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[IEEE 2018 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) - Honolulu, HI, USA (2018.7.18-2018.7.21)] 2018 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) - Tracing Tubular Structures from Teravoxel-Sized Microscope Images
摘要： Tracing vasculature and neurites from teravoxel-sized light-microscopy data-sets is a challenge impeding the availability of processed data to the research community. This is because (1) Holding terabytes of data during run-time is not easy for a regular PC. (2) Processing all the data at once would be slow and inefficient. In this paper, we propose a way to mitigate this challenge by Divide Conquer and Combine (DCC) method. We first split the volume into many smaller and manageable sub-volumes before tracing. These sub-volumes can then be traced individually in parallel (or otherwise). We propose an algorithm to stitch together the traced data from these sub-volumes. This algorithm is robust and handles challenging scenarios like (1) sub-optimal tracing at edges (2) densely packed structures and (3) different depths of trace termination. We validate our results using whole mouse brain vasculature data-set obtained from the Knife-Edge Scanning Microscopy (KESM) based automated tissue scanner.
关键词： Divide Conquer and Combine,Tracing,Neurites,Knife-Edge Scanning Microscopy,Teravoxel-sized,Microscope Images,Vasculature
更新于2025-09-23 15:21:01
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Quality improvement of acoustic-resolution photoacoustic imaging of skin vasculature based on practical synthetic-aperture focusing and bandpass filtering
摘要： We previously developed a compact acoustic-resolution photoacoustic (PA) imaging system with optical ?ber-based illumination, by which blood vessels in the rat skin were visualized in vivo. However, there were issues to be improved in the imaging characteristics: blurring in the out-of-focus region of the ultrasound sensor and degraded resolution due to low-frequency components in the PA signals. These are common limitations in acoustic-resolution PA imaging methods. In this study, we attempted to solve these problems by introducing signal processing methods based both on the synthetic-aperture focusing technique, which was applied only to signals in the detection zone of the sensor in the horizontal direction that was determined in advance in a phantom study, and on digital acoustic signal ?ltering with three speci?c frequency bands. Ex vivo and in vivo PA imaging of blood vessels in the rat skin and subcutaneous tissue showed the validity of the present signal processing methods.
关键词： photoacoustic imaging,bandpass ?ltering,skin vasculature,synthetic-aperture focusing
更新于2025-09-23 15:21:01
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<i>Frizzled 4</i> regulates ventral blood vessel remodeling in the zebrafish retina
摘要： Background: Familial exudative vitreoretinopathy (FEVR) is a rare congenital disorder characterized by a lack of blood vessel growth to the periphery of the retina with secondary fibrovascular proliferation at the vascular-avascular junction. These structurally abnormal vessels cause leakage and hemorrhage, while the fibroproliferative scarring results in retinal dragging, detachment and blindness. Mutations in the FZD4 gene represent one of the most common causes of FEVR. Methods: A loss of function mutation resulting from a 10-nucleotide insertion into exon 1 of the zebrafish fzd4 gene was generated using transcription activator-like effector nucleases (TALENs). Structural and functional integrity of the retinal vasculature was examined by fluorescent microscopy and optokinetic responses. Results: Zebrafish retinal vasculature is asymmetrically distributed along the dorsoventral axis, with active vascular remodeling on the ventral surface of the retina throughout development. fzd4 mutants exhibit disorganized ventral retinal vasculature with discernable tubular fusion by week 8 of development. Furthermore, fzd4 mutants have impaired optokinetic responses requiring increased illumination. Conclusion: We have generated a visually impaired zebrafish FEVR model exhibiting abnormal retinal vasculature. These fish provide a tractable system for studying vascular biology in retinovascular disorders, and demonstrate the feasibility of using zebrafish for evaluating future FEVR genes identified in humans.
关键词： retinal vasculature,FEVR,pericytes,optokinetic response
更新于2025-09-19 17:13:59
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[IEEE TENCON 2019 - 2019 IEEE Region 10 Conference (TENCON) - Kochi, India (2019.10.17-2019.10.20)] TENCON 2019 - 2019 IEEE Region 10 Conference (TENCON) - Point-of-care functional and molecular imaging using LED-based photoacoustics
摘要： Photoacoustic (PA) or optoacoustic imaging can visualize tissue-optical absorbers, especially hemoglobin, with optical contrast and ultrasound (US)-like resolution and imaging depth. Since both PA and US imaging involves US detection, it is straightforward to develop dual-mode imaging systems with unprecedented functional and structural imaging capabilities. Researchers have already demonstrated the potential of utilizing this complementary contrast imaging for several animal imaging experiments and early clinical pilot studies. PA conventionally uses slow, bulky and high-priced lasers as excitation sources. Use of these high-power pulsed lasers is hindering the clinical translation process of this imaging modality with tremendous potential. Advances in solid-state device technology have recently resulted in the development of a new class of high-power light emitting diodes (LEDs) that can be used as fast, robust and affordable pulsed excitation sources for PA imaging. In this paper, we review multiple LED-based PA/US imaging implementations (commercial and lab-made systems) and demonstrate its functional, molecular and structural imaging capabilities using several clinical/preclinical imaging examples. Specific focus will be given to 2D and 3D superficial vasculature and oxygen saturation imaging in multiple in vivo clinical and preclinical studies.
关键词： ultrasonography,vasculature,photoacoustic imaging,oxygenation imaging,LED
更新于2025-09-16 10:30:52
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Noncontact photoacoustic angiography with an air-coupled ultrasonic transducer for evaluation of burn injury
摘要： In vivo identi?cation of viable and thermally coagulated blood in a burn wound can be used to pro?le the type, extent, and site of the burn, thus assisting the removal of necrotic tissue in preparation for skin grafts. Recently, intensive research on photoacoustic imaging (PAI) has been conducted to evaluate burn injury. However, most PAI systems usually take the approach of direct physical contact of an acoustic detector or an impedance matching medium with the vulnerable burned skin, which exposes signi?cant limitations on the diagnosis of burn injuries. Here, we present a noncontact PAI system, based on a custom designed air-coupled ultrasonic transducer, enabling in vivo noncontact vasculature to be imaged without contrast agents. Using the natural difference in light absorption between coagulated and non-coagulated blood at the wavelength of 532 nm, this PAI system possesses an immanent advantage to discriminate viable and thermally coagulated blood in burned tissues. Phantom experiments and burned rabbit’s skin imaging have been implemented to demonstrate that the noncontact PAI technique could be valuable in the adjuvant diagnosis and observation of burns.
关键词： air-coupled ultrasonic transducer,noncontact,photoacoustic imaging,burn injury,vasculature
更新于2025-09-11 14:15:04
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Quantitative Study of the Macular Microvasculature in Human Donor Eyes
摘要： PURPOSE. To precisely quantify the macular microvasculature density using microperfusion and labeling techniques in human donor eyes. Such information may be useful in understanding the role of the macular microvasculature in coping with the metabolic requirements of the neurons in this densely packed region, and provide a reference point for clinical studies using recently developed optical imaging techniques. METHODS. The macular microvasculature was perfusion-labeled in 18 human donor eyes and optical stacks collected from regions superior, temporal, inferior, and nasal to the foveola using confocal microscopy. The optical slices were separated into the deep macula vascular layer (DL), and the super?cial layer (SL) in which all the vessels super?cial to the deep macular vessel layer were included. The DL and SL images were analyzed and vessel density measured according to their orientation from the foveola and in foveal and parafoveal regions. Vessel densities were compared across regions and age groups. RESULTS. Both the SL and DL showed an increase in vessel density with increasing eccentricity from the foveal to parafoveal regions. Vessel density was found to rank in the order of inferior > superior > temporal > nasal in both SL and DL layers. The SL vascular density was approximately 31%, whereas DL was approximately 17%. The DL was planar in nature and density not affected by age. Age-related increase in vessel density was observed in the SL. CONCLUSIONS. Microperfusion and labeling techniques in combination with confocal microscopy has enabled collection of reliable data on vascular density in the macula region. Regional differences may re?ect well-matched vascular supply and neuronal demands. Age-related changes might indicate the importance of stable blood supply for the human macula.
关键词： human,macula,retinal vasculature
更新于2025-09-04 15:30:14
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Comparison of Common Retinal Vessel Caliber Measurement Software and a Conversion Algorithm
摘要： Purpose: To compare three commonly used retinal vessel caliber measurement software systems, and propose an algorithm for conversion between measurement systems. Methods: We used 120 retinal photographs to evaluate the agreement between three commonly used software (Retinal Analysis [RA], Integrative Vessel Analysis [IVAN], and Singapore I Vessel Assessment [SIVA]). Bland-Altman plots were used to evaluate agreement of retinal arteriolar (central retinal artery equivalent, CRAE) and venular (central retinal vein equivalent, CRVE) calibers. Pearson’s correlation was used to assess the associations between systemic factors and retinal vessel calibers, and Z-test was used to compare the strength of the correlation coefficients across the three software systems. An algorithm was created to convert measurements, with paired t-test performed to evaluate the differences between SIVA-measured retinal calibers and SIVA-approximates converted from RA- and IVAN-measurements using the algorithm. Results: Differences between SIVA- and RA-measured calibers (CRAE: mean difference [MD] ? (cid:2)21.8 lm, 95% limits of agreement [LOA], (cid:2)47.3 to 3.7 lm; CRVE: MD ? (cid:2)7.7 lm, 95% LOA, (cid:2)28.0 to 12.6 lm), SIVA- and IVAN-measured calibers (CRAE: MD ? (cid:2)6.7 lm, 95% LOA, (cid:2)23.8 to 10.4 lm; CRVE: MD ? (cid:2)18.2 lm 95% LOA, (cid:2)36.7 to 0.4 lm) were large. However, the strength of correlations between systemic factors with SIVA-measured retinal calibers was not significantly different to that measured using RA and IVAN (P (cid:3) 0.332). SIVA-approximates converted from RA and IVAN measurements using the proposed algorithm was not significantly different from SIVA-measured calibers (P (cid:3) 0.20). Conclusion: Absolute measurements of retinal vessel calibers vary between three common software systems but associations with systemic factors were similar. Translational Relevance: The proposed algorithm allowed conversions of RA and IVAN measurements to SIVA-approximates. This conversion is important for future data pooling and establishment of normative values for retinal vascular caliber measurements.
关键词： retinal vasculature,epidemiology,retinal vessels
更新于2025-09-04 15:30:14
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Neuronal Expression of Junctional Adhesion Molecule-C is Essential for Retinal Thickness and Photoreceptor Survival
摘要： Background: Photoreceptor cell death is a key pathology of retinal degeneration diseases. To date, the molecular mechanisms for this pathological process remain largely unclear. Junctional adhesion molecule-c (Jam-c) has been shown to play important roles in different biological events. However, its effect on retinal neuronal cells is unknown. Objective: To determine the effect of Jam-c on adult mouse eyes, particularly, on retinal structure, vasculature and photoreceptor cells, in order to explore potential important target molecules for ocular diseases. Methods: Jam-c global knockout mice, endothelial-specific and neuronal-specific Jam-c conditional knockout mice using Tie2-Cre and Nestin-Cre mice respectively were used in this study. Mouse eyes were harvested from the different groups and eye size examined. Cryosections of the eyes were made and stained with Hematoxylin and Eosin (H&E) and the thicknesses of retinal layers measured. Retinal blood vessels and cone and rod photoreceptors were analyzed using isolectin B4, peanut agglutinin and rhodopsin as markers respectively. In vivo Jam-c knockdown in mouse eyes was performed by intravitreal injection of Jam-c shRNA. Jam-c expression in the retinae was quantified by real-time PCR. Results: Global Jam-c gene deletion in mice resulted in smaller eyes and decreased the diameters of lens and iris. Jam-c-/- mice display marked thinning of the outer nuclear layer (ONL), less numbers of photoreceptor cells, and abnormal retinal vasculature. Importantly, neuronal-specific Jam-c deletion led to similar phenotype, whereas no obvious defect was observed in endothelial-specific Jam-c knockout mice. Moreover, Jam-c knockdown by shRNA also decreased ONL thickness and photoreceptor numbers. Conclusion: We found that Jam-c is critically required for the normal size and retinal structure. Particularly, Jam-c plays important roles in maintaining the normal retinal thickness, vasculature and photoreceptor numbers. Jam-c thus may therefore have important roles in various ocular diseases.
关键词： retina,photoreceptor degeneration,neuroprotection.,vasculature,Junctional adhesion molecule-c
更新于2025-09-04 15:30:14