Measurement of signal intensity depth profiles in rat brains with cardiac arrest using wide-field optical coherence tomography.

Three-dimensional (3D) optical coherence tomography (OCT) images of rat brain taken through the thinned skull were measured using quadrature fringe wide-field OCT (QF WF OCT) with a period of 10 min for total measurement time of 210 min stopping blood flow due to cardiac arrest, in order to investigate the potential of OCT to monitor tissue viability in brains. First, spatial resolution degradation was evaluated with QF WF OCT to demonstrate that the axial resolution was 390 microm at a thickness of 1000 microm. After cardiac arrest, the signal intensity in depth profiles increased 2.7 times compared with that before cardiac arrest. The ratio of signal intensity after euthanasia with an injection of pentobarbital sodium salt to that before sharply increased for 20 min, with stationary values of 2 to 4 overall. The trends of time variations of each position were similar. However, each stationary value depended on the 3D position.