Quantification of local optical properties of tissue

摘要

Optical imaging of ex vivo tissue models to study heart fibrillation is normally performed using voltage-sensitive dyes. Upon stimulation by an electrode, time-dependent fluorescence or absorption signals are recorded, often in trans-illumination geometry. In order to provide quantification of the origins of these signals inside the tissue, the locally varying optical properties of the tissue have to be known and their change due to the presence of the dyes. To provide experimental input for further modeling efforts, we have performed depth dependent measurements with a fiber optic laser source inside the tissue, recording light profiles on the tissue surface, mainly in transmission geometry. From these measurements, optical properties have been extracted and the obtained profiles have been used as input into a preliminary image reconstruction scheme, together with Monte Carlo simulations. Experiments at different locations in the same sample show the variation of optical properties. Additionally, effects from the presence of heterogeneities on the signal have been investigated.