First results of endoscopic applications of optical coherence tomography for in vivo studies of human mucosa in respiratory, gastrointestinal, urinary and genital tracts are presented. A novel endoscopic OCT (EOCT) system has been created that is based on the integration of a sampling arm of an all-optical-fiber interferometer into standard endoscopic devices using their biopsy channel to transmit low-coherence radiation to investigated tissue. We have studied mucous membranes of esophagus, larynx, stomach, urinary bladder, uterine cervix and body as typical localization for carcinomatous processes. Images of tumor tissues versus healthy tissues have been recorded and analyzed. Violations of well-defined stratified healthy mucosa structure in cancered tissue are distinctly seen by EOCT, thus making this technique promising for early diagnosis of tumors and precise guiding of excisional biopsy.

We use optical coherence tomography (OCT) to perform a comprehensive program of in vivo and in vitro structural imaging of hard and soft tissues within the oral cavity. We have imaged the different types of healthy oral mucosa as well as normal and abnormal tooth structure. OCT is able to differentiate between the various types of keratinized and non-keratinized mucosa with high resolution. OCT is also able to provide detailed structural information on clinical abnormalities (caries and non-caries lesions) in teeth and provide guidance in dental restorative procedures. Our investigations demonstrate the utility of OCT as a diagnostic imaging modality in clinical and research dentistry.

BACKGROUND/AIMS: Since the majority of skin diseases are known to be accompanied by structural alterations, research efforts are focused on the development of various novel diagnostic techniques capable of providing in vivo information on the skin structure. An essential parameter here is spatial resolution. In this paper we demonstrate the capabilities of optical coherence tomography (OCT) in detecting in vivo specific features of thin and thick skin. A particular focus is made on the identification of OCT patterns typical of certain pathological processes in skin, by performing parallel histological and tomographical studies. METHODS: To obtain images of the skin, we used a compact fiber OCT system developed at the Institute of Applied Physics of the Russian Academy of Sciences. A low coherence source (superluminescent diode) operated at a wavelength of 1280 nm; the output power was 0.5-2 mW. This power is low enough to conform to the ANSI safety standards for light exposure. The in-depth resolution limited by the spectral bandwidth (40-50 nm) of the probing light was approximately 20 &mgr;m. The lateral resolution determined by the probe light focusing ranged from 15 to 30 &mgr;m. In this series of experiments the maximum depth of imaging did not extend beyond 1.5 mm. Obtaining images of skin regions 2-6 mm long took 2-4 s. OCT capabilities for imaging normal skin of different localization and some skin diseases were studied in 12 healthy volunteers and 24 patients. RESULTS: OCT imaging of the skin can detect in vivo such general pathological reactions of the human body as active inflammation and necrosis. OCT is useful for in vivo diagnosis of some specific processes in the skin, including hyperkeratosis, parakeratosis and formation of intradermal cavities. OCT imaging is noninvasive and therefore allows frequent multifocal examination of skin without any adverse effects. OCT can perform monitoring of disease progress and recovery in the course of therapy. Morphometric studies, measurements of the depth and extension of skin pathology within the human body can be easily performed by OCT. CONCLUSIONS: OCT allows imaging of subsurface soft tissues with the spatial resolution of 15-20 &mgr;m, a resolution one order of magnitude higher than that provided by other clinically available noninvasive diagnostic techniques. An imaging depth of up to 1.5-2 mm, given by current OCT technology, is sufficient to examine the skin. Real time OCT imaging can provide information not only on the structure, but also on some specific features in the functional state, of tissues. OCT imaging is a noninvasive technique, i.e., OCT does not cause trauma and has no side effects since it utilizes radiation in the near infrared wavelength range at a power as low as 1 mW.

No abstract

The purpose of this study was to understand the capabilities and utility of optical coherence tomography (OCT) in characterizing tissue in patients with precancer and cancer of the uterine cervix and vulva. OCT is an optical technique that uses low-coherence interferometer to develop a two-dimensional image of optical scattering from internal tissue microstructure. This study was designed to develop diagnostic criteria. Women undergoing colposcopic evaluation secondary to an abnormal Papanicolaou smear or visualized grossly abnormal vulvar lesion comprised the study population. Under colposcopic visualization, the OCT device was applied to normal regions in all patients and abnormal areas when present, and images were captured. Each subject then underwent multiple directed biopsies. Images were then reviewed and compared with matched histology. A total of 50 women were recruited for the study. Of the 50 patients evaluated, 18 had cervical intraepithelial neoplasia (CIN) II,III, 14 had CIN I, 13 had metaplasia/inflammation, two had invasive squamous cell carcinoma of the cervix, and three had a diagnosis of Paget's disease of the vulva. Analysis of the OCT images showed a repetitive pattern that represented normal squamous epithelium of the cervix in 100% of the normal biopsies. Images of the 18 patients with histologically proven CIN II,III showed an unstructured homogeneous highly backscattering region with fast attenuation of the signal in 16 (89%) of the patients. OCT is a new approach for the early identification of cervix and vulvar malignancies. Using information inherent to the returning photon signals from tissue, early morphological and light-scattering changes can be detected during tumorigenesis. It has the potential to be a true optical biopsy. If diagnostically comparable to a biopsy, then clearly the ability of OCT to provide a point of service diagnosis would serve a significant advantage.