It was recognised early in the history of optical imaging that photons which have been scattered a small number of times carry more spatial information than diffusive photons. Furthermore, if measurements could be made of minimally scattered photons, images could be reconstructed using the Radon transform as in x-ray CT, avoiding most of the difficulties associated with diffuse optical image reconstruction. Methods which can isolate minimally scattered photons from the diffusely scattered background, such as collimated detection, coherent techniques, and time-gating were reviewed in detail by Hebden et al. (1997). However, the fraction of minimally scattered photons transmitted across large (> several cm) thicknesses of tissue is immeasurably small, making this approach unsuitable for medi