High-resolution spectroscopic photoacoustic tomography for noninvasive functional imaging of small-animal brains in vivo

Based on the multiwavelength laser-based photoacoustic tomography, noninvasive imaging of cerebral blood oxygenation and blood volume in small-animal brains in vivo was realized. The high sensitivity of this technique is based on the spectroscopic differences between oxy- and deoxy-hemoglobins whereas its spatial resolution is diffraction-limited by the photoacoustic signals. The point-by-point distributions of hemoglobin oxygen saturation and total concentration of hemoglobin in the cerebral cortical venous vessels, altered by systemic physiological modulations including hyperoxia and hypoxia, were visualized successfully through the intact skin and skull. This technique can potentially accelerate the progress in neuroscience and provide important new insights into cerebrovascular physiology and brain function.