The invention provides a means to produce reconstructed refractive index spatial maps that reveal and allow visual separation of normal soft tissue and certain types of tumors. Detector fiber optic bundles positioned on the surface of a soft tissue organ receive and transmit scattered light data, from light in the near-infrared portion of the spectrum delivered to the surface of the organ by separate fiber optic bundles to a computer. Based on an established grid and certain assumed values, the data are analyzed by means of a complex algorithm to produce calculated refractive index values. Through iteration, the values are recalculated to minimize the difference between the observed scattering and calculated values to yield a stable map indicating spatial variation in refractive index and such variation in the form of displayed images indicates the presence of tumors in normal soft tissue.