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Analysis of blood and dialysate flow in a hemodialyzer by perfusion computed tomography

Analysis of blood and dialysate flow in a hemodialyzer by pe...

World Congress on Medical Physics and biomedical engineering: Diagnostic and Therapeutic Instrumentation, Clinical engineering

作者： Kim, J.C. Kim, J.H. Kim, H.-C. Kang, E. Ronco, C. Kim, H.C. Institute of Medical and Biological Engineering College of Medicine Seoul National University Seoul Korea Republic of Interdisciplinary Program in Bioengineering Major Seoul National University Seoul Korea Republic of Department of Radiology Seoul National University Hospital Seoul Korea Republic of Department of Internal Medicine Chung-Ang University Hospital Seoul Korea Republic of Vincenza Italy Department of Biomedical Engineering College of Medicine Seoul National University 28 Yeongeon-dong Jongno-gu Seoul 110-744 Korea Republic of

ISBN: (纸本)9783642038846

Perfusion computed tomography (PCT) is a means to rapidly and easily evaluate cerebral perfusion in patients presenting with acute stroke symptoms, which pro-vides insights into capillary-level hemodynamics. In this study, we used PCT to analyze the 3-dimensional blood and dialysate flow in a low-flux hemodialyzer equipped with a standard fiber bundle. The dynamic CT studies were performed with 64-channel multi-detector row CT (MDCT) at a dialysate flow rate of 500 ml/min and a 1.0 ml/sec injection rate of contrast agent. Central volume principle was used to calculate hydro-dynamic parameters by deconvolution of time-density curves (TDCs). Functional maps of PCT parameters quantitatively described the blood and dialysate flow maldistribution, varia-tions in fiber packing, and perfusion pressure distribution in a hemodialyzer. PCT was able to overcome the limitations of conventional imaging techniques for analyzing dialysate flow distributions in hollow-fiber dialyzers. Therefore, PCT is a quantitative analysis method to provide better insights into hemodynamics of hollow-fiber dialyzers and is expected to contribute to optimization of artificial kidneys. © 2009 Springer-Verlag.

关键词： Computerized tomography

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A neural network classifier for the automatic interpretation of epileptogenic zones in F-18FDG brain PET

A neural network classifier for the automatic interpretation...

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Annual International Conference of the IEEE engineering in Medicine and Biology Society (EMBC)

作者： Jae Sung Lee Seok-Ki Kim Dong Soo Lee Myung Chul Lee Kwang Suk Park Interdisciplinary Program in Medical and Biological Engineering Major Seoul National University Seoul South Korea Department of Nuclear Medicine College of Medicine Seoul National University Seoul South Korea Department of Biomedical Engineering College of Medicine Seoul National University Seoul South Korea

For the objective interpretation of cerebral metabolic patterns in epilepsy patients, we developed a computer-aided classifier using artificial neural network. We studied interictal brain FDG PET scans of 257 epilepsy patients which were diagnosed as normal (n=64), left temporal lobe epilepsy (n=112), or right temporal robe epilepsy (n=81) by visual interpretation. Automatically segmented volumes of interest (VOI) were used to reliably extract the features representing patterns of cerebral metabolism. All images were spatially normalized to MNI standard PET template and smoothed with 16 mm FWHM Gaussian kernel using SPM96. Mean count in cerebral region was normalized. The VOI for 34 cerebral regions were previously defined on the standard template and 17 different counts of mirrored regions to hemispheric midline were extracted from spatially normalized images. A three-layer feedforward error backpropagation neural network classifier with 17 input nodes and 3 output nodes was used. The network was trained to interpret metabolic patterns and produce identical diagnoses with those of expert viewers. The performance of the neural network was optimized by testing with 5/spl sim/40 nodes in hidden layer. Randomly selected 40 images from each group were used to train the network and the remainders were used to test the learned network. The optimized neural network gave a maximum agreement rate of 80.3% with expert viewers. It used 20 hidden nodes and was trained for 1508 epochs. Also, neural network gave agreement rates of 75/spl sim/80% with 10 or 30 nodes in hidden layer. We conclude that artificial neural network performed as well as human experts and could be potentially useful tool as clinical decision supporting tool for the localization of epileptogenic zones.

关键词： Neural networks Biological neural networks Artificial neural networks Epilepsy Positron emission tomography Testing Computer networks Temporal lobe Image segmentation Computer network reliability

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Cartilaginous tissue formation with an elastic PLCL scaffold and human adipose tissue-derived stromal cells

Cartilaginous tissue formation with an elastic PLCL scaffold...

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作者： Lee, So Eun Jung, Youngmee Kim, Soo Hyun Kim, Sang-Heon Rhie, Jong Won Kim, Young Ha Min, Byoung Goo Biomaterials Research Center Korea Institute of Science and Technology P.O. Box 131 Cheonryang Seoul 130-650 Korea Republic of Interdisciplinary Program Medical and Biological Engineering Major Seoul National University 28 Yeongeon Jongro Seoul 110-744 Korea Republic of Department of Plastic Surgery Catholic University 505 Banpo Seocho Seoul 137-701 Korea Republic of Department of Materials Science and Engineering Gwangju Institute of Science and Technology 1 Oryong- Buk Gwangju 500-712 Korea Republic of Department of Biomedical Engineering Seoul National University 28 Yeongeon Jongro Seoul 110-744 Korea Republic of

In cartilage tissue engineering, as a cell source, adult stem cells are very attractive for clinical applications. Recent studies suggest that human adipose tissue-derived stromal cells (ASCs) have multilineage potential similar to bone marrow-derived stromal cells (BMSCs). ASCs are obtained from adipose tissue easily isolated by suction-assisted lipectomy in various body parts. Also, as one of major factors of cartilage tissue engineering, scaffolds have an important role in cartilage formation. Poly(L-lactide-co-Ε-carprolactone) scaffolds have physiological activity, biodegradability, high cell affinity, and mechano-activity. The object of this study is cartilaginous tissue formation using highly elastic PLCL scaffolds and ASCs in vitro and in vivo. Poly(L-lactide-co-Ε-carprolactone) copolymers were synthesized from lactide and Ε-carprolactone in the presence of stannous octoate as catalyst. The scaffolds with 85% porosity and 300-500μm pore size were fabricated by gel-pressing method. ASCs were seeded on scaffolds and cultured for 21days in vitro. Cell/polymer constructs were characterized by reverse transcriptase-polymerase chain reaction for confirming differentiation to chondrocytes onto PLCL scaffolds. Also, for examining cartilaginous tissue formation in vivo, ASCs seeded scaffolds which were induced chondrogenesis for 2 weeks were implanted in nude mice subcutaneously for up to 8weeks. Histological studies showed that implants partially developed cartilaginous tissue within lacunae. And there was an accumulation of sulfated glycoaminoglycans. Immunohistochemical analysis revealed that implants were positively stained for specific extracellular matrix. These results indicate that ASCs and PLCL scaffols could be used to cartilage tissue engineering.

关键词： Tissue engineering

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Segmented readout for Cherenkov time-of-flight positron emission tomography detectors based on bismuth germanate

arXiv

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arXiv 2024年

作者： Yi, Minseok Lee, Daehee Gola, Alberto Merzi, Stefano Penna, Michele Lee, Jae Sung Cherry, Simon R. Kwon, Sun Il Department of Biomedical Engineering University of California Davis United States Interdisciplinary Program in Bioengineering College of Engineering Seoul National Graduate School Korea Republic of Integrated Major in Innovative Medical Science Seoul National Graduate School Korea Republic of Fondazione Bruno Kessler Italy Brightonix Imaging Inc. Korea Republic of

Positron emission tomography (PET) is the most sensitive biomedical imaging modality for noninvasively detecting and visualizing positron-emitting radiopharmaceuticals within a subject. In PET, measuring the time-of-flight (TOF) information for each pair of 511-keV annihilation photons improves effective sensitivity but requires high timing resolution. Hybrid materials that emit both scintillation and Cherenkov photons, such as bismuth germanate (BGO), recently offer the potential for more precise timing information from Cherenkov photons while maintaining adequate energy resolution from scintillation photons. However, a significant challenge in using such hybrid materials for TOF PET applications lies in the event-dependent timing spread caused by the mixed detection of Cherenkov and scintillation photons due to relatively lower production of Cherenkov photons. This study introduces an innovative approach by segmenting silicon photomultiplier (SiPM) pixels coupled to a single crystal, rather than using traditional SiPMs that are as large as or larger than the crystals they read. We demonstrated that multiple time stamps and photon counts obtained from the segmented SiPM can classify events by providing temporal photon density, effectively addressing this challenge. The approach and findings would lead to new opportunities in applications that require precise timing and photon counting, spanning the fields of medical imaging, high-energy physics, and optical physics. © 2024, CC BY.

关键词： Photons

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Mechano-active cartilage tissue engineering: The effect of dynamic compressive stimulation

Mechano-active cartilage tissue engineering: The effect of d...

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作者： Jung, Youngmee Kim, Soo Hyun Kim, Sang-Heon Kim, Young Ha Xie, Jun Matsuda, Takehisa Min, Byoung Goo Biomaterials Research Center Korea Institute of Science and Technology P.O.Box 131 Cheongryang Seoul 130-650 Korea Republic of Interdisciplinary Program Medical and Biological Engineering Major Seoul National University 28 Yeongeon Chongro Seoul 110-790 Korea Republic of Department of Materials Science and Engineering Gwangju Institute of Science and Technology 1 Oryang Buk Gwangju 500-712 Korea Republic of Department of Orthopaedic Surgery School of Medicine Fukuoka University 8-19-1 Nanakuma Jonan Fukuoka 814-0180 Japan Genome and Biomedical Engineering Laboratory Kanazawa Institute of Technology 7-1 Ohgigaoka Nonoichi Ishikawa 921 - 8501 Japan Department of Biomedical Engineering Seoul National University 28 Yeongeon Chongro Seoul 110-790 Korea Republic of

Mechano-active scaffolds were fabricated from very elastic poly(lactide-co-carprolactone) by a gel-pressing method. The scaffolds were seeded with bone marrow stromal cells and the continuous compressive deformation was applied to cell-polymer constructs in the chondrogenic media. Then, they were implanted in nude mice subcutaneously to evaluate for the effect of dynamic compression for regeneration of cartilage. From the biochemical analyses, chondrogenic differentiation was sustained and enhanced significantly and chondral extracellular matrix was increased through mechanical stimulation. Histological analyses showed that implants stimulated mechanically formed mature and well-developed cartilaginous tissue, as evidenced by bone marrow derived chondrocytes within lacunae. Consequently, the periodic application of dynamic compression can encourage bone marrow stromal cells to differentiation to chondrogenic lineage and to maintain their phenotypes.

关键词： Cartilage

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LoraMap: Harnessing the Power of LoRA Connections

arXiv

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arXiv 2024年

作者： Park, Hyeryun Kwak, Jeongwon Jang, Dongsuk Park, Sumin Choi, Jinwook Interdisciplinary Program for Bioengineering Graduate School Seoul National University Korea Republic of Integrated Major in Innovative Medical Science Graduate School Seoul National University Korea Republic of Department of Biomedical Engineering College of Medicine Seoul National University Korea Republic of Medical Research Center Institute of Medical and Biological Engineering Seoul National University Korea Republic of

Fact-checking techniques can mitigate hallucinations in Large Language Models (LLMs), a prominent issue in specialized domains. As parameter-efficient techniques such as Low-Rank Adaptation (LoRA) can overcome substantial computational overhead, some studies have explored the integration of multiple LoRAs. While previous studies focus on parallel integration, this paper investigates methods to establish connections among multiple LoRAs. We create three reasoning datasets tailored to fact-checking and fine-tune individual LoRAs, allowing them to view and reason from diverse perspectives. Then, we explore strategies for allocating these reasoning LoRAs and introduce LoraMap, an approach to map connections between them. The results of the fact-checking task demonstrate that the performance of LoraMap is superior to LoraHub, an existing method for integrating LoRAs. LoraMap also outperforms with significantly fewer trainable parameters than LoraConcat, which concatenates LoRAs and further fine-tunes them. Copyright © 2024, The Authors. All rights reserved.

关键词： Problem oriented languages

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Automated Information Extraction from Thyroid Operation Narrative: A Comparative Study of GPT-4 and Fine-tuned KoELECTRA

arXiv

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arXiv 2024年

作者： Jang, Dongsuk Park, Hyeryun Son, Jiye Hwang, Hyeonuk Kim, Su-Jin Choi, Jinwook Interdisciplinary Program Bioengineering Major Seoul National University Korea Republic of Seoul National University Korea Republic of Department of Surgery Ewha Womans University Medical Center Korea Republic of Department of Surgery Seoul National University Hospital College of Medicine Korea Republic of Department of Biomedical Engineering College of Medicine Seoul National University Korea Republic of

In the rapidly evolving field of healthcare, the integration of artificial intelligence (AI) has become a pivotal component in the automation of clinical workflows, ushering in a new era of efficiency and accuracy. This study focuses on the transformative capabilities of the fine-tuned KoELECTRA model in comparison to the GPT-4 model, aiming to facilitate automated information extraction from thyroid operation narratives. The current research landscape is dominated by traditional methods heavily reliant on regular expressions, which often face challenges in processing free-style text formats containing critical details of operation records, including frozen biopsy reports. Addressing this, the study leverages advanced natural language processing (NLP) techniques to foster a paradigm shift towards more sophisticated data processing systems. Through this comparative study, we aspire to unveil a more streamlined, precise, and efficient approach to document processing in the healthcare domain, potentially revolutionizing the way medical data is handled and analyzed. Copyright © 2024, The Authors. All rights reserved.

关键词： Automation

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Multimodal Spatial Attention Network for Automatic Head and Neck Tumor Segmentation in FDG-PET and CT Images 1

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2nd 3D Head and Neck Tumor Segmentation in PET/CT Challenge, HECKTOR 2021, held in conjunction with 24th International Conference on Medical Image Computing and Computer-Assisted Intervention, MICCAI 2021

作者： Cho, Minjeong Choi, Yujin Hwang, Donghwi Yie, Si Young Kim, Hanvit Lee, Jae Sung School of Electrical and Electronics Engineering Chung-Ang University Seoul06974 Korea Republic of Department of Biomedical Engineering Kyunghee University College of Electronics and Information 1732 Deogyeong-daero Giheung-gu Gyeonggi-do Yongin-si Korea Republic of Department of Nuclear Medicine Seoul National University College of Medicine Seoul03080 Korea Republic of Department of Biomedical Sciences Seoul National University College of Medicine Seoul03080 Korea Republic of Interdisciplinary Program in Bioengineering Seoul National University Graduate School Seoul Korea Republic of Integrated Major in Innovative Medical Science Seoul National University Graduate School Seoul Korea Republic of Ulsan Korea Republic of Artificial Intelligence Institute Seoul National University Seoul08826 Korea Republic of Brightonix Imaging Inc. Seoul04782 Korea Republic of

ISBN: (数字)9783030982539

ISBN: (纸本)9783030982522

Quantitative positron emission tomography/computed tomography (PET/CT), owing to the functional metabolic information and anatomical information of the human body that it presents, is useful to achieve accurate tumor delineation. However, manual annotation of a Volume Of Interest (VOI) is a labor-intensive and time-consuming task. In this study, we automatically segmented the Head and Neck (H&N) primary tumor in combined PET/CT images. Herein, we propose a convolutional neural network named Multimodal Spatial Attention Network (MSA-Net), supplemented with a Spatial Attention Module (SAM), which uses a PET image as an input. We evaluated this model on the MICCAI 2021 HEad and neCK TumOR (HECKTOR) segmentation challenge dataset. Our method delivered a competitive cross-validation efficiency, with Dice Similarity Coefficient (DSC) 0.757, precision 0.788, and recall 0.785. When we tested out method on test dataset, we achieved an average DSC and Hausdorff Distance at 95% (HD95) of 0.766 and 3.155 respectively. Our team name is ‘Heck_Uihak’. © 2022, Springer Nature Switzerland AG.

关键词： Tumors

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Endoscopic Vision Based Tracking of Multiple Surgical Instruments in Robot-assisted Surgery

Endoscopic Vision Based Tracking of Multiple Surgical Instru...

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International Conference on Control, Automation and Systems

作者： Jiwon Ryu Jaesoon Choi Hee Chan Kim Interdisciplinary Program Bioengineering Major Graduate School Seoul National University Asan Institute for Life Sciences University of Ulsan College of Medicine and Asan Medical Center Department of Biomedical Engineering College of Medicine and Institute of Medical and Biological Engineering Medical Research Center Seoul National University

ISBN: (纸本)9781467322478

Robot-assisted cardiac surgeries are effective for operations in limited spaces. Enhancement in safety functions based on automatic tracking of surgical instrument position to prevent inadvertent harmful events as cardiac tissue perforation and instrument collisions can be meaningful augmentation to current robot surgery system. A vision based instrument tracking scheme as a core algorithm to implement such assistive functions has been developed in this study. Through a chain of computer vision techniques, including classification of metallic properties using k-means clustering and instrument movement tracking using similarity measure, Euclidean distance calculation, and Kalman filter algorithm, an automatic tracking scheme has been proposed and the implemented system showed satisfactory performance in tests using real robot-assisted surgery videos. Trajectory comparisons of automatically detected data and ground truth data obtained by manually locating the center of mass of each instrument were used to quantitatively validate the system. The developed algorithm could provide valuable information to clinicians for safer operation.

关键词： Surgical instrument tracking Robot-assisted Surgery Multiple object tracking Collision warning

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Ionic Circuits Based on Polyelectrolyte Diodes on a Microchip†

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Angewandte Chemie 2009年第21期121卷

作者： Ji‐Hyung Han Kwang Bok Kim Hee Chan Kim Taek Dong Chung Department of Chemistry Seoul National University Seoul 151‐747 (Korea) Fax: (+82) 887‐4354 http://www.niel.or.kr/ Interdisciplinary Program Bioengineering Major Seoul National University Seoul 110‐744 (Korea) Department of Biomedical Engineering College of Medicine and Institute of Medical and Biological Engineering Medical Research Center Seoul National University Seoul 110‐744 (Korea)

Bei Grün gehen : Eine Polyelektrolytdiode auf einem Mikrochip zeigt ein eindeutiges nichtlineares Gleichrichterverhalten. Mit diesem System lässt sich in Echtzeit die dynamische Verteilung von Ionen in einer geladenen Polymerphase im elektrischen Feld mithilfe von Fluoreszenzbildern visualisieren. Mehrere Polyelektrolytdioden wurden auf einem Mikrochip integriert, um vielfältige Logikgatter auf Basis ionischer Schaltkreise herzustellen (siehe Bild).

关键词： Fluoreszenz Gleichrichter Ionische Schaltkreise Mikrochips Polyelektrolyte

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