Cross-polarization endoscopic optical coherence tomography in urology

We present results obtained using a two-channel portable device for CP OCT based on the polarization-maintaining fiber. The device is capable of acquiring OCT images of the object in direct and orthogonal polarizations simultaneously. The OCT system has an endoscopic forward-looking probe (2.7 mm in diameter). The CP OCT imaging was done in 64 postoperative specimens, for 30 patients during cystoscopy with suspicion of urothelial neoplasia, and for 11 patients with prostatectomy due to cancer. After surgery in the tissue specimen we immediately introduced surgical suture and investigated a bladder wall by CP OCT. When comparing OCT images and histology slides we can distinguish tissue layers based on position of the suture material. CP OCT images were compared with histological data. Special staining - Sirius Red for collagen types was applied. OCT -visualization of sympathetic nerve was made during open surgery. We found, that a strong signal in orthogonal polarization is produced by structures consisting of Type I collagen. We demonstrated that endoscopic benign and early malignant pathological processes that cannot be detected by standard OCT may be differentiated by CP OCT. Sympathetic nerve of neurovascular bundle gives a strong signal in both polarizations: direct and orthogonal. Based on these CP OCT features we can visualize nerve during operation (open or endoscopic surgery) and thus preserve it.