the resolution of the image. The homogeneous part of the algorithm is used to suppress speckle while enhancing the coherent structures, specifically the edges; the non-homogeneous part (likelihood estimator) progressively adds the details from succeeding frames in the image sequence for an optimal and sub-pixel resolved image. Phantom studies have shown 300% improvement on Peak Distance Standard Deviation and nearly 100% improvement on Average Half Peak Width, indicating significant resolution enhancement.