Fisher information for the design of diffuse optical brain monitoring systems

Diffuse optical tomography is a non-invasive technique for assessing tissue structure and function by detecting scattered near-infrared light. A key question is how to select source-detector configurations and measurement modalities to maximize sensitivity, particularly for brain defect (e.g., tumor, stroke, etc.) monitoring. This study proposes Fisher information as a rapid, quantitative metric to optimize source-detector placement. We compare the performance of continuous-wave and time-resolved measurements and also explore the impact of cerebrospinal fluid on system design. This method confirms some known results but also highlights some counterintuitive results, including the finding that optimal source-detector distance depends on the type of detector and its related noise statistics and that the low-scattering cerebral spinal fluid layer in the brain can enhance measurement sensitivity. This is found to depend on how exactly the data is collected and processed, with fully time-resolved data always showing a net gain. Our results provide an efficient framework for analyzing and designing diffuse optical imaging systems for non-invasive monitoring and imaging via diffuse light.