Mitigation of Motion Artifacts in Handheld Laser Speckle Contrast Imaging Illustrated on Psoriasis Lesions.

Background: Handheld laser speckle contrast imaging (LSCI) is crucial in clinical settings, but motion artifacts (MA) can compromise perfusion image reliability. Current prevention and suppression methods are often impractical or complex. Machine vision techniques, promising in medical imaging, could improve signal quality, but their use in suppressing MA is still unexplored.

Prediction of motion artifacts caused by translation in handheld laser speckle contrast imaging.

Significance: In handheld laser speckle contrast imaging (LSCI), motion artifacts (MA) are inevitable. Suppression of MA leads to a valid and objective assessment of tissue perfusion in a wide range of medical applications including dermatology and burns. Our study shines light on the sources of these artifacts, which have not yet been explored.

Imaging breast malignancies with the Twente Photoacoustic Mammoscope 2.

Clinical measurements on breast cancer patients were performed with a three-dimensional tomographic photoacoustic prototype imager (PAM 2). Patients with a suspicious lesion, visiting the center for breast care of a local hospital, were included in the study. The acquired photoacoustic images were compared to conventional clinical images.

Correction: Bulsink et al. Oxygen Saturation Imaging Using LED-Based Photoacoustic System. 2021, , 283.

The authors wish to make the following corrections to this paper [...

Self-synchronized reflection-mode acousto-optic imaging system utilizing nanosecond laser pulses.

We present an acousto-optic imaging system operating in reflection-mode and utilizing a pair of compact, triggerable lasers with 532 and 1064 nm wavelength and nanosecond pulse duration. The system maps the fluence rate distribution of light transmitted through optically scattering samples. The imaging is performed using an acousto-optic probe comprising an ultrasound linear array with attached optical fiber on one side and a camera on the other.

Perfusion measured by laser speckle contrast imaging as a predictor for expansion of psoriasis lesions.

Background: Skin microvasculature changes are crucial in psoriasis development and correlate with perfusion. The noninvasive Handheld Perfusion Imager (HAPI) examines microvascular skin perfusion in large body areas using laser speckle contrast imaging (LSCI).

Objectives: To (i) assess whether increased perilesional perfusion and perfusion inhomogeneity are predictors for expansion of psoriasis lesions and (ii) assess feasibility of the HAPI system in a mounted modality.

Assessment of flow within developing chicken vasculature and biofabricated vascularized tissues using multimodal imaging techniques.

Fluid flow shear stresses are strong regulators for directing the organization of vascular networks. Knowledge of structural and flow dynamics information within complex vasculature is essential for tuning the vascular organization within engineered tissues, by manipulating flows. However, reported investigations of vascular organization and their associated flow dynamics within complex vasculature over time are limited, due to limitations in the available physiological pre-clinical models, and the optical inaccessibility and aseptic nature of these models.

The Association between Foot and Ulcer Microcirculation Measured with Laser Speckle Contrast Imaging and Healing of Diabetic Foot Ulcers.

Diagnosis of peripheral artery disease in people with diabetes and a foot ulcer using current non-invasive blood pressure measurements is challenging. Laser speckle contrast imaging (LSCI) is a promising non-invasive technique to measure cutaneous microcirculation. This study investigated the association between microcirculation (measured with both LSCI and non-invasive blood pressure measurement) and healing of diabetic foot ulcers 12 and 26 weeks after measurement.

Reflection-mode acousto-optic imaging using plane wave ultrasound pulses.

Significance: Performance of an acousto-optic imaging system is limited by light fluence rate and acoustic pressure field distributions characteristics. In optically scattering media, the former determines the achievable contrast, whereas the latter the imaging resolution. The system parameters can be shaped by changing relative positions of ultrasound (US) transducer array and optodes.

Handheld versus mounted laser speckle contrast perfusion imaging demonstrated in psoriasis lesions.

Enabling handheld perfusion imaging would drastically improve the feasibility of perfusion imaging in clinical practice. Therefore, we examine the performance of handheld laser speckle contrast imaging (LSCI) measurements compared to mounted measurements, demonstrated in psoriatic skin. A pipeline is introduced to process, analyze and compare data of 11 measurement pairs (mounted-handheld LSCI modes) operated on 5 patients and various skin locations.

Pendant breast immobilization and positioning in photoacoustic tomographic imaging.

This work describes the design, development and added value of breast-supporting cups to immobilize and position the pendant breast in photoacoustic tomographic imaging. We explain the considerations behind the choice of the material, the shape and sizes of a cup-shaped construct for supporting the breast in water in an imaging tank during full-breast imaging. We provide details of the fabrication, and other processing and testing procedures used.

Oxygen Saturation Imaging Using LED-Based Photoacoustic System.

Oxygen saturation imaging has potential in several preclinical and clinical applications. Dual-wavelength LED array-based photoacoustic oxygen saturation imaging can be an affordable solution in this case. For the translation of this technology, there is a need to improve its accuracy and validate it against ground truth methods.

Semi-Automatic Tracking of Laser Speckle Contrast Images of Microcirculation in Diabetic Foot Ulcers.

Foot ulcers are a severe complication of diabetes mellitus. Assessment of the vascular status of diabetic foot ulcers with Laser Speckle Contrast Imaging (LSCI) is a promising approach for diagnosis and prognosis. However, manual assessment during analysis of LSCI limits clinical applicability.

Feasibility of identifying reflection artifacts in photoacoustic imaging using two-wavelength excitation.

One of the remaining challenges of bringing photoacoustic imaging to clinics is the occurrence of reflection artifacts. Previously, we proposed a method using multi-wavelength excitation to identify and remove the RAs. However, this method requires at least 3 wavelengths.

Reflection-mode acousto-optic imaging using a one-dimensional ultrasound array with electronically scanned focus.

Significance: Practical implementation of acousto-optic imaging (AOI) encounters difficulties that prevent it from rapid adoption in clinical use. In many practical medical applications, the region of interest may be accessed only from one side, and using a water tank for coupling is not feasible. The solution might be to use reflection-mode imaging with an electronically scanned ultrasound (US) focus.

Exploration of movement artefacts in handheld laser speckle contrast perfusion imaging.

Functional performance of handheld laser speckle contrast imaging (LSCI) is compromised by movement artefacts. Here we quantify the movements of a handheld LSCI system employing electromagnetic (EM) tracking and measure the applied translational, tilt and on-surface laser beam speeds. By observing speckle contrast on static objects, the magnitudes of translation and tilt of wavefronts are explored for various scattering levels of the objects.

Tomographic Ultrasound and LED-Based Photoacoustic System for Preclinical Imaging.

Small animals are widely used as disease models in medical research. Noninvasive imaging modalities with functional capability play an important role in studying the disease state and treatment progress. Photoacoustics, being a noninvasive and functional modality, has the potential for small-animal imaging.

Tomographic imaging with an ultrasound and LED-based photoacoustic system.

Pulsed lasers in photoacoustic tomography systems are expensive, which limit their use to a few clinics and small animal labs. We present a method to realize tomographic ultrasound and photoacoustic imaging using a commercial LED-based photoacoustic and ultrasound system. We present two illumination configurations using LED array units and an optimal number of angular views for tomographic reconstruction.

Dependency of the optical scattering properties of human milk on casein content and common sample preparation methods.

Significance: Quantifying human milk composition is important for daily nutritional management in neonatal intensive cares worldwide. Photonic solutions based on visible light can potentially aid in this analysis, as energy content of human milk depends largely on fat content, and the optical scattering properties of human milk predominantly depend on the size and concentration of fat globules. However, it is expected that human milk scattering changes upon homogenization, routinely done before analysis, which may affect fat globule size.

Three-dimensional view of out-of-plane artifacts in photoacoustic imaging using a laser-integrated linear-transducer-array probe.

Research on photoacoustic imaging (PAI) using a handheld integrated photoacoustic probe has been a recent focus of clinical translation of this imaging technique. One of the remaining challenges is the occurrence of out-of-plane artifacts (OPAs) in such a probe. Previously, we proposed a method to identify and remove OPAs by axially displacing the transducer array.

Twente Photoacoustic Mammoscope 2: system overview and three-dimensional vascular network images in healthy breasts.

We present the Twente Photoacoustic Mammoscope 2, a photoacoustic breast imaging system employing a tomographic configuration. It images one breast pendant inside an imaging tank filled with water while a woman lies prone on a bed. A dual-head laser (755 and 1064 nm) illuminates the breast with one beam directed at the nipple and nine beams directed at the sides.

Quantification of total haemoglobin concentrations in human whole blood by spectroscopic visible-light optical coherence tomography.

The non-invasive quantification of total haemoglobin concentrations [tHb] is highly desired for the assessment of haematologic disorders in vulnerable patient groups, but invasive blood sampling is still the gold standard in current clinical practice. This work demonstrates the potential of visible-light spectroscopic optical coherence tomography (sOCT) for quantifying the [tHb] in human whole blood. To accurately quantify the [tHb] from the substantial optical attenuation by blood in the visible wavelength range, we used a combination of zero-delay acquisition and focus tracking that ensures optimal system sensitivity at any depth inside the sample.

Reducing artifacts in photoacoustic imaging by using multi-wavelength excitation and transducer displacement.

The occurrence of artifacts is a major challenge in photoacoustic imaging. The artifacts negatively affect the quality and reliability of the images. An approach using multi-wavelength excitation has previously been reported for in-plane artifact identification.