Near-infrared diffuse optical characterization of human thyroid using ultrasound-guided hybrid time-domain and diffuse correlation spectroscopies.

Thyroid vascularization and hemodynamics become altered in thyroid pathologies and could thus inform diagnostics, therapy planning, and follow-up. However, the current non-invasive monitoring methods available in clinics lack the necessary sensitivity and/or are impractical for large-scale deployment. As a step towards proposing a new modality, we applied the first platform, to our knowledge, designed to do simultaneous measurements of neck anatomy and thyroid microvascular hemodynamics and metabolism in a single probe placement, integrating state-of-the-art near-infrared spectroscopy techniques and clinical ultrasound.

High throughput compressive fluorescence lifetime imaging with a silicon photomultiplier detector.

Fluorescence lifetime imaging microscopy (FLIM) is a powerful technique for studying biological processes. There exists a growing interest in developing strategies to enhance throughput and reduce acquisition time of FLIM systems, which commonly employ laser scanning excitation and time-correlated single-photon counting (TCSPC) detection. In this work, we propose a wide-field FLIM microscope based on compressive sensing and high photon rate detection (beyond pile-up limit) based on a high-efficiency silicon photomultiplier detector as a single-pixel camera.

Initial non-invasive in vivo sensing of the lung using time domain diffuse optics.

The in vivo diagnosis and monitoring of pulmonary disorders (caused for example by emphysema, Covid-19, immature lung tissue in infants) could be effectively supported by the non-invasive sensing of the lung through light. With this purpose, we investigated the feasibility of probing the lung by means of time-resolved diffuse optics, leveraging the increased depth (a few centimeters) attained by photons collected after prolonged propagation time (a few nanoseconds). We present an initial study that includes measurements performed on 5 healthy volunteers during a breathing protocol, using a time-resolved broadband diffuse optical spectroscopy system.

Quality Characteristics, Sensory Profiles and Ethylene Production of Stored 'Abate Fetel' Pears Sorted at Harvest by Time-Resolved Reflectance Spectroscopy.

Time-resolved reflectance spectroscopy (TRS), a nondestructive technique, can help the industry to provide high-quality fruit to encourage pear consumption. The absorption coefficient measured by TRS at 670 nm (670) represents a maturity index for pear fruit, with less mature pears high 670 and more mature low 670. The aim of this work was to study the quality characteristics, the sensory profiles and the ethylene production of 'Abate Fetel' pears sorted at harvest in different TRS maturity classes and stored in different atmospheres.

characterization of the optical and hemodynamic properties of the human sternocleidomastoid muscle through ultrasound-guided hybrid near-infrared spectroscopies.

In this paper, we present a detailedcharacterization of the optical and hemodynamic properties of the human sternocleidomastoid muscle (SCM), obtained through ultrasound-guided near-infrared time-domain and diffuse correlation spectroscopies.A total of sixty-five subjects (forty-nine females, sixteen males) among healthy volunteers and thyroid nodule patients have been recruited for the study. Their SCM hemodynamic (oxy-, deoxy- and total hemoglobin concentrations, blood flow, blood oxygen saturation and metabolic rate of oxygen extraction) and optical properties (wavelength dependent absorption and reduced scattering coefficients) have been measured by the use of a novel hybrid device combining in a single unit time-domain near-infrared spectroscopy, diffuse correlation spectroscopy and simultaneous ultrasound imaging.

Multi-laboratory performance assessment of diffuse optics instruments: the BitMap exercise.

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.

Effects and correctability of pile-up distortion using established figures of merit in time-domain diffuse optics at extreme photon rates.

Time-domain diffuse optics (TD-DO) allows one to probe diffusive media with recognized advantages over other working domains but suffers from a poor signal-to-noise ratio (SNR) resulting from the need to build-up the histogram of single-photon arrival times with maximum count rates (CR) of few percent of the laser pulse rate to avoid the so-called "pile-up" distortion. Here we explore the feasibility of TD-DO under severe pile-up conditions with a systematic in-silico/experimental study evaluating the effects and correctability of the distortion by means of shared figures of merit. In-silico, we demonstrate that pile-up correction allows one the retrieval of homogeneous optical properties with average error < 1% up to a CR > 99%, while the optimal CR needed to detect localized perturbation was found to be 83%.

Evaluation of a pipeline for simulation, reconstruction, and classification in ultrasound-aided diffuse optical tomography of breast tumors.

Significance: Diffuse optical tomography is an ill-posed problem. Combination with ultrasound can improve the results of diffuse optical tomography applied to the diagnosis of breast cancer and allow for classification of lesions.

Aim: To provide a simulation pipeline for the assessment of reconstruction and classification methods for diffuse optical tomography with concurrent ultrasound information.

The LUCA device: a multi-modal platform combining diffuse optics and ultrasound imaging for thyroid cancer screening.

We present the LUCA device, a multi-modal platform combining eight-wavelength near infrared time resolved spectroscopy, sixteen-channel diffuse correlation spectroscopy and a clinical ultrasound in a single device. By simultaneously measuring the tissue hemodynamics and performing ultrasound imaging, this platform aims to tackle the low specificity and sensitivity of the current thyroid cancer diagnosis techniques, improving the screening of thyroid nodules. Here, we show a detailed description of the device, components and modules.

Recipes for diffuse correlation spectroscopy instrument design using commonly utilized hardware based on targets for signal-to-noise ratio and precision.

Over the recent years, a typical implementation of diffuse correlation spectroscopy (DCS) instrumentation has been adapted widely. However, there are no detailed and accepted recipes for designing such instrumentation to meet pre-defined signal-to-noise ratio (SNR) and precision targets. These require specific attention due to the subtleties of the DCS signals.

Orthopedic screws insertion simulation with immediate feedback enhances surgical skill.

Background: Screw insertion to bones is a fundamental skill in orthopedic, spine and cranio-maxillofacial surgery. Applying the correct tightening torque is critical when compressing and fixating bone fragments. Overtightening yields in plastic deformation of the bone and destruction of the screw-bone interface, damaging the construct's stability.

Time resolved speckle contrast optical spectroscopy at quasi-null source-detector separation for non-invasive measurement of microvascular blood flow.

Time (or path length) resolved speckle contrast optical spectroscopy (TD-SCOS) at quasi-null (2.85 mm) source-detector separation was developed and demonstrated. The method was illustrated by studies on the forearm muscle of an adult subject.

test-driven upgrade of a time domain multi-wavelength optical mammograph.

A recent upgrade of the time domain multi-wavelength optical mammograph developed by Politecnico di Milano achieved good performance in laboratory tests [Biomed. Opt. Express9, 755 (2018).

Monitoring the motor cortex hemodynamic response function in freely moving walking subjects: a time-domain fNIRS pilot study.

This study is a preliminary step toward the identification of a noninvasive and reliable tool for monitoring the presence and progress of gaiting dysfunctions. We present the results of a pilot study for monitoring the motor cortex hemodynamic response function (HRF) in freely walking subjects, with time-domain functional near-infrared spectroscopy (TD fNIRS). A compact and wearable single-channel TD fNIRS oximeter was employed.

Is initial interfragmentary compression made to last? An ovine bone in vitro study.

Interfragmentary compression, a major principle of fracture treatment, is clinically not quantified and might be lost quickly even without functional loads. We designed an experimental study hypothesizing that (1) compression can be controlled using either lag screw or compression plate, and expecting similar initial compression, (2) loss of interfragmentary compression through relaxation within one hour is reduced with neutralization locking plate next to lag screw compared to compression plate. Twelve ovine femora (N=6) and humeri (N=6) were assigned into groups: Group 1 received a 45° oblique osteotomy at mid-diaphysis and was fixated using a 3.

Wearable and wireless time-domain near-infrared spectroscopy system for brain and muscle hemodynamic monitoring.

We present a wearable time-domain near infrared spectroscopy (TD-NIRS) system (two wavelengths, one detection channel), which fits in a backpack and performs real-time hemodynamic measurements on the brain and muscle tissues of freely moving subjects. It can provide concentration values of oxygenated hemoglobin (OHb), deoxygenated hemoglobin (HHb), total hemoglobin (tHb = OHb + HHb) and tissue oxygen saturation (StO). The system is battery-operated and can be wirelessly controlled.

Real-Time Dual-Wavelength Time-Resolved Diffuse Optical Tomography System for Functional Brain Imaging Based on Probe-Hosted Silicon Photomultipliers.

Near-infrared diffuse optical tomography is a non-invasive photonics-based imaging technology suited to functional brain imaging applications. Recent developments have proved that it is possible to build a compact time-domain diffuse optical tomography system based on silicon photomultipliers (SiPM) detectors. The system presented in this paper was equipped with the same eight SiPM probe-hosted detectors, but was upgraded with six injection fibers to shine the sample at several points.

Histamine H Receptors Expressed in Ventral Horns Modulate Spinal Motor Output.

Motoneuron activity is modulated by histamine receptors. While H and H receptors have been widely explored, H histamine receptors (HRs) have not been sufficiently characterized. This paper targets the effects of the selective activation of HRs and their expression on the membranes of large ventral horn cells.

Systematic study of the effect of ultrasound gel on the performances of time-domain diffuse optics and diffuse correlation spectroscopy.

Recently, multimodal imaging has gained an increasing interest in medical applications thanks to the inherent combination of strengths of the different techniques. For example, diffuse optics is used to probe both the composition and the microstructure of highly diffusive media down to a depth of few centimeters, but its spatial resolution is intrinsically low. On the other hand, ultrasound imaging exhibits the higher spatial resolution of morphological imaging, but without providing solid constitutional information.

Effects of the instrument response function and the gate width in time-domain diffuse correlation spectroscopy: model and validations.

Time-domain diffuse correlation spectroscopy (TD-DCS) is an emerging noninvasive optical technique with the potential to resolve blood flow (BF) and optical coefficients (reduced scattering and absorption) in depth. Here, we study the effects of finite temporal resolution and gate width in a realistic TD-DCS experiment. We provide a model for retrieving the BF from gated intensity autocorrelations based on the instrument response function, which allows for the use of broad time gates.

Instrumental, optical and geometrical parameters affecting time-gated diffuse optical measurements: a systematic study.

In time-domain diffuse optics the sensitivity to localized absorption changes buried inside a diffusive medium depends strongly on the interplay between instrumental, optical and geometrical parameters, which can hinder the theoretical advantages of novel measurement strategies like the short source-detector distance approach. Here, we present a study based on experimental measurements and simulations to comprehensively evaluate the effect of all different parameters. Results are evaluated exploiting standardized figures of merit, like contrast and contrast-to-noise ratio, to quantify the system sensitivity to deep localized absorption perturbations.

Broadband (550-1350 nm) diffuse optical characterization of thyroid chromophores.

Thyroid plays an important role in the endocrine system of the human body. Its characterization by diffuse optics can open new path ways in the non-invasive diagnosis of thyroid pathologies. Yet, the absorption spectra of tyrosine and thyroglobulin-key tissue constituents specific to the thyroid organ-in the visible to near infrared range are not fully available.