OPTICAL IMAGING IN MEDICINE .1. EXPERIMENTAL-TECHNIQUES

The overwhelming scatter which occurs when optical radiation propagate s through tissue severely limits the ability to image internal structu re using measurements of transmitted intensity. A broad range of metho ds has been proposed during the past decade or so in order to improve imaging performance. Direct methods involve isolating an unscattered o r least-scattered component of transmitted scattered light. Indirect m ethods generally involve measuring some characteristic of the temporal distribution of transmitted light, or an equivalent in the frequency domain, and obtaining a computational solution to the inverse problem. In this paper, we review the experimental techniques which have been proposed in order to explore both direct and indirect imaging. The rel ative merits and limitations of the various experimental methods are d iscussed, and we consider the future directions and likelihood of succ ess of optical imaging in medicine.