  Approximately 90% of cancers have their origins in epithelial tissues and
this leads to epithelial thickening, but the ultrastructural changes and
underlying architecture is less well known. Depth resolved label free
visualization of nanoscale tissue morphology is required to reveal the extent
and distribution of ultrastructural changes in underlying tissue, but is
difficult to achieve with existing imaging modalities. We developed a
nanosensitive optical coherence tomography (nsOCT) approach to provide such
imaging based on dominant axial structure with a few nanometre detection
accuracy. nsOCT maps the distribution of axial structural sizes an order of
magnitude smaller than the axial resolution of the system. We validated nsOCT
methodology by detecting synthetic axial structure via numerical simulations.
Subsequently, we validated the nsOCT technique experimentally by detecting
known structures from a commercially fabricated sample. nsOCT reveals scaling
with different depth of dominant submicron structural changes associated with
carcinoma which may inform the origins of the disease, its progression and
improve diagnosis.
