Abstract

A novel magnetic-resonance-coupled broadband near-infrared (NIR) tomography system for small animal brain studies is described. Several features of the image formation approach are new in NIR tomography and represent major advances in the path to recovering high-resolution hemoglobin and oxygen saturation images of tissue. The NIR data were broadband and continuous wave and were used along with a second-derivative-based estimation of the path length from water absorption. The path length estimation from water was then used along with the attenuation spectrum to recover absorption and reduced scattering coefficient images at multiple wavelengths and then to recover images of total hemoglobin and oxygen saturation. Going beyond these basics of NIR tomography, software has been developed to allow inclusion of structures derived from MR imaging (MRI) for the external and internal tissue boundaries, thereby improving the accuracy and spatial resolution of the properties in each tissue type. The system has been validated in both tissue-simulating phantoms, with 10% accuracy observed, and in a rat cranium imaging experiment. The latter experiment used variation in inspired oxygen (FiO₂) to vary the observed hemoglobin and oxygen saturation images. Quantitative agreement was observed between the changes in deoxyhemoglobin values derived from NIR and the changes predicted with blood-oxygen-level-dependent (BOLD) MRI. This system represents the initial stage in what will likely be a larger role for NIR tomography, coupled to MRI, and illustrates that the technological challenges of using continuous-wave broadband data and inclusion of a priori structural information can be met with careful phantom studies.

© 2005 Optical Society of America

High-resolution near-infrared tomographic imaging simulations of the rat cranium by use of a priori magnetic resonance imaging structural information

Brian W. Pogue and Keith D. Paulsen
Opt. Lett. 23(21) 1716-1718 (1998)

Coregistration of diffuse optical spectroscopy and magnetic resonance imaging in a rat tumor model

Sean Merritt, Frederic Bevilacqua, Anthony J. Durkin, David J. Cuccia, Ryan Lanning, Bruce J. Tromberg, Gultekin Gulsen, Hon Yu, Jun Wang, and Orhan Nalcioglu
Appl. Opt. 42(16) 2951-2959 (2003)

Absorption and scattering imaging of tissue with steady-state second-differential spectral-analysis tomography

Heng Xu, Brian W. Pogue, Hamid Dehghani, Keith D. Paulsen, Roger Springett, and Jeff F. Dunn
Opt. Lett. 29(17) 2043-2045 (2004)

Simulation study of magnetic resonance imaging–guided cortically constrained diffuse optical tomography of human brain function

David A. Boas and Anders M. Dale
Appl. Opt. 44(10) 1957-1968 (2005)

Spectrally constrained chromophore and scattering near-infrared tomography provides quantitative and robust reconstruction

Subhadra Srinivasan, Brian W. Pogue, Shudong Jiang, Hamid Dehghani, and Keith D. Paulsen
Appl. Opt. 44(10) 1858-1869 (2005)