Terahertz absorption and reflection imaging of carcinoma-affected colon tissues embedded in paraffin

•Colon adenocarcinoma detection.•Paraffin-embedded samples.•Cancer affected tissue regions, low transmittance.•High absorption coefficient and refractive index for affected tissue.•Dehydration of the tissues leads to low contrast.

In the present study, dehydrated human colon tissues embedded in paraffin were studied at THz frequency. A compact THz imaging system with high numerical aperture optics was developed for the analysis of adenocarcinoma-affected colon sections, in transmission and reflection geometry. A comprehensive analysis of the THz images revealed a contrast up to 23% between the neoplastic and control tissues. Absorption and reflection THz images demonstrated the possibility to distinguish adenocarcinoma-affected areas even without water in the tissue, as the main contrast mechanism in THz measurements has been observed to be water absorption in in vivo or freshly excised tissues. The present results corroborate with previous histologic findings in the same tissues, and confirm that the contrast prevails even in dehydrated tissues.