Subventions et des contributions :

Subvention ou bourse octroyée s'appliquant à plus d'un exercice financier. (2017-2018 à 2022-2023)

BACKGROUND: Ultrasound (US) imaging is an inexpensive technique that is readily available and used extensively in human imaging and non-destructive testing, with capabilities such as real-time imaging of structure, velocity measurements of fluids using Doppler techniques, and material elasticity using a variety of approaches. Significant research is ongoing to extend the capability of US imaging to allow generation of information of other aspects of materials.

For the past 2 decades our lab has focused on exploring and developing systems used for US-guided therapy based on 3DUS (we are among the world pioneers of this technology), robotics and advanced image processing techniques such as 3D visualization, segmentation, and registration. For therapy guidance we used various techniques for thermal ablation of tissues, such as RF, microwave and lasers, with magnetic resonance imaging to map temperature of tissue. In this proposal, we propose to leverage our ongoing research and explore the capability of US imaging for 3D temperature mapping.

OBJECTIVE: Our aim is to fundamentally investigate the use of 3DUS to measure changes in temperature in materials and tissues. Specifically, over 5 years, we will pursue our aim following these objectives: (1) explore the conditions whereby 3DUS may be optimized to generate 3D temperature maps in homogenous materials as they are heated; (2) generate 3D temperature maps using 3DUS in animal tissues; (3) correlate gold standard temperature measurements and 3DUS-based temperature maps with computational models; and (4) develop methods to correct for motion of materials during 3DUS-based temperature mapping.

APPROACH: US-based temperature monitoring techniques are primarily based on two phenomena: quantification of acoustic signal shifts due to thermal expansion of the material and local changes of the speed of sound. Thus, using echo decorrelation of patches of the same location in two separate images obtained at two different temperatures, it has been shown that the decorrelation metric can be calibrated to provide information on the temperature difference. However, exploiting this approach has been hampered by motion of the material and the fact that techniques developed used 2D images, yet changes in the material due to temperature changes occurs in 3D. Thus, our research program will investigate how to leverage 3DUS imaging and motion compensation developments in our lab to be able to measure temperature changes in 3D.

NOVELTY AND EXPECTED SIGNIFICANCE: Our research program will generate new knowledge of the fundamental physics of US measurements and how 3DUS signals change with changes in temperature. We think that by combining 3DUS signal detection with motion compensation has the potential to overcome the obstacles others have faced in developing US-based thermometry and provide extended capability for US imaging in a variety of applications.