Depth sensitivity analysis of high-density imaging arrays for mapping brain function with diffuse optical tomography

The development of diffuse optical tomography (DOT) methods for neuroimaging of humans is challenging due to the geometry and light level constraints. A high density imaging array system has been developed and used to demonstrate the possibility of true tomographic reconstruction of cortical activity within the adult subjects which are consistent with studies using functional MRI and positron-emission tomography. This work demonstrates the benefits of using high density imaging array by investigating depth related information available from the increased number of tomographic measurements. Through the use of depth related sensitivity analysis, it is shown that the use of 4th and 5th nearest neighbor (NN) measurements, the sensitivity of the data to absorption related changes within the brain are improved dramatically, as compared to 1st, 2nd or 3rd NN measurements. Additionally, it is shown that by the use of 5th NN measurements, it is possible to recover changes at depths of up to 20 mm within the brain, which is an improvement over the use of 4th NN.