Quantative Imaging of Microbubble Ultrasound Contrast Agent with Correction of Attenuation

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The proposed research is in the general area of medical imaging. The aim is to develop novel image formation techniques for ultrasound (US) imaging using contract agents. This will improve the accuracy of US for imaging tissue containing very small blood vessels (microcirculation).In US imaging a probe, which is in contact with the patient's skin, emits an US pulse and then detects the echo signal from tissue structures within the patient. Based on these echoes images are formed. US contract agents are tiny bubbles consisting of a gas core. When injected into the vein, they allow within the blood and pass through all the blood vessels in the body. The bubbles can strongly increase the echoes and brighten up the image of tissue containing them. This enables the imaging of the microcirculation. Accurate measurement of the number of bubbles (quantification) and how this changes over time can provide useful information on tissue function . In Particular this can be invaluable in clinical investigations of patients with heartdiseases and cancer.One major cause of error in these measurements results from the decrease in loudness (attenuation) of the sound ac it travels though the tissue containing bubbles. Bubbles attenuate US in a complex way. Due to a lack of in-depth understanding of this attenuation process there is consequently no efficient way of correcting for this attenuation during image formation. This causes errors in images and consequently the estimation of the number of bubbles. The errors become even larger at deeper depth in tissue where attenuation is greater.I propose to develop novel image formation techniques with correction of attenuation, which takes into account the unique behaviour of the bubbles. Both computer simulation studies and controlled laboratory experimental measurements of the bubbles will be made to help develop and validate the proposed novel image formation techniques. Specially I propose to1) thoroughly investigate how bubbles attenuate US through computer modelling and simulation of these bubbles.2) develop a comprehensive mathematical description of the complicated process of US attenuation due to bubbles and validate it with controlled experiments.3) develop based on 1)&2) novel image formation techniques to form images of tissue containing microbubble with correction of attenuation. This results of this study is expected to make the clinical analysis of US contrast agent images more reliable.