【报告主题】Interferometric diffusing-wave spectroscopy for blood flow monitoring of the human brain
【报告人】 周文俊 加州大学戴维斯分校
Abstract: Though cerebral blood flow (CBF) is a target parameter in neurocritical care, a non-invasive and continuous CBF monitor has remained elusive. Conventional imaging modalities such as Magnetic Resonance Imaging (MRI) and Computed Tomography (CT) are impractical for continuous monitoring, while Transcranial Doppler (TCD) Ultrasound measures velocity, not flow, and can be technically challenging. Near-infrared light technologies to measure CBF in adult humans face a unique challenge; they must sense light fluxes that are both coherent and very weak, returning from deep beneath the surface. The most successful optical CBF technology for the human brain, Diffuse Correlation Spectroscopy (DCS), uses one or more single/few mode photon counting channels, making DCS systems either expensive, or restricted in terms of speed and photon counts. Here, we reduce cost and improve performance by liberating optical CBF monitors from the expense and complexity of photon counting. The fundamental innovation is an optical “trick” known as interferometry, where the weak optical field returning from the brain is boosted by a strong reference field. This enables us to replace photon counting detectors with inexpensive pixels on a CMOS camera, in a method called interferometric Diffusing Wave Spectroscopy (iDWS). We discuss the implications of this paradigm shift for CBF monitoring and the field of diffuse optics in general.