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[IEEE 2019 41st Annual International Conference of the IEEE Engineering in Medicine & Biology Society (EMBC) - Berlin, Germany (2019.7.23-2019.7.27)] 2019 41st Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) - Hyperspectral imaging for thermal effect monitoring in in vivo liver during laser ablation
摘要： Thermal ablation is a minimally invasive technique used to induce a controlled necrosis of malignant cells by increasing the temperature in localized areas. This procedure needs an accurate and real-time monitoring of thermal effects to evaluate and control treatment outcome. In this work, a hyperspectral imaging (HSI) technique is proposed as a new and non-invasive method to monitor ablative therapy. HSI provides images of the target object in several spectral bands, hence the reflectance/absorbance spectrum for each pixel. This paper presents a preliminary and original HSI-based analysis of the thermal state in the in vivo porcine liver undergoing laser ablation. In order to compare the spectral response between treated and untreated areas of the organ, proper Regions of Interest (ROIs) were chosen on the hyperspectral images; for each ROI, the absorbance variation for the selected wavelengths (i.e., 630, 760, and 960nm, for deoxyhemoglobin, methemoglobin, and water respectively) was assessed. Results obtained during and after laser ablation show that the absorbance of the methemoglobin peaks increases up to 40% in the burned region with respect to the non-ablated one. Conversely, the relative change of deoxyhemoglobin and water peaks is less marked. Based on these results, absorbance threshold values were retrieved and used to visualize the ablation zone on the images. This preliminary analysis suggests that a combination of the absorbance information is essential to achieve a more accurate identification of the ablation region. The results encourage further studies on the correlation between thermal effects and the spectral response of biological tissues undergoing thermal ablation, for final clinical use.
关键词： laser ablation,absorbance spectrum,in vivo porcine liver,hyperspectral imaging,thermal ablation
更新于2025-09-16 10:30:52
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Imagerie par laser speckle d’une malformation artério-veineuse chez un nourrisson
摘要： Nous présentons une nouvelle technique de vidéo-dermoscopie appelée microscopie à fluorescence (MaF) et ses premières applications en dermatologie. Le système optique-électronique est équipé d’une sonde éclairée par une lumière monochromatique de longueur d’onde (λ) de 405 nm (± 5 nm) et un angle fixe d’émission. Le principe de fonctionnement est basé sur la capacité des chromophores endogènes d’absorber des λ spécifiques. La composante optique a un grossissement de 12 fois, une mise au point manuelle sur couches successives, chacune de profondeur de 35/50 μm ; avec une profondeur maximale variable de 200 à 400 μm. Le champ de vision est de 340 μm. Le capteur d’image a une sensibilité (> 50 % pour λ = 400—810 nm) et une cadence (1 frame rate/8,33 ms) élevées. Ces caractéristiques permettent la visualisation des structures de la peau jusqu’au derme papillaire avec un grossissement de 500×. Les papilles se présentent comme des structures rondes ou elliptiques brillantes, régulières, où on peut identifier une seule couche de cellules sombres disposées en circonférence autour de chaque papille. La MaF est particulièrement utile dans la visualisation des structures vasculaires superficielles. Nous avons également démontré un intérêt dans des cas d’affection parasitaires et mycosiques.
关键词： Vidéodermoscopie,Observation in vivo,Microscopie à fluorescence
更新于2025-09-16 10:30:52
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Minimally invasive laser Doppler flowmetry is suitable for serial bone perfusion measurements in mice
摘要： In vivo laser Doppler flowmetry (LDF) has previously been used to quantify blood perfusion accurately at a single timepoint in the murine tibial metaphysis. However, this procedure entailed substantial disruption to soft tissues overlying the bone and caused notable localized inflammation for several weeks after the procedure, impeding serial measurements in the same mouse. In this study, we tested a less invasive technique to measure perfusion in the tibia with LDF and determined that it can be used serially in the same mouse without causing signs of inflammation or gait perturbations. Twenty 14-week-old C57Bl/6J mice were evenly divided into groups that either had daily treadmill exercise or remained sedentary. Within these activity groups, mice were evenly subdivided into groups that received LDF measurements either weekly or only once at the study endpoint. Bone perfusion was measured with LDF in the anteromedial region of the right tibial metaphysis. Serum concentrations of interleukin 6, incision site wound area, and interlimb coordination during gait were measured weekly for four weeks. Tibial perfusion did not differ significantly between exercise and sedentary groups within the weekly or endpoint-only LDF groups at any timepoint. Perfusion was significantly increased in the third week in the weekly LDF group relative to measurements in the second and fourth weeks. Ligation of the femoral artery caused consistent, rapid reductions in tibial perfusion, validating that LDF is sensitive to changes in tibial blood supply. Weekly LDF procedures did not adversely affect gait, as interlimb coordination during treadmill locomotion was similar between weekly and endpoint-only LDF groups at every timepoint. Images of the incision site show wound closure within one week, and serum concentrations of interleukin 6 were not significantly different between weekly and endpoint-only groups. Together, these findings demonstrate that our minimally invasive LDF technique is suitable for serial in vivo measurements of intraosseous blood perfusion without inducing localized inflammation or negatively affecting gait patterns in mice.
关键词： Laser Doppler flowmetry,Vascular supply,Serial measurement,In vivo,Bone blood perfusion,Minimally invasive
更新于2025-09-16 10:30:52
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Evaluation of digital staining for ex vivo confocal laser scanning microscopy
摘要： Background: Ex vivo confocal laser scanning microscopy (CLSM) is a novel diagnostic tool for the fast examination of native tissue. However, CLSM produces black/white/green images, depending on the refraction indices of the tissue structures, complemented by nuclear fluorescence staining, which the vast majority of Mohs surgeons and dermatopathologists are not trained to interpret. Digital staining is applicable to ex vivo CLSM investigations to simulate the images of conventional slides stained with haematoxylin & eosin (H&E). Objectives: The aim of our study was to evaluate in detail the appearance of human skin structures using digitally stained ex vivo CLSM images and compare the results to that of conventional H&E slides of the same specimen. Methods: After providing informed consent, 26 patients donated their Burow’s triangles (healthy skin) that resulted from plastic reconstruction after the R0- excision of skin tumours. After being investigated by ex vivo CLSM, including automated digital staining (VivaScope 2500M-4G, MAVIG GmbH), the specimens were fixed in formalin, embedded in paraffin and stained with H&E. Results: Almost all skin structures in the digitally stained ex vivo CLSM images morphologically resembled the structures in the histopathological images acquired from H&E slides. Due to the high refraction index of melanin, the hair shafts appeared bright pink, and the melanocytes and melanophages were poorly imaged, resulting in a strong pink appearance that vastly differed from the appearance of conventional H&E-stained histopathology. Conclusions: Digital staining of ex vivo CLSM images is an easy and highly useful tool to facilitate the interpretation of black-field images generated by confocal laser scanning microscopy for dermatopathologists and Mohs surgeons who are familiar with H&E staining. Unlike the pigmented structures, the cutaneous and subcutaneous structures had excellent visualization with only minimal differences from their appearance on H&E slides.
关键词： digital staining,ex vivo confocal laser scan microscopy,dermatopathology
更新于2025-09-16 10:30:52
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Photoacoustic Imaging Quantifies Drug Release from Nanocarriers via Redox Chemistry of Dye‐Labeled Cargo
摘要： There have been remarkable advances in imaging drug nanocarriers, but there are few real-time imaging strategies to determine if the cargo has been released from the carrier. This is important because the pharmacokinetics and pharmacodynamics of the carrier can often be dramatically decoupled from that of the cargo. Thus, new tools are clearly needed to image the timing and quantity of drug release from nanocarriers. Here, we describe a simple strategy for photoacoustic monitoring of drug release based on the redox chemistry of methylene blue, which offers predictable redox chemistry: It can transition from the oxidized state with a bright blue color and robust photoacoustic signal to the reduced state that the transparent with no photoacoustic signal. We locked this drug-dye conjugate into a reduced state inside of a nanoparticle with no photoacoustic signal. As the drug is released from the carrier, the dye is oxidized for quantification with photoacoustic imaging. We first prepared paclitaxel-methylene blue conjugate (PTX-MB) with strong absorbance at 640 nm and photoacoustic intensity proportional to its concentration. This cargo was co-encapsulated in a poly(lactic-co-glycolic acid) nanoparticle with a dithiothreitol reducing agent. The IC50 of PTX-MB-loaded NPs (PTX-MB @ PLGA NPs) was 78 μg mL-1. We then used the redox reaction of PTX-MB to monitor its release from poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs). In vitro drug-release in phosphate buffer saline with 20% v/v normal mice serum showed a 670-fold increase in photoacoustic signal. The particles showed an initial burst release (25%) during the first 24 hours. After 24 hours, a sustained release was observed through 120 hours leading to cumulative release of 40.6% of PTX-MB. In vivo drug release study in mice for a duration of 12 hours showed a photoacoustic signal enhancement of up to 649% after 10 hours. We then used this system to treat an orthotopic model of colon cancer via luciferase-positive CT26 cells. Our data showed that tumor burden decreased by 44.7% ± 4.8% when treated with the PTX-MB @ PLGA NPs versus the empty PLGA carrier. This work presents a direct strategy to simultaneously monitor drug release biodistribution.
关键词： Photoacoustic imaging,Paclitaxel,Image-guided drug delivery,PLGA nanoparticles,Drug-release,Cancer therapy,in vivo monitoring
更新于2025-09-16 10:30:52
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Monitoring the dynamics of acute radiofrequency ablation lesion formation in thin-walled atria – a simultaneous optical and electrical mapping study
摘要： Background: Radiofrequency ablation (RFA) is a common approach to treat cardiac arrhythmias. During this intervention, numerous strategies are applied to indirectly estimate lesion formation. However, the assessment of the spatial extent of these acute injuries needs to be improved in order to create well-defined and durable ablation lesions. Methods: We investigated the electrophysiological characteristics of rat atrial myocardium during an ex vivo RFA procedure with fluorescence-optical and electrical mapping. By analyzing optical data, the temporal growth of punctiform ablation lesions was reconstructed after stepwise RFA sequences. Unipolar electrograms (EGMs) were simultaneously recorded by a multielectrode array (MEA) before and after each RFA sequence. Based on the optical results, we searched for electrical features to delineate these lesions from healthy myocardium. Results: Several unipolar EGM parameters were monotonically decreasing when distances between the electrode and lesion boundary were smaller than 2 mm. The negative component of the unipolar EGM [negative peak amplitude (Aneg)] vanished for distances lesser than 0.4 mm to the lesion boundary. Median peak-to-peak amplitude (Vpp) was decreased by 75% compared to baseline. Conclusion: Aneg and Vpp are excellent parameters to discriminate the growing lesion area from healthy myocardium. The experimental setup opens new opportunities to investigate EGM characteristics of more complex ablation lesions.
关键词： acute ablation lesions,ex vivo RFA procedure,electrical mapping,unipolar electrograms,fluorescence-optical mapping
更新于2025-09-16 10:30:52
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Bidirectional in vivo structural dendritic spine plasticity revealed by two-photon glutamate uncaging in the mouse neocortex
摘要： Most excitatory synapses in the brain form on dendritic spines. two-photon uncaging of glutamate is widely utilized to characterize the structural plasticity of dendritic spines in brain slice preparations in vitro. In the present study, glutamate uncaging was used to investigate spine plasticity, for the first time, in vivo. A caged glutamate compound was applied to the surface of the mouse visual cortex in vivo, revealing the successful induction of spine enlargement by repetitive two-photon uncaging in a magnesium free solution. Notably, this induction occurred in a smaller fraction of spines in the neocortex in vivo (22%) than in hippocampal slices (95%). Once induced, the time course and mean long-term enlargement amplitudes were similar to those found in hippocampal slices. However, low-frequency (1–2 Hz) glutamate uncaging in the presence of magnesium caused spine shrinkage in a similar fraction (35%) of spines as in hippocampal slices, though spread to neighboring spines occurred less frequently than it did in hippocampal slices. Thus, the structural plasticity may occur similarly in the neocortex in vivo as in hippocampal slices, although it happened less frequently in our experimental conditions.
关键词： neocortex,in vivo,dendritic spines,glutamate uncaging,structural plasticity
更新于2025-09-16 10:30:52
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[IEEE 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Huangshan, China (2019.8.5-2019.8.8)] 2019 18th International Conference on Optical Communications and Networks (ICOCN) - In vivo and online temperature monitoring based on fiber Bragg greatings during tumor treatment with nanosecond pulse electric field
摘要： the clinical practice, a compact, in-vivo and online monitoring scheme is an important requirement. A fiber Bragg grating (FBG) sensing system was used to online monitor the temperature at the surface of / inside the liver tissue of a rabbit under nanosecond pulse electric field (nsPEF). Single point measurement between the electrodes and multi-point measurement surrounding one electrode were both carried out. Experimental results show that, due to equally spaced (Δt=0.5 s) 300 ns-pulses with E=20 kV/cm at a repetition rate of 4 Hz, the temperature rise in the rabbit liver tumor usually does not exceed ΔΤ=6℃ for 300 pulses. Theoretical analysis of Joule heating model fits well with the experimental results. Both direct measurements and theoretical modelling demonstrated that nsPEF could not deliver enough energy to heat the treated tissue significantly, thus a hyperthermic effect on the tissue can be excluded during this kind of treatment with much high electric field strength and extremely short duration.
关键词： Fiber Bragg grating,Nanosecond pulse electric field,In-vivo temperature monitoring
更新于2025-09-16 10:30:52
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In Vivo Experimental Study on the Enhancement of Optical Clearing Effect by Laser Irradiation in Conjunction with a Chemical Penetration Enhancer
摘要： The penetration of optical clearing agents (OCAs) is restricted by the natural barrier function of the stratum corneum (SC) of the skin, which can be breached by physical and chemical methods to enhance the transcutaneous delivery of OCAs. To breach the barrier function of SC, we carried out the in vivo experimental study to enhance the optical clearing effect of PEG-400 by laser irradiation in conjunction with a chemical penetration enhancer thiazone. We compared the re?ectance spectra of skin without laser irradiation or thiazone. Mono-treatment of thiazone could not signi?cantly enhance the optical clearing ef?cacy of the skin. After 60 min, the re?ectance spectrum decreased by only approximately 10%. With the combined treatment, the re?ectance spectrum decreased by approximately 30% after 10 min. Subsequently, the effect of laser dose on the enhancement of optical clearing ef?cacy was studied. The optimal irradiation dose was determined. The re?ectance of skins irradiated by a laser dose at 0.7 J/cm2 decreased by approximately 10% and were 20% lower than those at 0.5 and 0.9 J/cm2. The laser at 0.5 J/cm2 could not damage the SC completely, whereas the laser at 0.9 J/cm2 in?uenced the epidermis and dermis; thus, the re?ectance of skin samples irradiated by 0.9 J/cm2 did not decrease.
关键词： laser irradiation,tissue optical clearing technique,in vivo skin,optical clearing,thiazone,combined penetration enhancement
更新于2025-09-16 10:30:52
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In Vivo Fluorescence Visualization of Anterior Chamber Injected Human Corneal Endothelial Cells Labeled With Quantum Dots
摘要： The injection of cultured human corneal endothelial cells (cHCECs) into the anterior chamber (AC) is a newly developed modality for the successful treatment of corneal endothelium dysfunction. Here, we investigated whether or not cHCECs could be labeled using quantum dots (QDs) composed of semiconductor nanoparticle octa-arginine (R8) to trace injected cHCECs and examined the utility of in vivo fluorescence imaging to analyze the dynamics and accumulation of QD-labeled injected cHCECs in a corneal endothelial dysfunction mouse model.
关键词： cultured human corneal endothelial cells (cHCECs),in vivo fluorescence imaging,quantum dots (QDs)
更新于2025-09-16 10:30:52