Estimation of Mechanopathological Parameters Using Ultrasound Poroelastography

Abstract

Mechanical microenvironment of cancerous tumors plays an important role in the growth, metastasis and treatment of the tumors. Elevated interstitial fluid pressure (IFP) is an important component of the mechanical microenvironment of the tumor and a mechanopathological parameter of great clinical significance. Interstitial and vascular permeabilities are two other mechanopathological parameters of soft tissues that are clinically relevant and can provide useful information for cancer diagnosis and prognosis. There are a few invasive techniques that can measure IFP and the interstitial and vascular permeabilities in tissues but no non invasive imaging techniques that can assess or quantify them. In this dissertation, I propose novel, non invasive techniques based on ultrasound poroelastography, which can image these mechanopathological parameters in cancers in vivo. To achieve the goal, I developed analytical models, novel strain estimation techniques and reconstruction method for estimating the Young’s modulus and Poisson’s ratio of tumors and normal tissues. I applied my techniques on a few treated and untreated mice in a small in vivo study. The reconstructed IFP, interstitial permeability and vascular permeability were found to increase in untreated tumors with time, whereas to decrease or remain almost same in treated tumors with time. These results correlate with the results available in the literature. Based on the importance of the IFP, interstitial and vascular permeability in diagnosis, prognosis and treatment of cancers, the proposed methodology may keep important impact in quantitative cancer imaging.