ABSTRACT
In microscopy, light is minimally scattered allowing highresolution imaging but with shallow penetration depths (a few hundred micrometers). While this is suitable for imaging thin tissue sections ex vivo, it can be limiting for in vivo imaging of intact tissues. In contrast to microscopy, dižuse optical tomography (DOT) is a technique more similar to x-ray computed tomography (CT), which utilizes light to image large tissue volumes such as the breast or brain (Arridge 1999). DOT relies on a model of light scattering within the tissue to compensate for the stochastic nature of light propagation in turbid media. ™e uncertainty of the photon paths manifests as blurring and uncertainty in the reconstructed images, such that resolutions between 5 and 10 mm are typical. In between these two extremes lie a wide range of mesoscopic optical imaging techniques that aim to harness the value of optical contrast while accommodating the ežects of scattering and maximizing resolution and penetration depth. Several technologies for mesoscopic imaging have been developed in recent years. In this chapter, we examine laminar optical tomography (LOT), a mesoscopic imaging technique that measures multiply scattered light providing absorption and ¦uorescence contrast. ™e measurements collected by LOT comprise a dense tomography-like data set covering the spatial regime between that covered by microscopic and diffuse techniques. LOT was ›rst implemented in 2004 (Hillman et al. 2004) where its use was demonstrated by imaging rat cortex through a thinned skull (Hillman et al. 2007b). Since then,
several advances have been made to the technique incorporating ¦uorescence (Hillman et al. 2007a, Yuan et al. 2009a) and multispectral imaging (Burgess et al. 2008) and imaging various tissues in vivo.
