Maria Karabut

Cross-polarization optical coherence tomography for early bladder-cancer detection: statistical study.

The 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 copolarization, CP OCT acquires images in cross-polarization and copolarization simultaneously. 116 patients with localized flat suspicious lesions in the bladder were enrolled, 360 CP OCT images were obtained and analyzed. CP OCT demonstrated sensitivity 93.7% (vs. 81.2%, <0.0001), specificity 84% (vs. 70.0%, <0.001) and accuracy 85.3% (vs. 71.5%, <0.001) in detecting flat malignant bladder lesions, which is significantly 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.

Evaluation of oral mucosa collagen condition with cross-polarization optical coherence tomography

The goal of the research was analysis of the effect of collagen condition in formation of cross-polarized CP OCT images. We used of the CP OCT technique for studying collagen condition on an example of oral mucosa. Special histologic picrosirius red (PSR) staining of cheek mucosa specimens was used with subsequent assessing of the result of collagen staining in polarized light. High correlation (r = 0.692, p = 0.0001) between OCT signal standard deviation (SD) in cross-polarized images and brightness of PSR stained collagen fibers in cheek mucosa specimens was demonstrated in patients with inflammatory intestine and oral mucosa diseases. We have found that the OCT signal SD in cross-polarized images reflects two boundary conditions of collagen disorganization, namely, loss of fiber properties at active inflammation which attenuates the signal and fibrosis that occurs due to synthesis of a new remodeled collagen which amplifies the OCT signal.

Combined use of fluorescence cystoscopy and cross-polarization OCT for diagnosis of bladder cancer and correlation with immunohistochemical markers.

The combined use of fluorescence cystoscopy and cross-polarization optical coherence tomography (CP OCT) with quantitative estimation of the OCT signal was assessed in 92 bladder zones. It demonstrated the diagnostic accuracy in detecting superficial bladder cancer of 93.6%, sensitivity 96.4%, specificity 92.1%, positive predictive value 87% and negative predictive value 97.9%. Quantitative estimation of OCT signal standard deviation in cross-polarization (CP OCT SD index) makes the visual criteria of CP OCT image assessment more objective. The level of CP OCT SD index for diagnosing superficial bladder cancer, including cancer in situ, was 4.32 dB and lower. When tumor is located on a postoperative scar, CP OCT SD index may be higher than the threshold level of 4.32 dB due to strong scattering and depolarization in scar fibrous tissue. A high inverse correlation was found between CP OCT SD index and the level expressed by p63, Ki-67, p53, CD44v6 markers.

The influence on biotissue laser resection of a strongly absorbing layer at the optical fiber tip

In this paper, we consider a method of laser resection using the silica glass core from which the cladding layer has been removed as the cutting part of a laser scalpel. An absorbing layer coating the silica fiber tip markedly alters its biotissue cutting characteristics. The results of histological studies of skin after exposure to a laser scalpel with and without a strongly absorbing coating (SAC) at a wavelength of 0.97 μm show that resection using a coated scalpel is more sparing. When an uncoated scalpel was used, skin injury was more apparent in both its surface spread and the depth of structural damage, resulting in poorer tissue regeneration.

Multimodal optical coherence tomography for in vivo imaging of brain tissue structure and microvascular network at glioblastoma

In the case of infiltrative brain tumors the surgeon faces difficulties in determining their boundaries to achieve total resection. The aim of the investigation was to evaluate the performance of multimodal OCT (MM OCT) for differential diagnostics of normal brain tissue and glioma using an experimental model of glioblastoma. The spectral domain OCT device that was used for the study provides simultaneously two modes: cross-polarization and microangiographic OCT. The comparative analysis of the both OCT modalities images from tumorous and normal brain tissue areas concurrently with histologic correlation shows certain difference between when accordingly to morphological and microvascular tissue features.

Cross polarization optical coherence tomography for diagnosis of oral soft tissues

We consider the capabilities of cross-polarization OCT (CP OCT) focused on comparison of images resulting from cross-polarization and co-polarization scattering simultaneously for diagnosis of oral soft tissues. CP OCT was done for 35 patients with dental implants and 30 patients with inflammatory intestine diseases. Our study showed good diagnostic capabilities of CP OCT for detecting soft tissue pathology in the oral cavity. The cross-polarized images demonstrate the ability of tissue to depolarize. CP OCT demonstrates clinical capabilities for early diagnosis of inflammatory intestine diseases by the state of oral cavity mucosa and for early detection of gingivitis in patients above implant.

In vivo and ex vivo characterization of a novel Er fiber laser system for fractional treatment of soft oral tissues

In this work, we present the first histological in vivo and ex vivo study of effects of fractional Er fiber laser (wavelength 1550 nm, peak power 25 W) on keratinized gum and alveolar mucosa for gum regeneration. Biopsy with subsequent NBTC staining was used as primary evaluation technique. Ex vivo, porcine tissue model was used. Effects of pulse energy, beam diameter, and beam divergence were investigated in detail. It has been demonstrated that under optimal conditions columns up to 800 μm in depth could be reliably produced with 130 mJ pulses. Clinically, 2 subjects were treated and 4 punch biopsies were collected. The results were compared with ex vivo data. Both ex vivo and in vivo datasets suggest feasibility of a dental fractional system intended for gum regeneration.

Multiphoton tomography and multimodal OCT for in vivo visualization of oral malignancy in the hamster cheek pouch

The main purpose of this work is to evaluate the possibility to distinguish in vivo benign papilloma, severe dysplasia and squamous cell carcinoma by establishing quantitative image characteristics of multiphoton tomography (MPT) and multimodal optical coherence tomography images (MM OCT). Specific features of papillomatous outgrowths at different stages were revealed using 7,12-dimethylbenz[a]anthracen (DMBA)-induced hamster oral carcinoma. Analysis of MPT images included assessment of nuclear-cytoplasmic (NC) ratio, nuclear density and heterogeneity parameter F. Crosspolarization OCT images were quantified via the integral depolarization factor (IDF). Analysis of OCT microvascular maps enabled differential analysis based on the number of smallest-diameter blood vessels present in a particular pathology. Both MPT and MM OCT metrics showed some difference between benign papilloma, dysplastic papilloma, and squamous cell carcinoma tissue states. The results suggested that combined use of MPT and MM OCT have great potential for in vivo differentiation between benign and malignant papillomas.

Vessel-contrast enhancement in label-free optical coherence angiography based on phase and amplitude speckle variability

Recently proposed in vivo label-free optical coherence angiography techniques based on phase and amplitude speckle variability often require additional signal pre- and post processing operations to enhance vessel-contrast. We observe here 1) contrast enhancement by optimizing the signal normalization/weighing before processing; 2) algorithm based on Kasai estimator for phase compensation between processed A-scans to reduce masking role of motion artifacts; and 3) image projection through the imaging depth for en face plotting. We demonstrate the efficiency of proposed additional algorithms as for the microcirculation imaging of hamsters cheek in vivo as for the preliminary microcirculation imaging of patients after radiotherapy. This technical framework complete in details our recent publications on M-Mode like OCT algorithms and its implementation.

Advantages of cross-polarization endoscopic optical coherence tomography in diagnosis of bladder neoplasia

We consider the cross-polarization OCT (CP OCT) that is focused on comparison of images resulting from cross-polarization and co-polarization scattering simultaneously. This technique provides information about microstructural and biochemical alterations in depolarizing tissue components (collagen). We found that mature type I collagen gives a strong signal in orthogonal polarization. CP OCT images of benign inflammatory processes always feature signal in orthogonal polarization, with layers and borders persisting to be well defined. In the presence of precancerous alterations, signal in orthogonal polarization is available in the image but it is irregular, disappearing in some areas. A CP OCT image of bladder cancer in orthogonal polarization either shows no signal at all or a weak signal.