Non-­destructive estimation of blood flow velocity and elastic property through photoacoustic effect: A promising technique towards biomedical applications for brain imaging

Abstract : Technological development for quantitative measurement of flow at microscopic spatial resolution, noninvasively and nondestructively, has been an earnest demand for patho-neurological related studies of brain and is a focusing area of research. It is because of its potential applications in neurovascular coupling, the relationship between neuronal activity and hemodynamic related changes in brain, and its related studies. This talk will address design and development of microscopic imaging system (more particularly acoustic resolution photoacoustic microscopy (AR-PAM) which is based on photoacoustic effect) for estimation of blood flow velocity both direction and magnitude, simultaneously, from a set of recorded photoacoustic signals. The achievable spatial resolution is 61 μm (lateral) and 15 μm (axial), and imaging depth is 3-5 mm. Fundamentally, it is based on the quantitative measurement of Doppler frequency shift in the short laser pulse (6 ns) induced acoustic signals (known as photo-acoustic waves). The talk will extend to our study that shows the attribution of elastic property of light absorbing targets to the generation of ultrasound signals induced due to photoacoustic effect using the imaging system mentioned above. This nondestructive and noninvasive-based microscopy imaging system is a promising candidate for preclinical study and understanding of life threatening brain diseases (such as stroke, brain tumor and Alzhiemers etc.), and assessment of therapeutic treatments.