  Tissue biopsy evaluation in the clinic is in need of quantitative disease
markers for diagnosis and, most importantly, prognosis. Among the new
technologies, quantitative phase imaging (QPI) has demonstrated promise for
histopathology because it reveals intrinsic tissue nanoarchitecture through the
refractive index. However, a vast majority of past QPI investigations have
relied on imaging unstained tissues, which disrupts the established specimen
processing. Here we present color spatial light interference microscopy (cSLIM)
as a new whole slide imaging modality that performs interferometric imaging
with a color detector array. As a result, cSLIM yields in a single scan both
the intrinsic tissue phase map and the standard color bright-field image,
familiar to the pathologist. Our results on 196 breast cancer patients indicate
that cSLIM can provide not only diagnostic but also prognostic information from
the alignment of collagen fibers in the tumor microenvironment. The effects of
staining on the tissue phase maps were corrected by a simple mathematical
normalization. These characteristics are likely to reduce barriers to clinical
translation for the new cSLIM technology.
