Early-stage diagnosis of cervix using PS-OCT

Screening of cervical pathology is usually performed by colposcopy or Pap-smears. However, these technologies suffer from low sensitivity since they provide information related to superficial appearances or small-sized lesion. Events occurring in sub-surface regions such as cervical intraepithelial neoplasia (CIN) are often missed when using these conventional techniques. It is clear that high-resolution tomographic techniques can help the early-stage diagnosis of cervix significantly. Optical coherence tomography (OCT) is a relatively new, non-invasive imaging technique that allows the acquisition of high-resolution tomographic images. Previous studies reported that OCT can detect the disruption of base membrane in cervix caused by cancer invasion. However, we found that sometimes the base membrane may not be visible in the OCT image even if the cervix is not in any pathological condition. It is therefore necessary to examine alternative target. It is important not only to detect cancer but to discriminate the degree of CIN (I, II, and III). These stages can be differentiated only by histological examination which can take days. It is well known that when CIN is present in cervix, the nuclear/cytoplasmic (N/C) ratio increases significantly. Since nucleus is one of the significant scattering sources, the N/C change is reflected to the OCT signals. Preliminary results with scattering phantoms show that the scattering change can be detected using polarization-sensitive OCT by estimation of OCT signal slope and depolarization with depth. In this paper, the PS-OCT system is applied to cervical tissues at various pathologic stage and the results are presented.