. Significance : Multi-laboratory initiatives are essential in performance assessment and standardization—crucial for bringing biophotonics to mature clinical use—to establish protocols and develop reference tissue phantoms that all will allow universal instrument comparison. Aim : The largest multi-laboratory comparison of performance assessment in near-infrared diffuse optics is presented, involving 28 instruments and 12 institutions on a total of eight experiments based on three consolidated protocols (BIP, MEDPHOT, and NEUROPT) as implemented on three kits of tissue phantoms. A total of 20 synthetic indicators were extracted from the dataset, some of them defined here anew. Approach : The exercise stems from the Innovative Training Network BitMap funded by the European Commission and expanded to include other European laboratories. A large variety of diffuse optics instruments were considered, based on different approaches (time domain/frequency domain/continuous wave), at various stages of maturity and designed for different applications (e.g., oximetry, spectroscopy, and imaging). Results : This study highlights a substantial difference in hardware performances (e.g., nine decades in responsivity, four decades in dark count rate, and one decade in temporal resolution). Agreement in the estimates of homogeneous optical properties was within 12% of the median value for half of the systems, with a temporal stability of over 1 h, and day-to-day reproducibility of . Other tests encompassed linearity, crosstalk, uncertainty, and detection of optical inhomogeneities. Conclusions : This extensive multi-laboratory exercise provides a detailed assessment of near-infrared Diffuse optical instruments and can be used for reference grading. The dataset—available soon in an open data repository—can be evaluated in multiple ways, for instance, to compare different analysis tools or study the impact of hardware implementations.

Background Single snapshot imaging of optical properties (SSOP) is a relatively new non-invasive, real-time, contrast-free optical imaging technology, which allows for the real-time quantitative assessment of physiological properties, including tissue oxygenation (StO2). This study evaluates the accuracy of multispectral SSOP in quantifying bowel ischaemia in a preclinical experimental model. Methods In six pigs, an ischaemic bowel segment was created by dividing the arcade branches. Five regions of interest (ROIs) were identified on the bowel loop, as follows: ROI 1: central ischaemic; ROI 2: left marginal; ROI 3: left vascularised; ROI 4: right marginal; and ROI 5: right vascularised. The Trident imaging system, specifically developed for real-time tissue oxygenation imaging using SSOP, was used to image before (T0) and after ischaemia induction. Capillary and systemic lactates were measured at each time point (T0, T15, T30, T45, T60), as well as StO2 values acquired by means of SSOP (SSOP-StO2). Results The mean value of SSOP-StO2 in ROI 1 was 30.08 ± 6.963 and was significantly lower when compared to marginal ROIs (ROI 2 + ROI 4: 45.67 ± 10.02 p =  < 0.0001), and to vascularised ROIs (ROI 3 + ROI 5: 48.08 ± 7.083 p =  < 0.0001). SSOP-StO2 was significantly correlated with normalised lactates r = − 0.5892 p < 0.0001 and with histology r =− 0.6251 p = 0.0002. Conclusion Multispectral SSOP allows for a contrast-free accurate assessment of small bowel perfusion identifying physiological tissue oxygenation as confirmed with perfusion biomarkers.

Performance assessment and standardization are indispensable for instruments of clinical relevance in general and clinical instrumentation based on photon migration/diffuse optics in particular. In this direction, a multi-laboratory exercise was initiated with the aim of assessing and comparing their performances. 29 diffuse optical instruments belonging to 11 partner institutions of a European level Marie Curie Consortium BitMap 1 were considered for this exercise. The enrolled instruments covered different approaches (continuous wave, CW; frequency domain, FD; time domain, TD and spatial frequency domain imaging, SFDI) and applications (e.g. mammography, oximetry, functional imaging, tissue spectroscopy). 10 different tests from 3 well-accepted protocols, namely, the MEDPHOT 2 , the BIP 3 , and the nEUROPt 4 protocols were chosen for the exercise and the necessary phantoms kits were circulated across labs and institutions enrolled in the study. A brief outline of the methodology of the exercise is presented here. Mainly, the design of some of the synthetic descriptors, (single numeric values used to summarize the result of a test and facilitate comparison between instruments) for some of the tests will be discussed.. Future actions of the exercise aim at deploying these measurements onto an open data repository and investigating common analysis tools for the whole dataset.

Anastomotic leakage (AL) is a serious complication occurring after esophagectomy. The current knowledge suggests that inadequate intraoperative perfusion in the anastomotic site contributes to an increase in the AL rate. Presently, clinical estimation undertaken by surgeons is not accurate and new technology is necessary to improve the intraoperative assessment of tissue oxygenation. In the present study, we demonstrate the application of a novel optical technology, namely Single Snapshot imaging of Optical Properties (SSOP), used to quantify StO2% in an open surgery experimental gastric conduit (GC) model. After the creation of a gastric conduit, local StO2% was measured with a preclinical SSOP system for 60 min in the antrum (ROI-A), corpus (ROI-C), and fundus (ROI-F). The removed region (ROI-R) acted as ischemic control. ROI-R had statistically significant lower StO2% when compared to all other ROIs at T15, T30, T45, and T60 (p < 0.0001). Local capillary lactates (LCLs) and StO2% correlation was statistically significant (R = −0.8439, 95% CI −0.9367 to −0.6407, p < 0.0001). Finally, SSOP could discriminate resected from perfused regions and ROI-A from ROI-F (the future anastomotic site). In conclusion, SSOP could well be a suitable technology to assess intraoperative perfusion of GC, providing consistent StO2% quantification and ROIs discrimination.