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Introduction: Anastomotic leakage after gastrointestinal surgery has a high impact on patient's quality of life and its origin is associated with inadequate perfusion. Imaging photoplethysmography (iPPG) is a noninvasive imaging technique that measures blood-volume changes in the microvascular tissue bed and detects changes in tissue perfusion., Materials and Methods: Intraoperative iPPG imaging was performed in 29 patients undergoing an open segment resection of the small intestine or colon. During each surgery, imaging was performed on fully perfused (true positives) and ischemic intestines (true negatives) and the anastomosis (unknowns). Imaging consisted of a 30-s video from which perfusion maps were extracted, providing detailed information about blood flow within the intestine microvasculature. To detect the predictive capabilities of iPPG, true positive and true negative perfusion conditions were used to develop two different perfusion classification methods., Results: iPPG-derived perfusion parameters were highly correlated with perfusion-perfused or ischemic-in intestinal tissues. A perfusion confidence map distinguished perfused and ischemic intestinal tissues with 96% sensitivity and 86% specificity. Anastomosis images were scored as adequately perfused in 86% of cases and 14% inconclusive. The cubic-Support Vector Machine achieved 90.9% accuracy and an area under the curve of 96%. No anastomosis-related postoperative complications were encountered in this study., Conclusions: This study shows that noninvasive intraoperative iPPG is suitable for the objective assessment of small intestine and colon anastomotic perfusion. In addition, two perfusion classification methods were developed, providing the first step in an intestinal perfusion prediction model., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Background: Careful identification of nerves during head and neck surgery is essential to prevent nerve damage. Currently, nerves are identified based on anatomy and appearance, optionally combined with electromyography (EMG). In challenging cases, nerve damage is reported in up to 50%. Recently, optical techniques, like diffuse reflectance spectroscopy (DRS) and fluorescence spectroscopy (FS) show potential to improve nerve identification., Methods: 212 intra-operative DRS/FS measurements were performed. Small nerve branches (1-3 mm), on near-nerve adipose tissue, muscle and subcutaneous fat were measured during 11 surgical procedures. Tissue identification was based on quantified concentrations of optical absorbers and scattering parameters., Results: Clinically comprehensive parameters showed significant differences (<0.05) between the tissues. Classification using k-Nearest Neighbor resulted in 100% sensitivity and a specificity of 83% (accuracy 91%), for the identification of nerve against surrounding tissues., Conclusions: DRS/FS is a potentially useful intraoperative tool for identification of nerves from adjacent tissues., Level of Evidence: Observational proof of principle study.

Objective: Identification of peripheral nerve tissue is crucial in both surgery and regional anesthesia. Recently, optical tissue identification methods are presented to facilitate nerve identification in transcutaneous procedures and surgery. Optimization and validation of such techniques require large datasets. The use of alternative models to human in vivo, like human post mortem, or swine may be suitable to test, optimize and validate new optical techniques. However, differences in tissue characteristics and thus optical properties, like oxygen saturation and tissue perfusion are to be expected. This requires a structured comparison between the models., Study Design: Comparative observational study., Methods: Nerve and surrounding tissues in human (in vivo and post mortem) and swine (in vivo and post mortem) were structurally compared macroscopically, histologically, and spectroscopically. Diffuse reflective spectra were acquired (400-1,600 nm) after illumination with a broad band halogen light. An analytical model was used to quantify optical parameters including concentrations of optical absorbers., Results: Several differences were found histologically and in the optical parameters. Histologically nerve and adipose tissue (subcutaneous fat and sliding fat) showed clear similarities between human and swine while human muscle enclosed more adipocytes and endomysial collagen. Optical parameters revealed model dependent differences in concentrations of β-carotene, water, fat, and oxygen saturation. The similarity between optical parameters is, however, sufficient to yield a strong positive correlation after cross model classification., Conclusion: This study shows and discusses similarities and differences in nerve and surrounding tissues between human in vivo and post mortem, and swine in vivo and post mortem; this could support the discussion to use an alternative model to optimize and validate optical techniques for clinical nerve identification. Lasers Surg. Med. 50:253-261, 2018. © 2017 Wiley Periodicals, Inc., (© 2017 Wiley Periodicals, Inc.)

Background and Objective: Over the last decade, an increasing effort has been put towards the implementation of optical guidance techniques to aid surgeons during cancer surgery. Diffuse reflectance spectroscopy (DRS) and fluorescence spectroscopy (FS) are two of these new techniques. The objective of this study is to investigate whether in vivo optical spectroscopy is able to accurately discriminate colorectal liver metastases (CRLM) from normal liver tissue in vivo., Materials and Methods: DRS and FS were incorporated at the tip of a needle and were used for in vivo tissue differentiation during resection of CRLM. Measurements were taken in and around the tumor lesions and measurement sites were marked and correlated to histology (i.e., normal liver tissue or tumor tissue). Patients with and without neoadjuvant systemic chemotherapy were included into the study., Results: Four hundred and eighty-four measurements were taken in and near 19 liver lesions prior to resection. Overall sensitivity and specificity for DRS was 95% and 92%, respectively. Bile was the most discriminative parameter. The addition of FS did not improve the overall accuracy. Sensitivity and specificity was not hampered by neo-adjuvant chemotherapy; sensitivity and specificity after neo-adjuvant chemotherapy were 92% and 100%, respectively., Conclusion: We have successfully integrated spectroscopy technology into a disposable 15 Gauge optical needle and we have shown that DRS and FS can accurately discriminate CRLM from normal liver tissue in the in vivo setting regardless of whether the patient was pre-treated with systemic therapy. This technique makes in vivo guidance accessible for common surgical practice. Lasers Surg. Med. 48:820-827, 2016. © 2016 Wiley Periodicals, Inc., (© 2016 Wiley Periodicals, Inc.)

Objectives: Difficulties in obtaining a representative tissue sample are a major obstacle in timely selecting the optimal treatment for patients with lung cancer or other malignancies. Having a modality to provide needle guidance and confirm the biopsy site selection could be of great clinical benefit, especially when small masses are targeted. The objective of this study was to evaluate whether diffuse reflectance spectroscopy (DRS) at the tip of a core biopsy needle can be used for biopsy site confirmation in real time, thereby enabling optimized biopsy acquisition and improving diagnostic capability., Materials and Methods: We included a total of 23 patients undergoing a routine computed tomography (CT) guided transthoracic needle biopsy of a lesion suspected for lung cancer or metastatic disease. DRS measurements were acquired during needle insertion and clinically relevant parameters were extracted from the spectral data along the needle paths. Histopathology results were compared with the DRS data at the final measurement position., Results: Analysis of the collective data acquired from all enrolled subjects showed significant differences (p<0.01) for blood content, stO2, water content, and scattering amplitude. The identified spectral contrast matched the final pathology in 20 out of 22 clinical cases that could be used for analysis, which corresponds with an overall diagnostic performance of 91%. Three cases underlined the importance of adequate reference measurements and the need for real time diagnostic feedback. Continuous real time DRS measurements performed during a biopsy procedure in one patient provided clear information with respect to the variation in tissue and allowed identification of the tumour boundary., Conclusions: The presented technology creates a basis for the design and clinical implementation of integrated fibre-optic tools for a variety of minimal invasive applications., (Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.)

Purpose: This study presents the first in vivo real-time tissue characterization during image-guided percutaneous lung biopsies using diffuse reflectance spectroscopy (DRS) sensing at the tip of a biopsy needle with integrated optical fibers., Experimental Design: Tissues from 21 consented patients undergoing lung cancer surgery were measured intraoperatively using the fiber-optic platform capable of assessing various physical tissue properties highly correlated to tissue architecture and composition. In addition, the method was tested for clinical use by performing DRS tissue sensing during 11 routine biopsy procedures in patients with suspected lung cancer., Results: We found that water content and scattering amplitude are the primary discriminators for the transition from healthy lung tissue to tumor tissue and that the reliability of these parameters is not affected by the amount of blood at the needle tip. In the 21 patients measured intraoperatively, the water-to-scattering ratio yielded a 56% to 81% contrast difference between tumor and surrounding tissue. Analysis of the 11 image-guided lung biopsy procedures showed that the tissue diagnosis derived from DRS was diagnostically discriminant in each clinical case., Conclusions: DRS tissue sensing integrated into a biopsy needle may be a powerful new tool for biopsy guidance that can be readily used in routine diagnostic lung biopsy procedures. This approach may not only help to increase the successful biopsy yield for histopathologic analysis, but may also allow specific sampling of vital tumor tissue for genetic profiling., (©2015 American Association for Cancer Research.)

Introduction: Anatomic imaging alone is often inadequate for tuning systemic treatment for individual tumor response. Optically based techniques could potentially contribute to fast and objective response monitoring in personalized cancer therapy. In the present study, we evaluated the feasibility of dual-modality diffuse reflectance spectroscopy-autofluorescence spectroscopy (DRS-AFS) to monitor the effects of systemic treatment in a mouse model for hereditary breast cancer., Methods: Brca1(-/-); p53(-/-) mammary tumors were grown in 36 mice, half of which were treated with a single dose of cisplatin. Changes in the tumor physiology and morphology were measured for a period of 1 week using dual-modality DRS-AFS. Liver and muscle tissues were also measured to distinguish tumor-specific alterations from systemic changes. Model-based analyses were used to derive different optical parameters like the scattering and absorption coefficients, as well as sources of intrinsic fluorescence. Histopathologic analysis was performed for cross-validation with trends in optically based parameters., Results: Treated tumors showed a significant decrease in Mie-scattering slope and Mie-to-total scattering fraction and an increase in both fat volume fraction and tissue oxygenation after 2 days of follow-up. Additionally, significant tumor-specific changes in the fluorescence spectra were seen. These longitudinal trends were consistent with changes observed in the histopathologic analysis, such as vital tumor content and formation of fibrosis., Conclusions: This study demonstrates that dual-modality DRS-AFS provides quantitative functional information that corresponds well with the degree of pathologic response. DRS-AFS, in conjunction with other imaging modalities, could be used to optimize systemic cancer treatment on the basis of early individual tumor response., (Copyright © 2014 Neoplasia Press, Inc. Published by Elsevier Inc. All rights reserved.)

Introduction: A significant number of transthoracic diagnostic biopsy procedures for lung lesions show indeterminate results. Such failures are potentially due to inadequate recognition of vital tumor tissue. The objective of this study was to evaluate whether optical spectroscopy at the tip of a biopsy needle device can improve the accuracy of transthoracic lung biopsies., Methods: Ex vivo optical measurements were performed on lung tissue from 13 patients who underwent either lobectomy or segmental resection for primary non-small cell lung cancer or pulmonary metastases from various origins. From Diffuse Reflectance Spectroscopy (DRS) and Fluorescence Spectroscopy (FS) measurements, different parameters were derived such as tissue composition as well as physiological and metabolic characteristics. Subsequently, a classification and regression trees (CART) algorithm was used to classify the type of tissue based on the derived parameters. Histology analysis was used as gold standard to report sensitivity and specificity of the tissue classification based on the present optical method., Results: Collective analysis of all DRS measurements showed an overall discrimination between lung parenchyma and tumor tissue with a sensitivity and specificity of 98 and 86%, respectively. When the data were analyzed per individual patient, eliminating inter-patient variation, 100% sensitivity and specificity was achieved. Furthermore, based on FS parameters, necrotic and non-necrotic tumor tissue could be distinguished with 91% sensitivity and specificity., Conclusion: This study demonstrates that DRS provides accurate diagnosis of malignant lung lesions, whereas FS enables identification of necrotic tissue. When both optical techniques are combined within a biopsy device, the diagnostic performance and the quality of transthoracic biopsies could significantly be enhanced., (Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.)

Background: A significant number of percutaneous intrathoracic biopsy procedures result in indeterminate cytologic or histologic diagnosis in clinical practice. Diffuse reflectance spectroscopy (DRS) is an optical technique that can distinguish different tissue types on a microscopic level. DRS may improve needle localization accuracy during biopsy procedures. The objective of this study was to assess the ability of DRS to enhance diagnosis of malignant disease in human lung tissue., Methods: Ex vivo analysis with a DRS system was performed on lung tissue from 10 patients after pulmonary resection for malignant disease. Tissue spectra measured from 500 to 1600 nm were analyzed using 2 analysis methods; a model-based analysis that derives clinical and optical properties from the measurements and a partial least-squares discriminant analysis (PLS-DA) that classifies measured spectra with respect to the histologic nature of the measured tissue., Results: Sensitivity and specificity for discrimination of tumor from normal lung tissue were 89% and 79%, respectively, based on the model-based analysis. Overall accuracy was 84%. The PLS-DA analysis yielded a sensitivity of 78%, a specificity of 86%, and an overall accuracy of 81%., Conclusions: The presented results demonstrate that DRS has the potential to enhance diagnostic accuracy in minimally invasive biopsy procedures in the lungs in combination with conventional imaging techniques., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Epidural injection is commonly used to provide intraoperative anesthesia, postoperative and obstetric analgesia, and to treat acute radicular pain. Identification of the epidural space is typically carried out using the loss of resistance (LOR) technique, but the usefulness of this technique is limited by false LOR and the inability to reliably detect intravascular or subarachnoid needle placement. In this study, we present a novel epidural needle that allows for the acquisition of optical reflectance spectra from tissue close to the beveled surface. This needle has optical fibers embedded in the cannula that deliver and receive light. With two spectrometers, light received from tissue is resolved across the wavelength range of 500 to 1600 nm. To determine the feasibility of optical tissue differentiation, spectra were acquired from porcine tissues during a post mortem laminectomy. The spectra were processed with an algorithm that derives estimates of the hemoglobin and lipid concentrations. The results of this study suggest that the optical epidural needle has the potential to improve the accuracy of epidural space identification.