Speckle Analysis Research Articles

A Strain-Based Staging Classification of Left Bundle Branch Block-Induced Cardiac Remodeling

ObjectivesThis study speculated that longitudinal strain curves in left bundle branch block (LBBB) could be shaped by the degree of LBBB-induced cardiac remodeling. BackgroundLBBB independently affects left ventricular (LV) structure and function, but large individual variability may exist in LBBB-induced adverse remodeling. MethodsConsecutive patients with LBBB with septal flash (LBBB-SF) underwent thorough echocardiographic assessment, including speckle tracking-based strain analysis. Four major septal longitudinal strain patterns (LBBB-1 through LBBB-4) were discerned and staged on the basis of: 1) correlation analysis with echocardiographic indexes of cardiac remodeling, including the extent of SF; 2) strain pattern analysis in cardiac resynchronization therapy (CRT) super-responders; and 3) strain pattern analysis in patients with acute procedural-induced LBBB. ResultsThe study enrolled 237 patients with LBBB-SF (mean age: 67 ± 13 years; 57% men). LBBB-1 was observed in 60 (26%), LBBB-2 in 118 (50%), LBBB-3 in 29 (12%), and LBBB-4 in 26 (11%) patients. Patients at higher LBBB stages had larger end-diastolic volumes, lower LV ejection fractions, longer QRS duration, increased mechanical dyssynchrony, and more prominent SF compared with less advanced stages (p < 0.001 for all). Among CRT super-responders (n = 30; mean age: 63 ± 10 years), an inverse transition from stages LBBB-3 and -4 (pre-implant) to stages LBBB-1 and -2 (pace-off, median follow-up of 66 months [interquartile range: 32 to 78 months]) was observed (p < 0.001). Patients with acute LBBB (n = 27; mean age: 83 ± 5.1 years) only presented with a stage LBBB-1 (72%) or -2 pattern (24%). ConclusionsThe proposed classification suggests a pathophysiological continuum of LBBB-induced LV remodeling and may be valuable to assess the attribution of LBBB to the extent of LV remodeling and dysfunction.

Consequences of power law scattering from soft tissues

A recent series of theoretical and experimental results support the hypothesis that ultrasound speckle statistics and backscatter are deeply rooted in power law behaviors. The implications for the tissue characterization are direct and lead to Burr distributions for speckle analysis and the H-scan analysis for the tissue characterization.

The effect of intraocular pressure elevation and related ocular biometry changes on corneal OCT speckle distribution in porcine eyes.

The aim of this study was to evaluate the influence of increase in intraocular pressure (IOP) and cooccurring changes in ocular biometry parameters on the corneal optical coherence tomography (OCT) speckle distribution in ex-vivo experiments on porcine intact eyes. Twenty-three eyeballs were used in the inflation test where IOP in the anterior chamber was precisely set from 10 mmHg to 40 mmHg in steps of 5 mmHg and where eye biometry was utilized (IOL Master 700). To assess the influence of the duration of the experiment on the OCT speckle statistics, the second experiment was performed with 10 eyeballs at the constant IOP of 15 mmHg. Based on the OCT scans of central cornea (Copernicus REVO), spatial maps of the scale parameter (a) and the shape parameter (v) of the gamma distribution speckle model were estimated. The means of both parameters for each spatial map were computed within the 2 mm of the central stroma. Both distributional parameters statistically significantly varied with IOP and time (one way repeated measures ANOVA, all p-values < 0.001). The a parameter revealed a faster statistically significant increase in IOP up to 25 mmHg, regardless of time. Central corneal thickness (CCT), the anterior chamber depth, and the mean equivalent spherical power varied significantly with IOP, whereas CCT and axial length changed statistically significantly with time. Statistically significant correlation was found between CCT and the a parameter, after removing IOP as a confounding factor (r = −0.576, p < 0.001). The parameters of the gamma distribution can be used not only for identifying IOP induced changes in the optical scattering within the corneal stroma, but also in corneal geometry. The approach of corneal speckle analysis could be potentially utilized for an indirect and noninvasive assessment of some properties of corneal stroma.

Remote Photoacoustic Sensing Using Single Speckle Analysis by an Ultra-Fast Four Quadrant Photo-Detector.

The need for tissue contact makes photoacoustic imaging not applicable for special medical applications like wound imaging, endoscopy, or laser surgery. An easy, stable, and contact-free sensing technique might thus help to broaden the applications of the medical imaging modality. In this work, it is demonstrated for the first time that remote photoacoustic sensing by speckle analysis can be performed in the MHz sampling range by tracking a single speckle using a four quadrant photo-detector. A single speckle, which is created by self-interference of surface back-reflection, is temporally analyzed using this photo-detector. Phantoms and skin samples are measured in transmission and reflection mode. The potential for miniaturization for endoscopic application is demonstrated by fiber bundle measurements. In addition, sensing parameters are discussed. Photoacoustic sensing in the MHz sampling range by single speckle analysis with the four quadrant detector is successfully demonstrated. Furthermore, the endoscopic applicability is proven, and the sensing parameters are convenient for photoacoustic sensing. It can be concluded that a single speckle contains all the relevant information for remote photoacoustic signal detection. Single speckle sensing is therefore an easy, robust, contact-free photoacoustic detection technique and holds the potential for economical, ultra-fast photoacoustic sensing. The new detection technique might thus help to broaden the field of photoacoustic imaging applications in the future.

Deep learning enhances polarization speckle for in vivo skin cancer detection

Polarization speckle is a growing research field, especially for the purposes of biomedical imaging and diagnostics. The statistical uniformity of speckle creates novel opportunities for AI methods to analyze speckle patterns, as they are difficult for a human to interpret. We employed deep learning and traditional machine learning methods (Support Vector Machine, K Nearest Neighbor, and Random Forests) to analyze polarization speckle images generated from the general categories of malignant and benign lesions, a classification task previously found to be very difficult. Their performance in classifying the patterns were compared both to each other and to the previous statistical methods of speckle analysis. A collection of 122 malignant and 196 benign skin lesion speckle images were augmented for deep learning using patch cropping, an advantageous method given the patterns’ statistical homogeneity. The machine learning technique performed with a diagnostic accuracy of less than 65%, a result comparable to those of previous statistical methods, despite the fact that the same machine learning technique could achieve a high 90% accuracy in the simpler classification task of differentiating malignant melanoma and the benign lookalike seborrheic keratosis. However, ResNet, our chosen deep learning architecture, achieved the best performance of 82% diagnostic accuracy in the general classification task of malignant and benign. These results show that deep learning extracts previously hidden information from polarization speckle, which further develops towards a rapid, real-time, analysis technique for an automatic skin cancer detection system.

Survival in acute heart failure in intensive cardiac care unit: a prospective study.

The aim of this study is to identify the best predictors of mortality among clinical, biochemical and advanced echocardiographic parameters in acute heart failure (AHF) patients admitted to coronary care unit (CCU). AHF is a clinical condition characterized by high mortality and morbidity. Several studies have investigated the potential prognostic factors that could help the risk assessment of cardiovascular events in HF patients, but at the moment it has not been found a complete prognostic score (including clinical, laboratory and echocardiographic parameters), univocally used for AHF patients. Patients (n = 118) admitted to CCU due to AHF de novo or to an exacerbation of chronic heart failure were enrolled. For each patient, clinical and biochemical parameters were reported as well as the echocardiographic data, including speckle tracking echocardiography analysis. These indexes were then related to intra- and extrahospital mortality. At the end of the follow-up period, the study population was divided into two groups, defined as 'survivors' and 'non-survivors'. From statistical analysis, C-reactive protein (CRP) (AUC = 0.75), haemoglobin (AUC = 0.71), creatinine clearance (AUC = 0.74), left atrial strain (AUC = 0.73) and freewall right ventricular strain (AUC = 0.76) showed the strongest association with shortterm mortality and they represented the items of the proposed risk score, whose cut-off of 3 points is able to discriminate patients at higher risk of mortality. AHF represents one of the major challenges in CCU. The use of a combined biochemical and advanced echocardiographic score, assessed at admission, could help to better predict mortality risk, in addition to commonly used indexes.

Dynamic laser speckle analysis using the event sensor

Dynamic laser speckle analysis (DLSA) can obtain useful information about the scene dynamics. Traditional implementations use intensity-based imaging sensors such as a complementary metal oxide semiconductor and charge-coupled device to capture time-varying intensity frames. We use an event sensor that measures pixel-wise asynchronous brightness changes to record speckle pattern sequences. Our approach takes advantage of the low latency and high contrast sensitivity of the event sensor to implement DLSA with high temporal resolution. We also propose two evaluation metrics designed especially for event data. Comparison experiments are conducted in identical conditions to demonstrate the feasibility of our proposed approach.

Detection of carious lesion by laser speckle analysis using the first order moment

Carious lesion is one of the most prevalent diseases in humankind, affecting nearly all human beings at least once in a lifetime. Early carious lesion (ECL, also known as white spot lesion) is part of the caries process in which the enamel surface loses mineral but the subsurface layer overlying the mineral-poor region remains intact. In its early stages, the detection of the carious lesion is currently still a major challenge because it is based on visual inspection, thus with an inherent subjectivity. In this work, we present a method to detect and assess the severity of ECLs using a computer-assisted laser speckle imaging technique. Forty-five polished and cut bovine incisors samples allow a paired t-test by exposing half of the surface while protecting the other half. The samples, included in a PVC tube, were immersed in 50ml of a solution (pH 5.0) containing 0.05M acetate buffer solution and 50% saturated hydroxyapatite enamel powder at 37°C. The etching time is 24h; 48h and 72h; each group contain 15 samples. We illuminate each sample with a laser and analyse the first momentum of the laser speckle images with a computer. Our results shows that the first momentum of the LSI of the sound region statistically differs from the decay region of the samples for all groups (p&lt;0.0001). We also found a strong correlation between the acid etch duration (severity of the decay) and the shift in LSI contrast (Pearson’s correlation coefficient ρ=0.9989, R²=0.9978). Detecting decay in its early stages is still a challenge in the clinical practice, however this work demonstrates that the analysis of the statistical features of the laser speckle image in the spatial domain allows for the detection of microstructural changes in the enamel associated with the presence of the lesion even before any intervention is required.

Quantization of dynamic speckle patterns with spatially varying statistics.

Raw data compression is mandatory for monitoring of processes by dynamic speckle analysis when two-dimensional activity maps are built by pointwise statistical processing of correlated speckle patterns formed on the surface of diffusely reflecting objects under laser illumination. Coarse quantization of speckle patterns enables storage and transfer of a huge amount of images, but it may be inefficient at spatially varying speckle statistics, such as for patterns recorded at non-uniform illumination or reflectivity. We prove efficacy of coarse quantization of the raw speckle data with varying statistics for a normalized algorithm by simulation and a polymer drop drying experiment. Both uniform and non-uniform quantization are proposed for treating such data. Decreasing the bit depth from 8 to 3 is possible without worsening the quality of the activity map.

Decreased layer specific longitudinal strain in myocardial segments supplied by stenosed LAD coronary artery: analysis for baseline, peak and recovery phase of stress echocardiography

Abstract Background Despite wide utility of global longitudinal strain in the assessment of left ventricular function up to now little is known about layer specific quantification of myocardial function during stress tests and its potential for ischemia detection. Purpose To investigate diagnostic utility of layer specific LS during stress echocardiography using marker segments in patients with established Left Anterior Descending (LAD) coronary artery status. Methods We retrospectively analyzed 63 patients (mean age 62.5±9.9 years, 62% males) with suspected coronary artery disease, who had performed dobutamine stress echocardiography (DSE). Layer specific speckle tracking LS analyses were performed during rest, maximal stress and recovery. As a marker for LAD (segment most probably supplied by this artery) we used mid-anterior left ventricle segments. LAD status were established with coronary angiography or angioCT and consider as significant if ≥70% stenosis was present. Results In our study group 14 patients had significantly stenosed LAD (group 1) and 24 had normal coronaries (group 2). We detected significantly lowered absolute values of strain in endocardial and mid-myocardial layers of segments supplied by stenosed LAD at rest for endocardium −8.6% (group 1) vs −13.4% (group 2); p=0.045; and mid-myocardium −7.3% (group 1) vs −11.2% (group 2); p=0.044. Moreover, we observed similar trend at recovery, however without reaching statistical significance. Conclusions Longitudinal strain analysis focused on segments supplied by assessed coronary artery my provide quantitative data confirming ischemia in the settings of rest and stress echocardiography. Our pilot study suggest that for inotropic agents like dobutamine the potential ischemic dysfunction may be however masked at peak stage of the test. Funding Acknowledgement Type of funding source: None

P.174 Variation in OXTR gene is associated with current depression severity and possibly mediates the effects of recent negative life events

Hepatorenal syndrome (HRS) is a life-threatening complication of end-stage liver disease characterized by the rapid decline of kidney function. Herein, we explored the therapeutic potential of targeting the cannabinoid-2 receptor (CB2-R) utilizing a commonly used mouse model of liver fibrosis and hepatorenal syndrome (HRS), induced by bile duct ligation (BDL).Gene expression analysis, histological evaluation, determination of serum levels of renal injury-biomarkers were used to characterize the BDL-induced organ injury; laser speckle analysis to measure microcirculation in the kidneys.We found that liver injury triggered marked inflammation and oxidative stress in the kidneys of BDL-operated mice. We detected pronounced histopathological alterations with tubular injury paralleled with increased inflammation, oxidative/nitrative stress and fibrotic remodeling both in hepatic and renal tissues as well as endothelial activation and markedly impaired renal microcirculation. This was accompanied by increased CB2-R expression in both the liver and the kidney tissues of diseased animals. A selective CB2-R agonist, HU-910, markedly decreased numerous markers of inflammation, oxidative stress and fibrosis both in the liver and in the kidneys. HU-910 also attenuated markers of kidney injury and improved the impaired renal microcirculation in BDL-operated mice.Our results suggest that oxidative stress, inflammation and microvascular dysfunction are key events in the pathogenesis of BDL-associated renal failure. Furthermore, we demonstrate that targeting the CB2-R by selective agonists may represent a promising new avenue to treat HRS by attenuating tissue and vascular inflammation, oxidative stress, fibrosis and consequent microcirculatory dysfunction in the kidneys.

P.172 No association between OXTR1, lifetime depression and childhood trauma in a European general population sample

Hepatorenal syndrome (HRS) is a life-threatening complication of end-stage liver disease characterized by the rapid decline of kidney function. Herein, we explored the therapeutic potential of targeting the cannabinoid-2 receptor (CB2-R) utilizing a commonly used mouse model of liver fibrosis and hepatorenal syndrome (HRS), induced by bile duct ligation (BDL).Gene expression analysis, histological evaluation, determination of serum levels of renal injury-biomarkers were used to characterize the BDL-induced organ injury; laser speckle analysis to measure microcirculation in the kidneys.We found that liver injury triggered marked inflammation and oxidative stress in the kidneys of BDL-operated mice. We detected pronounced histopathological alterations with tubular injury paralleled with increased inflammation, oxidative/nitrative stress and fibrotic remodeling both in hepatic and renal tissues as well as endothelial activation and markedly impaired renal microcirculation. This was accompanied by increased CB2-R expression in both the liver and the kidney tissues of diseased animals. A selective CB2-R agonist, HU-910, markedly decreased numerous markers of inflammation, oxidative stress and fibrosis both in the liver and in the kidneys. HU-910 also attenuated markers of kidney injury and improved the impaired renal microcirculation in BDL-operated mice.Our results suggest that oxidative stress, inflammation and microvascular dysfunction are key events in the pathogenesis of BDL-associated renal failure. Furthermore, we demonstrate that targeting the CB2-R by selective agonists may represent a promising new avenue to treat HRS by attenuating tissue and vascular inflammation, oxidative stress, fibrosis and consequent microcirculatory dysfunction in the kidneys.

P.093 Significant associations between oxytocin receptor gene and anxiety symptoms in interaction with recent negative life events

Hepatorenal syndrome (HRS) is a life-threatening complication of end-stage liver disease characterized by the rapid decline of kidney function. Herein, we explored the therapeutic potential of targeting the cannabinoid-2 receptor (CB2-R) utilizing a commonly used mouse model of liver fibrosis and hepatorenal syndrome (HRS), induced by bile duct ligation (BDL).Gene expression analysis, histological evaluation, determination of serum levels of renal injury-biomarkers were used to characterize the BDL-induced organ injury; laser speckle analysis to measure microcirculation in the kidneys.We found that liver injury triggered marked inflammation and oxidative stress in the kidneys of BDL-operated mice. We detected pronounced histopathological alterations with tubular injury paralleled with increased inflammation, oxidative/nitrative stress and fibrotic remodeling both in hepatic and renal tissues as well as endothelial activation and markedly impaired renal microcirculation. This was accompanied by increased CB2-R expression in both the liver and the kidney tissues of diseased animals. A selective CB2-R agonist, HU-910, markedly decreased numerous markers of inflammation, oxidative stress and fibrosis both in the liver and in the kidneys. HU-910 also attenuated markers of kidney injury and improved the impaired renal microcirculation in BDL-operated mice.Our results suggest that oxidative stress, inflammation and microvascular dysfunction are key events in the pathogenesis of BDL-associated renal failure. Furthermore, we demonstrate that targeting the CB2-R by selective agonists may represent a promising new avenue to treat HRS by attenuating tissue and vascular inflammation, oxidative stress, fibrosis and consequent microcirculatory dysfunction in the kidneys.

Non-invasive in situ monitoring of bone scaffold activity by speckle pattern analysis.

Scaffold-based bone tissue engineering aims to develop 3D scaffolds that mimic the extracellular matrix to regenerate bone defects and damages. In this paper, we provide a laser speckle analysis to characterize the highly porous scaffold. The experimental procedure includes in situ acquisition of speckle patterns of the bone scaffold at different times under preserved environmental conditions, and follow-up statistical post-processing toward examining its internal activity. The activity and overall viscoelastic properties of scaffolds are expressed via several statistical parameters, and the variations in the computed parameters are attributed to time-varying activity of the samples during their internal substructure migration.

Biological activity using dynamic speckle in blood serum of mares in different reproductive stages

This study aimed to evaluate the biological activity in blood serum plasma samples from mares at different reproductive stages using dynamic speckle analysis. For this purpose, samples were collected from 40 Mangalarga Machador mares from the Formoso 2S horse farm in Cajueiro, AL. The mares were classified into four groups of ten animals each according to the pregnancy stage: ten empty mares (not pregnant), ten pregnant mares in the early third of pregnancy between one month and four months, ten pregnant mares in the final third of the pregnancy between seven and eleven months, and ten lactating mares (within two months post-partum). The biological activity response using a dynamic speckle (biospeckle) was obtained by capturing images reflected by a coherent light (diode laser with a wavelength of 532 nm and intensity of 3 mW) on a sample using a CCD (charge coupled device) camera. This data was analyzed using image processing techniques through the computational application Speckle-THSP-MCO-Descritores (STMD), applying THSP (time history speckle pattern) methodology, which evaluates the temporal evolution of the interference image from spreading over the sample surface over time. A coherence matrix generated from the THSP was used to present the intensity module dispersion, which provided the bioactivity data. These data were then processed using the program OriginPro 8. Ink, generate graphs and compare the results from the different groups under study. A general biospeckle signature was observed regardless of the mares’ reproductive stage considered in this study. A short phase of movement of the samples associated with an accommodation of the drop on the slide was observed. It was followed by an ascending curve starting between 5 and 10 min of observation, reaching a peak within 15 and 25 min, and finally decayed uniformly until almost zero after 45 min. The group of pregnant mares in the final third of pregnancy presented superior bioactivity compared to pregnant mares in the early third of pregnancy. The curve observed for the group of lactating mares is similar to the curve obtained for the group of pregnant mares in the early third of pregnancy. Bioactive molecules act as dispersion elements of coherent light incident on a sample. The variation inherent to the presence of bioactive molecules in the different stages evaluated influenced the biospeckle pattern detected in each sample. It was concluded that the biological activity peaks of the blood plasma samples from the mares evaluated in this study using the dynamic speckle analysis technique were different for both amplitude and time of occurrence, according to the different reproductive stages.

The Use of Speckle Correlation Analysis to Determine Blood Flow Velocity

Currently, optical methods based on the registration of speckle dynamics are widely used in modern diagnostics of the microvasculature. The results of the development of a laboratory model of a small-sized non-contact speckle sensor of the microvasculature and the experimental procedure are presented. A speckle sensor model for determining the blood flow velocity in the microvasculature is given, on the basis of which a prototype sensor can be created. The results of preliminary experimental studies of the possibility of blood microcirculation monitoring in the microvasculature using speckle correlation analysis are presented. A group of conditionally healthy volunteers aged 18 to 24 years was analyzed during the experiments. The obtained results correlate with the results presented in the literature on the value of the determined blood flow velocity. Problems and prospects of speckle correlation monitoring of the microvasculature in laboratory and clinical conditions are discussed.

Laser Speckle Analysis of Water Stress in Plant Leaf

Laser Speckle Analysis of Water Stress in Plant Leaf

Base friction test on unloading deformation mechanism of soft foundation waste dump under gravity

Abstract Problems of waste dumps induced by foundation weaken are quite common. A series of base friction tests were conducted in order to reveal the unloading deformation mechanism of soft foundation waste dumps. The displacement histories of waste dumps were measured by a speckle analysis and displacement measurement system and compared with hard foundation waste dumps. The test results showed that: (1) the stability of a soft foundation waste dump is obviously worse than that of a hard foundation waste dump. (2) The deformation and failure mode of a hard foundation waste dump shows a collapse-traction-push feature, and it starts from the low-grade slope and develops towards the high-grade slope. (3) The deformation and failure mode of a soft foundation waste dump is mainly controlled by the soft foundation. The non-uniform unloading settlement between front and rear parts of the waste dump results in the cyclic subsidence-crack-slip, until all the slopes above the soft foundation slide. (4) Cracks in a soft foundation waste dump first initiate at the slope bottom and propagate upwards until penetrate the whole slope, but the generation and extension pattern of cracks is opposite in a hard foundation waste dump. Cracks in a soft foundation waste dump are dislocation cracks; however, cracks in a hard foundation waste dump are tension cracks. (5) The reinforcement measures such as dynamic consolidation and borehole grouting are recommended for a soft foundation waste dump, and a drainage system could be constructed to discharge water from the dump site. These results can provide reference for further research of unloading deformation of soft foundation waste dumps under gravity.

Experimental study of speckle patterns generated by low-coherence semiconductor laser light.

Speckle is a wave interference phenomenon that has been studied in various fields, including optics, hydrodynamics, and acoustics. Speckle patterns contain spectral information of the interfering waves and of the scattering medium that generates the pattern. Here, we study experimentally the speckle patterns generated by the light emitted by two types of semiconductor lasers: conventional laser diodes, where we induce low-coherence emission by optical feedback or by pump current modulation, and coupled nanolasers. In both cases, we analyze the intensity statistics of the respective speckle patterns to inspect the degree of coherence of the light. We show that the speckle analysis provides a non-spectral way to assess the coherence of semiconductor laser light.

Blood Flow Visualization by Means of Laser Speckle-Contrast Measurements under the Conditions of Nonergodicity

The influence of stationary structural inclusions in inhomogeneous strongly scattering media such as biotissues on the results of speckle-contrast measurements using temporal and spatial methods of image processing by means of laser speckle-contrast imaging is investigated. The limits of applicability of the method of laser speckle-contrast imaging are established in detail for the case in which ergodicity conditions are not fulfilled. Based on model experiments, it is demonstrated that an increase in the number of stationary scatterers relative to that of the dynamic ones in the sampling volume introduces substantial error into the results of spatial and temporal processing of speckle images for given exposure time of the detector. At the same time, analysis of spatial and temporal speckle contrasts, the values of the coefficient of speckle dynamics, along with the results of Monte-Carlo simulation of the sampling volume, revealed that the presence of a relatively thin, up to 30% of entire volume, static layer does not introduce considerable changes into the results of measurements by the method of laser speckle-contrast imaging. The exposure time of the camera, along with the number of frames used for image processing, can be varied and chosen individually for each experiment. The developed algorithms of spatial and temporal processing of images obtained by the method of laser speckle-contrast imaging were tested in the experiments on transcranial visualization of the cerebral blood flow of a mouse.