Hemoglobin imaging with hybrid magnetic resonance and near-infrared diffuse tomography

This study examines the methodology of combining high-resolution information from magnetic resonance imaging into the reconstruction of near-infrared images of hemoglobin concentration and oxygen saturation. This type of hybrid imaging modality has the potential to provide noninvasive maps of hemoglobin concentration and oxygen saturation with relatively high spatial resolution with a fast time response. The study uses (i) tissue-simulating phantoms, as well as (ii) a rat cranial model, to test the method in two well-controlled situations. The phantom test demonstrates that better reconstruction accuracy can be achieved with the use of MRI-generated spatial regions in near-infrared reconstruction. The rat functional testing reveals that the technique can be applied to in vivo physiology, even in situations where the tissue is quite heterogenous. It also shows that the application of a priori structure in the finite element mesh as well as spatial constraints in the near-infrared image reconstruction, can significantly improve the quality of the resulting hemoglobin images.