Optical Biopsy Research Articles

A 3D-printed spiral actuator for focus adjustment in circumferential scanning endomicroscopy

In this study, we showcase the design, manufacturing, and characterization of the focus adjustment actuator for use in capsule endoscopy. The actuator has a spiral flexure, carrying a lens and multiple magnets at its center to facilitate focusing through electromagnetic actuation. The interplay between the spiral flexure length and the lens size is investigated for optimal performance. An external coil is utilized to drive the lens actuator with a low power (∼5 mW) to acquire data from targets placed at multiple depths, axially spanning a range of 5 mm. The proposed actuator was intended for use in a circumferentially scanning wireless capsule endoscopy to provide high-resolution imaging at multiple depth sections throughout the gastrointestinal tract. The proposed device, targeted for confocal imaging, comprises a laser source and a light detector, the 3D-printed focus adjusting actuator to address different layers, a prism integrated micro-motor for circumferential scanning. We showcase a proof of principle data acquisition from reflective targets placed at different depths, through utilizing a scanning micromotor in conjunction with the developed focus actuator. With further development, the proposed actuator can be adapted to clinical environment to perform optical biopsies.

Utilizing deep learning for dermal matrix quality assessment on in vivo line-field confocal optical coherence tomography images.

Line-field confocal optical coherence tomography (LC-OCT) is an imaging technique providing non-invasive "optical biopsies" with an isotropic spatial resolution of ∼1 μm and deep penetration until the dermis. Analysis of obtained images is classically performed by experts, thus requiring long and fastidious training and giving operator-dependent results. In this study, the objective was to develop a new automated method to score the quality of the dermal matrix precisely, quickly, and directly from in vivo LC-OCT images. Once validated, this new automated method was applied to assess photo-aging-related changes in the quality of the dermal matrix. LC-OCT measurements were conducted on the face of 57 healthy Caucasian volunteers. The quality of the dermal matrix was scored by experts trained to evaluate the fibers' state according to four grades. In parallel, these images were used to develop the deep learning model by adapting a MobileNetv3-Small architecture. Once validated, this model was applied to the study of dermal matrix changes on a panel of 36 healthy Caucasian females, divided into three groups according to their age and photo-exposition. The deep learning model was trained and tested on a set of 15 993 images. Calculated on the test data set, the accuracy score was 0.83. As expected, when applied to different volunteer groups, the model shows greater and deeper alteration of the dermal matrix for old and photoexposed subjects. In conclusion, we have developed a new method that automatically scores the quality of the dermal matrix on in vivo LC-OCT images. This accurate model could be used for further investigations, both in the dermatological and cosmetic fields.

Confocal probe localization algorithm based on region growing and endoscope size prior

Confocal laser endomicroscopy technology can obtain cell-level images in real time and in situ, which can assist doctors in real-time intraoperative diagnosis, but its non-invasiveness makes it difficult to relocate the optical biopsy site. The confocal probe localization algorithm can automatically calculate the coordinates of the probe tip, that is, the coordinates of the optical biopsy site. In this paper, a confocal probe localization algorithm based on region growing and endoscope size prior was proposed. The algorithm detected the probe region by region growing on the probe edge image, then searched for tip points based on a given probe axis, and iteratively optimized it. Finally, based on the single-degree-of-freedom motion characteristics of the probe, the three-dimensional coordinates of the tip of the probe were calculated by using the prior information of the size of the endoscope, which solved the scale uncertainty problem of the monocular camera. The confocal probe localization algorithm was tested on the dataset collected in this paper. The results showed that our algorithm no longer relied on the color information of the probe, avoided the influence of uneven illumination on the gray value of the probe pixels, and had a more robust location accuracy and running speed. Within the length of the probe extending out of the endoscope from 0 to 5 cm, the pixel error could be as low as 11.76 pixels, and the average relative position error could be as low as 1.66 mm, which can achieve the real-time and accurate localization of the confocal probe.

Combination of Optical Biopsy with Patient Data for Improvement of Skin Tumor Identification.

In this study, patient data were combined with Raman and autofluorescence spectral parameters for more accurate identification of skin tumors. The spectral and patient data of skin tumors were classified by projection on latent structures and discriminant analysis. The importance of patient risk factors was determined using statistical improvement of ROC AUCs when spectral parameters were combined with risk factors. Gender, age and tumor localization were found significant for classification of malignant versus benign neoplasms, resulting in improvement of ROC AUCs from 0.610 to 0.818 (p < 0.05). To distinguish melanoma versus pigmented skin tumors, the same factors significantly improved ROC AUCs from 0.709 to 0.810 (p < 0.05) when analyzed together according to the spectral data, but insignificantly (p > 0.05) when analyzed individually. For classification of melanoma versus seborrheic keratosis, no statistical improvement of ROC AUC was observed when the patient data were added to the spectral data. In all three classification models, additional risk factors such as occupational hazards, family history, sun exposure, size, and personal history did not statistically improve the ROC AUCs. In summary, combined analysis of spectral and patient data can be significant for certain diagnostic tasks: patient data demonstrated the distribution of skin tumor incidence in different demographic groups, whereas tumors within each group were distinguished using the spectral differences.

Development of Advanced Imaging and Molecular Imaging for Barrett's Neoplasia.

Barrett esophagus (BE) is a precursor to a life-threatening esophageal adenocarcinoma (EAC). Surveillance endoscopy with random biopsies is recommended for early intervention against EAC, but its adherence in the clinical setting is poor. Dysplastic lesions with flat architecture and patchy distribution in BE are hardly detected by high-resolution endoscopy, and the surveillance protocol entails issues of time and labor and suboptimal interobserver agreement for diagnosing dysplasia. Therefore, the development of advanced imaging technologies is necessary for Barrett’s surveillance. Recently, non-endoscopic or endoscopic technologies, such as cytosponge, endocytoscopy, confocal laser endomicroscopy, autofluorescence imaging, and optical coherence tomography/volumetric laser endomicroscopy, were developed, but most of them are not clinically available due to the limited view field, expense of the equipment, and significant time for the learning curve. Another strategy is focused on the development of molecular biomarkers, which are also not ready to use. However, a combination of advanced imaging techniques together with specific biomarkers is expected to identify morphological abnormalities and biological disorders at an early stage in the surveillance. Here, we review recent developments in advanced imaging and molecular imaging for Barrett’s neoplasia. Further developments in multiple biomarker panels specific for Barrett’s HGD/EAC include wide-field imaging systems for targeting ‘red flags’, a high-resolution imaging system for optical biopsy, and a computer-aided diagnosis system with artificial intelligence, all of which enable a real-time and accurate diagnosis of dysplastic BE in Barrett’s surveillance and provide information for precision medicine.

Our Initial Experience in Optical Coherence Tomography in Peripheral Vasculature

Background: Optical coherence tomography (OCT) has been a cornerstone for intracoronary interventions for substantial years. The extrapolation of the benefits of this cutting-edge technology to the peripheral vasculature is still in its nascent stage. This pictorial essay was an endeavor to exhibit the role of OCT as a tool for visualization of peripheral vasculature. Aim: To ascertain adjunctive use of intravascular imaging through OCT of in vivo peripheral human arterial vasculature and to distinguish between lipid-rich, fibrous, and calcified atherosclerotic plaques and other lesions of peripheral vasculature. Subjects and Methods: OCT imaging was performed with commercially available OCT system which is a short mono-rail design with a fiberoptic imaging core integrated into a catheter. The optic imaging core rotates at a rate of 100–180 revolutions/s. OCT pull backs were performed in an automated fashion with simultaneous flushing of iso-osmolar contrast (Visipaque) and normal saline. The visualization of different lesions of peripheral human vasculature through the eye of OCT is presented here as a pictorial essay. Results: OCT has an evolving potential as a tool for monitoring, lesion characterization, assessment of retrogression, progression, and disease stabilization in peripheral vasculature. The technique provides optimal high-resolution lesion characterization akin to an optical biopsy. Conclusions: OCT as a tool for in vivo analysis of human peripheral vasculature provides superlative results. Larger studies will be required to validate a protocol for optimal usage in the peripheral human arteries.

Tri-mode optical biopsy probe with fluorescence endomicroscopy, Raman spectroscopy, and time-resolved fluorescence spectroscopy.

We present an endoscopic probe that combines three distinct optical fibre technologies including: A high-resolution imaging fibre for optical endomicroscopy, a multimode fibre for time-resolved fluorescence spectroscopy, and a hollow-core fibre with multimode signal collection cores for Raman spectroscopy. The three fibers are all enclosed within a 1.2 mm diameter clinical grade catheter with a 1.4 mm end cap. To demonstrate the probe's flexibility we provide data acquired with it in loops of radii down to 2 cm. We then use the probe in an anatomically accurate model of adult human airways, showing that it can be navigated to any part of the distal lung using a commercial bronchoscope. Finally, we present data acquired from fresh ex vivo human lung tissue. Our experiments show that this minimally invasive probe can deliver real-time optical biopsies from within the distal lung - simultaneously acquiring co-located high-resolution endomicroscopy and biochemical spectra.

Superficial bladder cancer diagnosis — the deliberate choice between fluorescent diagnosis and optical biopsy

Bladder carcinoma in situ (CIS) is a potentially invasive tumor whose early detection is a key step to ensuring the preservation of the bladder, reducing mortality, and improving the quality of patients’ life. The early diagnosis of bladder cancer requires a sensitive technique that can detect the lesion to determine its stage and grade. ALA induced-PpIX makes it possible to detect tumors with 90% sensitivity. ALA hexyl ester (hALA) increases the sensitivity to 95%. Macroscopic techniques require a histological biopsy to define the tumor invasiveness. Imaging with Fibered Optic Confocal Fluorescence Microscopy allows the optical sectioning of examined tissues providing images with subcellular resolution after labeling with adequate fluorescent dye chosen based on the sensitivity of the used device. Available fluorescent agents are compatible with used devices; however, their toxicity and mutagenesis studies are unsatisfactory. During imaging, an optical fiber is introduced into the bladder via the urethra and placed in contact with the bladder wall. The distinction between the different types of epithelial cells is based on the cell size, morphology, and signal intensity. Although not fully adopted for clinical application, the FOCM represents a real asset that reduces invasiveness and complements the fluorescence-based endoscopy.

Automatic optical biopsy for colorectal cancer using hyperspectral imaging and artificial neural networks.

Intraoperative identification of cancerous tissue is fundamental during oncological surgical or endoscopic procedures. This relies on visual assessment supported by histopathological evaluation, implying a longer operative time. Hyperspectral imaging (HSI), a contrast-free and contactless imaging technology, provides spatially resolved spectroscopic analysis, with the potential to differentiate tissue at a cellular level. However, HSI produces "big data", which is impossible to directly interpret by clinicians. We hypothesize that advanced machine learning algorithms (convolutional neural networks-CNNs) can accurately detect colorectal cancer in HSI data. In 34 patients undergoing colorectal resections for cancer, immediately after extraction, the specimen was opened, the tumor-bearing section was exposed and imaged using HSI. Cancer and normal mucosa were categorized from histopathology. A state-of-the-art CNN was developed to automatically detect regions of colorectal cancer in a hyperspectral image. Accuracy was validated with three levels of cross-validation (twofold, fivefold, and 15-fold). 32 patients had colorectal adenocarcinomas confirmed by histopathology (9 left, 11 right, 4 transverse colon, and 9 rectum). 6 patients had a local initial stage (T1-2) and 26 had a local advanced stage (T3-4). The cancer detection performance of the CNN using 15-fold cross-validation showed high sensitivity and specificity (87% and 90%, respectively) and a ROC-AUC score of 0.95 (considered outstanding). In the T1-2 group, the sensitivity and specificity were 89% and 90%, respectively, and in the T3-4 group, the sensitivity and specificity were 81% and 93%, respectively. Automatic colorectal cancer detection on fresh specimens using HSI, using a properly trained CNN is feasible and accurate, even with small datasets, regardless of the local tumor extension. In the near future, this approach may become a useful intraoperative tool during oncological endoscopic and surgical procedures, and may result in precise and non-destructive optical biopsies to support objective and consistent tumor-free resection margins.

Characterization of ex vivo and in vivo intraoperative neurosurgical confocal laser endomicroscopy imaging.

BackgroundThe new US Food and Drug Administration-cleared fluorescein sodium (FNa)-based confocal laser endomicroscopy (CLE) imaging system allows for intraoperative on-the-fly cellular level imaging. Two feasibility studies have been completed with intraoperative use of this CLE system in ex vivo and in vivo modalities. This study quantitatively compares the image quality and diagnostic performance of ex vivo and in vivo CLE imaging.MethodsImages acquired from two prospective CLE clinical studies, one ex vivo and one in vivo, were analyzed quantitatively. Two image quality parameters – brightness and contrast – were measured using Fiji software and compared between ex vivo and in vivo images for imaging timing from FNa dose and in glioma, meningioma, and intracranial metastatic tumor cases. The diagnostic performance of the two studies was compared.ResultsOverall, the in vivo images have higher brightness and contrast than the ex vivo images (p < 0.001). A weak negative correlation exists between image quality and timing of imaging after FNa dose for the ex vivo images, but not the in vivo images. In vivo images have higher image quality than ex vivo images (p < 0.001) in glioma, meningioma, and intracranial metastatic tumor cases. In vivo imaging yielded higher sensitivity and negative predictive value than ex vivo imaging.ConclusionsIn our setting, in vivo CLE optical biopsy outperforms ex vivo CLE by producing higher quality images and less image deterioration, leading to better diagnostic performance. These results support the in vivo modality as the modality of choice for intraoperative CLE imaging.

OPTICAL BIOPSY AND ARTIFICIAL INTELLIGENCE AS A DIAGNOSTIC TOOL OF SMOKERS: A PILOT STUDY

<h3>Objectives</h3> Compare saliva between smoking and nonsmoking patients by Fourier transform infrared (FT-IR) spectroscopy as an optical biopsy technique and associate with data processing methods based on artificial intelligence. It will be possible to investigate biochemical changes at the molecular level and in the future use it for early diagnosis of oral cancer. <h3>Study Design</h3> This study was approved by the research ethics committee and was conducted using FT-IR spectroscopy coupled with and attenuated total reflection accessory. Volunteers were divided into 3 groups; however, only 10 patients were analyzed as a pilot study. In the control group, saliva of volunteers who had never tried tobacco (5 samples) was collected. The smoking group consisted of patients over 40 years old who smoke more than one pack of cigarettes a day (1 sample). The sporadic smoking group included patients who smoke sporadically (4 samples). <h3>Results</h3> In all groups, the structural components DNA, RNA, lipids, proteins, and amide were assessed. The spectra showed different intensities in the respective structural components mentioned above, so that subtle differences could prove that the saliva of smoking patients exhibits differences from saliva of nonsmoking patients. <h3>Conclusions</h3> Optical biopsy and artificial intelligence could be used in the medical field.

Deep learning-enabled soft tissue tumor localization using spatially offset Raman spectral analysis: in-silico investigations

Raman spectroscopy and its derivatives have gained wide acceptance among optical biopsy tools for tissue discrimination. However, the identification and localization of subsurface soft tissue tumors are still challenging. Several designs for the Raman probe have been proposed to this effect, among which spatially offset Raman spectroscopy (SORS) could offer a potential solution. This paper attempts to demonstrate the simultaneous identification of subsurface adenoma depth and thickness using Convolutional Neural Networks applied on Monte Carlo simulated SORS signals. The application of transfer learning model resulted in a better root mean square error (RMSE) of 4.40% for depth prediction as compared to the 7%–25% RMSE demonstrated by previous reports. Simultaneous thickness prediction is demonstrated for the first time with 8.42% RMSE.

In vivo visualisation of tattoo particles using multiphoton tomography and fluorescence lifetime imaging.

With increased popularity of decorative tattoos, awareness of tattoo-based dermatological complications has been raised. Health issues include a broad spectrum dominated by allergies and infections. To examine the etiopathology and prognose the outcome of an appropriate therapy, a non-invasive intravital diagnostic approach is indicated. The present pilot study introduces multiphoton tomography equipped with fluorescence lifetime imaging as a diagnostic technique to examine the morphological and metabolic status of tattooed human skin at patient's bedside. The distributing course of tattoo particles can be visualised over time. By providing optical biopsies, inflammation-based alterations in freshly tattooed skin and tattoo complications can be analysed. The study concludes that multiphoton tomography combined with fluorescence lifetime imaging is a suitable technique for in vivo visualisation of tattoo pigments as well as for the assessment of quantitative and qualitative skin changes after injection of tattoo ink into human skin.

Multi-focus image fusion with enhancement filtering for robust vascular quantification using photoacoustic microscopy.

Accurate identification and quantification of microvascular patterns are important for clinical diagnosis and therapeutic monitoring using optical-resolution photoacoustic microscopy (OR-PAM). Due to its limited depth of field, conventional OR-PAM may not fully reveal microvascular patterns with enough details in depth range, which affects the segmentation and quantification. Here, we propose a robust vascular quantification approach via combining multi-focus image fusion with enhancement filtering (MIFEF). The multi-focus image fusion is constructed based on multi-scale gradients and image matting to improve image fusion quality by considerably achieving accurate focus measurement for initial segmentation as well as decision map refinement. The enhancement filtering identifies the vessels and handles noise without deforming microvasculature. The performance of the MIFEF were evaluated employing a leaf phantom, mouse livers and brains. The proposed method for OR-PAM can significantly facilitate the clinical provision of optical biopsy of vascular-related diseases.

Multimodal system for optical biopsy of melanoma with integrated ultrasound, optical coherence tomography and Raman spectroscopy.

We introduce a new single-head multimodal optical system that integrates optical coherence tomography (OCT), 18 MHz ultrasound (US) tomography and Raman spectroscopy (RS), allowing for fast (<2 min) and noninvasive skin cancer diagnostics and lesion depth measurement. The OCT can deliver structural and depth information of smaller skin lesions (<1 mm), while the US allows to measure the penetration depth of thicker lesions (≥4 mm), and the RS analyzes the chemical composition from a small chosen spot (≤300 μm) that can be used to distinguish between benign and malignant melanoma. The RS and OCT utilize the same scanning and optical setup, allowing for co-localized measurements. The US on the other side is integrated with an acoustical reflector, which enables B-mode measurements on the same position as OCT and RS. The US B-mode scans can be translated across the sample by laterally moving the US transducer, which is made possible by the developed adapter with a flexible membrane. We present the results on custom-made liquid and agar phantoms that show the resolution and depth capabilities of the setup, as well as preliminary ex vivo measurements on mouse models with ∼4.3 mm thick melanoma.

Polarimetric techniques for the structural studies and diagnosis of brain

Abstract The polarimetric techniques are used in various biomedical applications for a non-contact and fast diagnosis of tissue that is known as optical biopsy approach. These optical modalities provide relevant information on micro-architecture of biological tissue and its alterations induced by different diseases, thus, helping in staging and precise delineation of the pathology zones. In this review, we summarize the work of different research groups on using polarized light for brain tissue studies. This includes the investigations of polarimetric properties of brain tissue (both scattering and optical anisotropy) for brain connectome reconstruction, the visualization of in-plane brain fiber tracts for brain tumor contrast enhancement during neurosurgery, and the histopathology analysis for disease staging in Alzheimer’s subjects. We discuss also further perspectives for the pre-clinical studies of brain with polarized light.

Real-time intraoperative surgical telepathology using confocal laser endomicroscopy.

Communication between neurosurgeons and pathologists is mandatory for intraoperative decision-making and optimization of resection, especially for invasive masses. Handheld confocal laser endomicroscopy (CLE) technology provides in vivo intraoperative visualization of tissue histoarchitecture at cellular resolution. The authors evaluated the feasibility of using an innovative surgical telepathology software platform (TSP) to establish real-time, on-the-fly remote communication between the neurosurgeon using CLE and the pathologist. CLE and a TSP were integrated into the surgical workflow for 11 patients with brain masses (6 patients with gliomas, 3 with other primary tumors, 1 with metastasis, and 1 with reactive brain tissue). Neurosurgeons used CLE to generate video-flow images of the operative field that were displayed on monitors in the operating room. The pathologist simultaneously viewed video-flow CLE imaging using a digital tablet and communicated with the surgeon while physically located outside the operating room (1 pathologist was in another state, 4 were at home, and 6 were elsewhere in the hospital). Interpretations of the still CLE images and video-flow CLE imaging were compared with the findings on the corresponding frozen and permanent H&E histology sections. Overall, 24 optical biopsies were acquired with mean ± SD 2 ± 1 optical biopsies per case. The mean duration of CLE system use was 1 ± 0.3 minutes/case and 0.25 ± 0.23 seconds/optical biopsy. The first image with identifiable histopathological features was acquired within 6 ± 0.1 seconds. Frozen sections were processed within 23 ± 2.8 minutes, which was significantly longer than CLE usage (p < 0.001). Video-flow CLE was used to correctly interpret tissue histoarchitecture in 96% of optical biopsies, which was substantially higher than the accuracy of using still CLE images (63%) (p = 0.005). When CLE is employed in tandem with a TSP, neurosurgeons and pathologists can view and interpret CLE images remotely and in real time without the need to biopsy tissue. A TSP allowed neurosurgeons to receive real-time feedback on the optically interrogated tissue microstructure, thereby improving cross-functional communication and intraoperative decision-making and resulting in significant workflow advantages over the use of frozen section analysis.

Optical biopsy for esophageal squamous cell neoplasia by using endocytoscopy

BackgroundEndocytoscopy (ECS) enables microscopic observation in vivo for the gastrointestinal mucosa; however, there has been no prospective study in which the diagnostic accuracy of ECS for lesions that have not yet undergone histological diagnosis was evaluated. We conducted a surveillance study for patients in a high-risk group of esophageal squamous cell carcinoma (ESCC) and evaluated the in vivo histological diagnostic accuracy of ECS.MethodsThis study was a multicenter prospective study. We enrolled 197 patients in the study between September 1, 2019 and November 30, 2020. The patients first underwent white light imaging and narrow band imaging, and ultra-high magnifying observation was performed if there was a lesion suspected to be an esophageal tumor. Endoscopic submucosal dissection (ESD) was later performed for lesions that were diagnosed to be ESCC by ECS without biopsy. We evaluated the diagnostic accuracy of ECS for esophageal tumorous lesions.ResultsESD was performed for 37 patients (41 lesions) who were diagnosed as having ESCC by ECS, and all of them were histopathologically diagnosed as having ESCC. The sensitivity [95% confidence interval (CI)] was 97.6% (87.7–99.7%), specificity (95% CI) was 100% (92.7–100%), diagnostic accuracy (95% CI) was 98.9% (94.0–99.8%), positive predictive value (PPV) (95% CI) was 100% (91.4–100%) and negative predictive value (NPV) (95% CI) was 98.0% (89.5–99.7%).ConclusionsECS has a high diagnostic accuracy and there were no false positives in cases diagnosed and resected as ESCC. Optical biopsy by using ECS for esophageal lesions that are suspected to be tumorous is considered to be sufficient in clinical practice.

Diagnostic accuracy of probe-based confocal laser endomicroscopy and tissue sampling by endoscopic retrograde cholangiopancreatography in indeterminate biliary strictures: a meta‑analysis

Probe-based confocal laser endomicroscopy (pCLE), also known as optical biopsy, is a new endoscopic technique that provides real-time magnification of 1000 × microscopic tissue information to diagnose indeterminate biliary strictures. Tissue sampling by endoscopic retrograde cholangiopancreatography (ERCP) is routinely performed to evaluate indeterminate biliary strictures. To evaluate the accuracy of pCLE and tissue sampling by ERCP in the diagnosis of indeterminate biliary strictures, 18 articles were included from 2008 to 2021 through Embase, PubMed, Web of Science, and Cochrane library databases. The summary estimates for the pCLE diagnosis of indeterminate biliary strictures were: sensitivity 0.88 (95% confidence interval (CI), 0.84–0.91); specificity 0.79 (95% CI 0.74–0.83); and Diagnostic Odds Ratio (DOR) 24.63 (95% CI 15.76–38.48). The summary estimates for tissue sampling by ERCP diagnosis for indeterminate biliary strictures were: sensitivity 0.54 (95% CI 0.49–0.59); specificity 0.96 (95% CI 0.94–0.98); and DOR 11.31 (95% CI 3.90–32.82). The area under the sROC curve of pCLE diagnosis of indeterminate biliary strictures is 0.90 higher than 0.65 of tissue sampling by ERCP. The pCLE is a better approach than tissue sampling by ERCP for the diagnosis of indeterminate biliary strictures by providing real-time microscopic images of the bile ducts.

P 71 Optical coherence tomography – a future imaging technique of peripheral nerves?

Object: Owing to their complex topography, their long courses and their small diameters peripheral nerves are challenging structures for radiological diagnostics. However, imaging techniques in the area of peripheral nerve diseases have undergone unexpected development in recent decades. They include magnetic-resonance imaging (MRI) and high-resolution sonography (HRS). Yet none of those imaging techniques reaches a resolution comparable to that of histological sections. Fascicles are the smallest discernable structure. Optical-coherence tomography (OCT) is the first imaging technique that is able to depict a nerve’s ultrastructure at micrometer resolution. Methods: OCT measurement was performed in 32 patients with different peripheral nerve pathologies, i.e. nerve compression syndromes. The nerves were examined during surgery after exposing. Only the sural nerve was twice examined ex vivo . The OCT systems Thorlabs Callisto and Thorlabs Ganymede were used. For intra-operative use, a hand probe was covered with a sterile foil. Different post-processing imaging techniques were applied and evaluated. Results: The intra-operative use of OCT is easy and intuitive. Image artifacts are mainly caused by motion and the sterile foil. If they are kept at a low level, the hyporeflecting bundles of nerve fascicles and their inner parts can be displayed. In the Haralick evaluation the second angular moment (SAM) is most suitable to depict the connective tissue. Conclusion: OCT is a new imaging technique which has shown to be promising in peripheral nerve surgery for particular questions. Its resolution exceeds that provided by recent radiological possibilities such as MRI and HRS. Since its field of view is relatively small, faster acquisition times would be highly desirable. Currently, the method resembles an optical biopsy and can be a supplement to intra-operative sonography, giving high-resolution insight into a suspect area which has been located by sonography in advance. This could be especially helpful in surgery of peripheral nerve lesions in continuity.