Feature Of The Week 3/13/11: Russian Scientists Investigate Cross Polarization OCT for Early Bladder Cancer Detection
Feature Of The Week 3/13/11: This week OCT News has another exciting “Feature Of The Week” presentation of scientific results on the use of co- and cross-polarization optical coherence tomography information applied to early bladder cancer detection. The work is from the prestigious Institute of Applied and Fundamental Medicine at the Nizhny Novgorod State Medical Academy and the Institute of Applied Physics of the Russian Academy of Sciences, Nizhny Novgorod, Russia. Please note the authors have some excellent animation techniques so go slowly when viewing the slides below so the animation can complete.
Capabilities of Cross Polarization Optical Coherence Tomography (CP OCT) for early bladder cancer detection are assessed in statistical study and compared with the traditional OCT. Unlike the traditional OCT that demonstrates images only in co-polarization, CP OCT acquires images in cross-polarization and co-polarization simultaneously. 116 patients with localized flat suspicious lesions in the bladder were enrolled, 360 CP OCT images were obtained and analyzed. We used a CP OCT device with an interchangeable forward-looking endoscopic probe having outer diameter 2.7 mm described in (Gelikonov, 2006).
Benign states are generally characterized by images with high contrast between epithelium and connective tissue. Loss of contrast between layers may be caused by changes not only in the optical properties of the epithelium, but also in the submucosal layer that responds to epithelial cellular differentiation by collagen destruction and, hence, by weakening of the collagen depolarization properties. That is why assessment of biotissue depolarization properties may be useful for detecting malignization. Besides, it is well known that chronic inflammation also leads to disorganization of collagen. OCT signal in cross-polarization is formed well-organized type I collagen. This statement is based on the comparison of the intensity of a cross-polarization signal with the brightness of PSR stained collagen fiber luminescence in polarized light. The loss of collagen polarization properties due to its disorganization at neoplasia and massive inflammatory cellular infiltration significantly reduces OCT signal brightness in cross-polarization.
We compared the diagnostic capabilities of traditional OCT images (co-polarized images) and CP OCT (two images: in co- and in cross-polarization). Statistical evaluation of the diagnostic efficacy of OCT and CP OCT was also performed independently. The formulated features (Gladkova, 2010) were used for assessment of the traditional OCT images. The algorithm of making a decision of СР ОСТ images was the following. First, characteristics of the co-polarized image were analyzed. If the features were obvious, decision was taken right away. In case of doubt, final decision was taken on the basis of the cross-polarized image. Recognition of CP OCT images by the formulated features was done by 7 readers using the criteria described above. Only medical doctors familiar with CP OCT imaging and principles of interpretation of CP OCT images participated in the tests.
CP OCT has demonstrated high sensitivity 93.7% (vs. 81.2% in traditional OCT, significance level P<0.0001); specificity 84% (vs. 70.0%, P<0.001); and accuracy 85.3% (vs. 71.5%, P<0.001), which is much better than with the traditional OCT. Higher diagnostic efficacy of CP OCT in detecting early bladder cancer is associated with the ability to detect changes in epithelium and connective tissues. CP OCT can be considered an efficacious adjunct in vivo technique to assess flat suspicious lesions in the bladder initially localized by white light cystoscopy, whereas the efficacy of white light cystoscopy alone or combined with traditional OCT is much lower.
For more details see references below. Courtesy Natalia Gladkova.
N. Gladkova et. al, Cross-polarization optical coherence tomography for early bladder-cancer detection: statistical study, Journal of Biophotonics, 1-14 (2010).
V. M. Gelikonov and G. V. Gelikonov, New approach to cross-polarized optical coherence tomography based on orthogonal arbitrarily polarized modes,Laser Phys. Lett. 3, 445 (2006).
N. D. Gladkova, E. V. Zagaynova, O. S. Streltsova, et al., Advantages of cross-polarization endoscopic optical coherence tomography in diagnosis of bladder neoplasia, SPIE 7548, 754801–13 (2010).