Use Of Laser Speckle Contrast Imaging Research Articles

Monitoring coronary blood flow by laser speckle contrast imaging after myocardial ischaemia reperfusion injury in adult and aged mice.

Investigating coronary microvascular perfusion responses after myocardial infarction (MI) would aid in the development of flow preserving therapies. Laser speckle contrast imaging (LSCI) is a powerful tool used for real-time, non-contact, full-field imaging of blood flow in various tissues/organs. However, its use in the beating heart has been limited due to motion artifacts. In this paper, we report the novel use of LSCI, combined with custom speckle analysis software (SpAn), to visualise and quantitate changes in ventricular perfusion in adult and aged mice undergoing ischaemia-reperfusion (IR) injury. The therapeutic benefit of inhibiting the actions of the pro-inflammatory cytokine interleukin-36 (IL-36) was also investigated using an IL-36 receptor antagonist (IL-36Ra). Imaging from uncovered and covered regions of the left ventricle demonstrated that whilst part of the LSCI flux signal was derived from beating motion, a significant contributor to the flux signal came from ventricular microcirculatory blood flow. We show that a biphasic flux profile corresponding to diastolic and systolic phases of the cardiac cycle can be detected without mathematically processing the total flux data to denoise motion artifacts. Furthermore, perfusion responses to ischaemia and postischaemia were strong, reproducible and could easily be detected without the need to subtract motion-related flux signals. LSCI also identified significantly poorer ventricular perfusion in injured aged mice following IR injury which markedly improved with IL-36Ra. We therefore propose that LSCI of the heart is possible despite motion artifacts and may facilitate future investigations into the role of the coronary microcirculation in cardiovascular diseases and development of novel therapies.

Laser Speckle Contrast Imaging Guides Needling Treatment of Vascular Complications from Dermal Fillers.

Although laser Doppler imaging (LDI) accurately delineates a hypoperfused area to help target hyaluronidase treatment, laser speckle contrast imaging (LSCI) is more appropriate for assessing microvascular hemodynamics and has greater reproducibility than LDI. This study investigated the use of LSCI in the evaluation and treatment of six patients who developed vascular complications after facial dermal filler injections. The areas of vascular occlusion were accurately defined in real time by LSCI and were more precise than visual inspections or photographic evidence for guiding needling and hyaluronidase treatment. All patients had achieved satisfactory outcomes as early as Day 2 of treatment and no procedure-related complications were reported after a median follow-up of 9.5 (7-37) days. LSCI accurately and noninvasively delineated vascular occlusions in real time among patients experiencing complications of facial dermal filler injections. Moreover, LSCI was more accurate than visual and photographic evaluations. Clinicians can use LSCI to reliably follow-up therapeutic outcomes after salvage interventions for vascular occlusions. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Blunted Microvascular Reactivity in Psoriasis Patients in the Absence of Cardiovascular Disease, as Assessed by Laser Speckle Contrast Imaging.

Psoriasis is associated with accelerated rates of cardiovascular disease (CVD). Laser Speckle Contrast Imaging (LSCI) is a novel, non-interventional technique for the dynamic assessment of microvascular endothelial dysfunction, which represents an early precursor of CVD. We investigated whether skin microvascular reactivity is impaired in psoriasis and whether an association exists with large artery stiffening. Skin microvascular reactivity was assessed with LSCI combined with post-occlusive reactive hyperaemia protocol in psoriasis patients and controls in the absence of established CVD. Arterial stiffness and central hemodynamics were assessed throughout a whole 24 h period with the Mobil-O-Graph device. Most LSCI indices of microvascular reactivity were impaired in psoriasis patients (n = 90) compared to controls (n = 45) [baseline flux; occlusion flux; peak-to-baseline magnitude; baseline cutaneous vascular conductance (CVC); percentage increase in CVC, p < 0.001 for all comparisons]. In multivariate analysis, psoriatic disease predicted the above markers independently of classical CVD risk factors. Augmentation index, peripheral pulse pressure, and central systolic/diastolic blood pressure correlated with LSCI microvascular responses in the study population (n = 135). Pulse wave velocity significantly correlated with nearly all LSCI parameters, while the association with baseline flux was independent of CVD risk factors and psoriatic disease in multivariate analysis (beta = 0.096, p = 0.039). This study provides evidence of altered skin microvascular responses in psoriasis by use of LSCI, and interaction with macrovascular dysfunction, before the establishment of overt CVD. A non-interventional approach of skin microcirculation with LSCI might be used as an early indicator of vascular health in psoriasis.

Real-time visualization of renal microperfusion using laser speckle contrast imaging.

.Significance: Intraoperative parameters of renal cortical microperfusion (RCM) have been associated with postoperative ischemia/reperfusion injury. Laser speckle contrast imaging (LSCI) could provide valuable information in this regard with the advantage over the current standard of care of being a non-contact and full-field imaging technique.Aim: Our study aims to validate the use of LSCI for the visualization of RCM on ex vivo perfused human-sized porcine kidneys in various models of hemodynamic changes.Approach: A comparison was made between three renal perfusion measures: LSCI, the total arterial renal blood flow (RBF), and sidestream dark-field (SDF) imaging in different settings of ischemia/reperfusion.Results: LSCI showed a good correlation with RBF for the reperfusion experiment (; ) and short- and long-lasting local ischemia (; and ; , respectively). The correlation decreased for low flow situations due to RBF redistribution. The correlation between LSCI and SDF (; ) showed superiority over RBF (; ).Conclusions: LSCI is capable of imaging RCM with high spatial and temporal resolutions. It can instantaneously detect local perfusion deficits, which is not possible with the current standard of care. Further development of LSCI in transplant surgery could help with clinical decision making.

Evidence Based Burn Depth Assessment Using Laser-Based Technologies: Where Do We Stand?

Early clinical assessment of burn depth and associated healing potential (HP) remains extremely challenging, even for experienced surgeons. Inaccurate diagnosis often leads to prolonged healing times and unnecessary surgical procedures, resulting in incremental costs, and unfavorable outcomes. Laser Doppler imaging (LDI) is currently the most objective and accurate diagnostic tool to measure blood flow and its associated HP, the main predictor for a patient's long-term functional and aesthetic outcome. A systematic review was performed on non-invasive, laser-based methods for burn depth assessment using skin microcirculation measurements to determine time to healing: Laser Doppler flowmetry (LDF), LDI and laser speckle contrast imaging (LSCI). Important drawbacks of single point LDF measurements are direct contact with numerous small points on the wound bed and the need to carry out serial measurements over several days. LDI is a fast, "non-contact," single measurement tool allowing to scan large burned areas with a 96% accuracy. LDI reduces the number of surgeries, improves the functional and aesthetic outcome and is cost-effective. There is only limited evidence for the use of LSCI in burn depth assessment. LSCI still needs technical improvements and scientific validation, before it can be approved for reliable burn assessment. LDI has proven to be invaluable in determining the optimal treatment of a burn patient. For unclear reasons, LDI is still not routinely used in burn centers worldwide. Additional research is required to identify potential "barriers" for universal implementation of this evidence-based burn depth assessment tool.

Laser speckle contrast imaging as a better tool to access the cutaneous microcirculation: Reproducibility and comparison to laser Doppler imaging in animal models

Current assessment of skin microcirculation function in animal models use laser Doppler flometry (LDF) or laser Doppler imaging (LDI). Both methods are limited by either low spatial resolution (LDF) or low temporal resolution (LDI). Laser speckle contrast imaging (LSCI) is a novel imaging technique of the cutaneous microcirculation with high spatial and temporal resolution. In this study, we report the use of LSCI in C57Bl/6 J mice in baseline flux, current induced vasodilation (CIV) and in wound healing monitoring (WHM) of excisionnal wound over 8 days. We describe the use of two high-resolution LSCI devices and compare them to LDI. To compare inter-day or/and inter-subject reproducibility of LSCI and LDI in CIV and WHM. Reproducibility will be expressed as coefficient of variation and intraclass coefficient correlation. Animal experiments were performed on 10-week-old C57Bl/6 J mice. CIV was produced by the administration of 100 μA of cathodal current over 4 min using a 1 cm 2 woven silver electrode with carboxymethylcellulose gel (Suprasorb G) as the electric diffusion layer. WHM was performed daily over 8 days after two 6 mm 2 wound were created on the back skin of the mice. Skin perfusion was assessed on the wound area and the periulcer skin. Both tested LSCI devices presented high resolution to 20 μm/pixel which allowed for the accurate mapping of the skin microcirculation in mice. Reproducibility data will be presented at the congress. LSCI is useful in assessing the cutaneous microcirculation compared to LDI. Additional testing is required such as skin microvascular reactivity to iontophoresis of acetylcholine and sodium nitroprusside and pressure ulcers for wound healing monitoring.

A new method for evaluating regional cerebral blood flow changes: Laser speckle contrast imaging in a C57BL/6J mouse model of photothrombotic ischemia.

The present study aimed to improve the processing of data acquired from laser speckle contrast imaging (LSCI) to provide a standardization method to explore changes in regional cerebral blood flow (rCBF) and to determine the correlations among rCBF, cerebral ischemic lesion volume and microvascular density over time in a focal ischemic region. C57BL/6J mice were subjected to focal photothrombotic (PT) ischemia. rCBF was measured using LSCI at different time points before and after PT ischemia through an intact skull. Standardized rCBF (SrCBF), defined as the ratio of rCBF measured in the ipsilateral region of interest (ROI) to that in the corresponding contralateral region, was calculated to evaluate potential changes. In addition, the volume of the ischemic lesion and the microvascular density were determined using Nissl staining and immunofluorescence, respectively. The relationships among the ischemic lesion volume, microvascular density and SrCBF were analyzed over time. The results showed that the cortical rCBF measured using LSCI following PT ischemia in the C57BL/6J mice gradually increased. Changes in the cerebral ischemic lesion volume were negatively correlated with SrCBF in the ischemic region. Changes in the microvascular density were similar to those observed in SrCBF. Our findings indicate that LSCI is a practical technique for observing changes in murine cortical rCBF without skull opening and for analyzing the relationships among the ischemic lesion volume, microvascular density and SrCBF following focal cerebral ischemia. Preliminary results also suggest that the use of LSCI to observe the formation of collateral circulation is feasible.

Longitudinalin vivomonitoring of rodent glioma models through thinned skull using laser speckle contrast imaging

Laser speckle contrast imaging (LSCI) is a contrast agent free imaging technique suited for longitudinal assessment of vascular remodeling that accompanies brain tumor growth. We report the use of LSCI to monitor vascular changes in a rodent glioma model. Ten rats are inoculated with 9L gliosarcoma cells, and the angiogenic response is monitored five times over two weeks through a thinned skull imaging window. We are able to visualize neovascularization and measure the number of vessels per unit area to assess quantitatively the microvessel density (MVD). Spatial spread of MVD reveals regions of high MVD that may correspond to tumor location. Whole-field average MVD values increase with time in the tumor group but are fairly stable in the control groups. Statistical analysis shows significant differences in MVD values between the tumor group and both saline-receiving and unperturbed control groups over the two-week period (p<0.05). In conclusion, LSCI is suitable for investigation of tumor angiogenesis in rodent models. In addition, the statistical difference (p<0.02) between MVD values of the tumor (24.40 ± 1.41) and control groups (15.40 ± 1.60) on the 14th day after inoculation suggests a potential use of LSCI in the clinic in distinguishing tumor environments from normal vasculature.