6th Annual Symposium
Physics of Cancer
September 7-9, 2015
|PoC - Physics of Cancer - Annual Symposium|
Biomechanics of tissue and exploring its microstructure with waves
Imaging Sciences & Biomedical Engineering Division, Kings College, London, UK
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MR-elastography (MRE) offers a unique way to non-invasively explore tissue mechanics and tissue rheology. Both provide insight into pathological processes which can be explored for characterization of tumours, staging of diffuse diseases such as liver fibrosis, but also quantification of response to therapy. MRE is based on the idea to visualize the propagation of mechanical shear waves at the cm wavelength via MRI and infer from the waves’ amplitude and phase the underlying biomechanical properties. Examples for liver fibrosis and liver/breast cancer will be given. As tissue organization is hierarchical – similar to anomalous diffusion in tissue – wave propagation in tissue also follows not a simple propagation model. This complexity - expressed in power-law dispersion behaviour - can be utilized to infer further structural information for disease characterization. However, care must be taken when trying to relate microscopic scales to macroscopic observables: the ratio between shear wavelength and obstacle size determines whether we are capable of sensing microstructure. The fractal organization of microvasculature opens another opportunity for MRE: sensing blood vessel architecture via multiple reflections of shear waves. This enables – similar to DWI – extending the resolution of MRE beyond the image resolution. Finally, the impact of local changes in blood volume/flow on apparent biomechanics will be discussed in the context of functional processes in the human brain.