64 results on '"Sheet D"'
Search Results
2. Spatiotemporal deep networks for detecting abnormality in videos
- Author
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Sharma, M. K., Sheet, D., and Biswas, P. K.
- Published
- 2020
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3. Local instance and context dictionary-based detection and localization of abnormalities
- Author
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Sharma, M. K., Sheet, D., and Biswas, P. K.
- Published
- 2021
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4. Image Embedding for Detecting Irregularity
- Author
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Sharma, M. K., primary, Sheet, D., additional, and Biswas, Prabir Kumar, additional
- Published
- 2019
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5. Domain Adapted Model for In Vivo Intravascular Ultrasound Tissue Characterization
- Author
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Conjeti, S., primary, Roy, A.G., additional, Sheet, D., additional, Carlier, S., additional, Syeda-Mahmood, T., additional, Navab, N., additional, and Katouzian, A., additional
- Published
- 2017
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6. Contributors
- Author
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Adriaenssens, T., primary, Beier, S., additional, Berg, P., additional, Bigras, J.-L., additional, Bonnefous, O., additional, Burgner, D., additional, Carlier, S., additional, Cater, J., additional, Chen, K.Y.H., additional, Conjeti, S., additional, Cowan, B., additional, Dahdah, N., additional, Daniels, L.B., additional, Daróczy, L., additional, Demirci, S., additional, Doblado, C., additional, Fallavollita, P., additional, Flórez-Valencia, L., additional, Gastounioti, A., additional, Ghotbi, R., additional, Golemati, S., additional, Houissa, K., additional, Idris, N., additional, Janiga, G., additional, Kabongo, L., additional, Katouzian, A., additional, Kermani, A., additional, Kowarschik, M., additional, Legarreta, J.H., additional, López-Linares, K., additional, Macía, I., additional, Mansour, R., additional, Maurice, R.L., additional, Medrano-Gracia, P., additional, Mermigkas, P., additional, Morales, H.G., additional, Navab, N., additional, Norris, S., additional, Nikita, K.S., additional, Orkisz, M., additional, Ormiston, J., additional, Pourmodheji, A., additional, Prevenios, M., additional, Ranjbarnavazi, S.M., additional, Rigla, J., additional, Roy, A.G., additional, Sheet, D., additional, Syeda-Mahmood, T., additional, Taki, A., additional, Ughi, G.J., additional, Vaujois, L., additional, Webster, M., additional, and Young, A., additional
- Published
- 2017
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7. IROS 2019 Lifelong Robotic Vision: Object Recognition Challenge
- Author
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Bae H., Brophy E., Chan R. H. M., Chen B., Feng F., Graffieti G., Goel V., Hao X., Han H., Kanagarajah S., Kumar S., Lam S. -K., Lam T. L., Lan C., Liu Q., Lomonaco V., Ma L., Maltoni D., Parisi G. I., Pellegrini L., Piyasena D., Pu S., She Q., Sheet D., Song S., Son Y., Wang Z., Ward T. E., Wu J., Wu M., Xie D., Xu Y., Yang L., Yang Q., Zhong Q., Zhou L., Bae H., Brophy E., Chan R.H.M., Chen B., Feng F., Graffieti G., Goel V., Hao X., Han H., Kanagarajah S., Kumar S., Lam S.-K., Lam T.L., Lan C., Liu Q., Lomonaco V., Ma L., Maltoni D., Parisi G.I., Pellegrini L., Piyasena D., Pu S., She Q., Sheet D., Song S., Son Y., Wang Z., Ward T.E., Wu J., Wu M., Xie D., Xu Y., Yang L., Yang Q., Zhong Q., and Zhou L.
- Subjects
Lifelong Learning, Continual Learning, Robotics, Challenge - Abstract
Humans have a remarkable ability to learn continuously from th e environment and inner experience. One of the grand goals of robots is to build an artificial "lifelong learning" agent that can shape a cultivated understanding of the world from the current scene and previous knowledge via an autonomous lifelong development. It is challenging for the robot learning process to retain earlier knowledge when robots encounter new tasks or information. Recent advances in computer vision and deep -learning methods have been impressive due to large-scale data sets, such as ImageNet and COCO. However, robotic vision poses unique new challenges for applying visual algorithms developed from these computer vision data sets because they implicitly assume a fixed set of categories and time -invariant task distributions.
- Published
- 2020
8. Sickle Cell Disease Severity Prediction from Percoll Gradient Images Using Graph Convolutional Networks
- Author
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Albarqouni, Shadi, Cardoso, M. Jorge, Dou, Qi, Kamnitsas, Konstantinos, Khanal, Bishesh, Rekik, Islem, Rieke, Nicola, Sheet, Debdoot, Tsaftaris, Sotirios, Xu, Daguang, Xu, Ziyue, Albarqouni, S ( Shadi ), Cardoso, M J ( M. Jorge ), Dou, Q ( Qi ), Kamnitsas, K ( Konstantinos ), Khanal, B ( Bishesh ), Rekik, I ( Islem ), Rieke, N ( Nicola ), Sheet, D ( Debdoot ), Tsaftaris, S ( Sotirios ), Xu, D ( Daguang ), Xu, Z ( Ziyue ), Sadafi, Ario, Makhro, Asya, Livshits, Leonid, Navab, Nassir, Bogdanova, Anna; https://orcid.org/0000-0003-0502-5381, Marr, Carsten, Albarqouni, Shadi, Cardoso, M. Jorge, Dou, Qi, Kamnitsas, Konstantinos, Khanal, Bishesh, Rekik, Islem, Rieke, Nicola, Sheet, Debdoot, Tsaftaris, Sotirios, Xu, Daguang, Xu, Ziyue, Albarqouni, S ( Shadi ), Cardoso, M J ( M. Jorge ), Dou, Q ( Qi ), Kamnitsas, K ( Konstantinos ), Khanal, B ( Bishesh ), Rekik, I ( Islem ), Rieke, N ( Nicola ), Sheet, D ( Debdoot ), Tsaftaris, S ( Sotirios ), Xu, D ( Daguang ), Xu, Z ( Ziyue ), Sadafi, Ario, Makhro, Asya, Livshits, Leonid, Navab, Nassir, Bogdanova, Anna; https://orcid.org/0000-0003-0502-5381, and Marr, Carsten
- Abstract
Sickle cell disease (SCD) is a severe genetic hemoglobin disorder that results in premature destruction of red blood cells. Assessment of the severity of the disease is a challenging task in clinical routine, since the causes of broad variance in SCD manifestation despite the common genetic cause remain unclear. Identification of biomarkers that would predict the severity grade is of importance for prognosis and assessment of responsiveness of patients to therapy. Detection of the changes in red blood cell (RBC) density by means of separation of Percoll density gradients could be such a marker as it allows to resolve intercellular differences and follow the most damaged dense cells prone to destruction and vasoocclusion. Quantification and interpretation of the images obtained from the distribution of RBCs in Percoll gradients is an important prerequisite for establishment of this approach. Here, we propose a novel approach combining a graph convolutional network, a convolutional neural network, fast Fourier transform, and recursive feature elimination to predict the severity of SCD directly from a Percoll image. Two important but expensive laboratory blood test parameters are used for training the graph convolutional network. To make the model independent from such tests during prediction, these two parameters are estimated by a neural network from the Percoll image directly. On a cohort of 216 subjects, we achieve a prediction performance that is only slightly below an approach where the groundtruth laboratory measurements are used. Our proposed method is the first computational approach for the difficult task of SCD severity prediction. The two-step approach relies solely on inexpensive and simple blood analysis tools and can have a significant impact on the patients’ survival in low resource regions where access to medical instruments and doctors is limited.
- Published
- 2021
9. Brightness preserving dynamic fuzzy histogram equalization
- Author
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Sheet, D., Garud, H., and Suveer, A.
- Subjects
Image processing -- Analysis ,Fuzzy algorithms -- Analysis ,Fuzzy logic -- Analysis ,Fuzzy systems -- Analysis ,Fuzzy logic ,Business ,Electronics and electrical industries ,Engineering and manufacturing industries - Published
- 2010
10. Chapter 7 - Domain Adapted Model for In Vivo Intravascular Ultrasound Tissue Characterization
- Author
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Conjeti, S., Roy, A.G., Sheet, D., Carlier, S., Syeda-Mahmood, T., Navab, N., and Katouzian, A.
- Published
- 2017
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11. Detection of retinal vessels in fundus images through transfer learning of tissue specific photon interaction statistical physics
- Author
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Sheet, D., primary, Karri, S.P.K., additional, Conjeti, S., additional, Ghosh, S., additional, Chatterjee, J., additional, and Ray, A.K., additional
- Published
- 2013
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12. Iterative Self-Organizing Atherosclerotic Tissue Labeling in Intravascular Ultrasound Images and Comparison With Virtual Histology
- Author
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Katouzian, A., primary, Karamalis, A., additional, Sheet, D., additional, Konofagou, E., additional, Baseri, B., additional, Carlier, S. G., additional, Eslami, A., additional, Konig, Andreas, additional, Navab, N., additional, and Laine, A. F., additional
- Published
- 2012
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13. Realization and simulation of the hardware for RFID system and its performance study
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Sheet, D., primary, Kumar, A., additional, Dutta, A., additional, Dasgupta, S., additional, Datta, T., additional, and Sarkar, S.K., additional
- Published
- 2007
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14. Volume visualization approach for depth-of-field extension in digital pathology.
- Author
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Garud, H., Ray, A.K., Mandal, S., Sheet, D., Mahadevappa, M., and Chatterjee, J.
- Published
- 2011
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15. Brightness preserving contrast enhancement in digital pathology.
- Author
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Garud, H., Sheet, D., Suveer, A., Karri, P.K., Ray, A.K., Mahadevappa, M., and Chatterjee, J.
- Published
- 2011
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16. Image quality assessment for performance evaluation of despeckle filters in Optical Coherence Tomography of human skin.
- Author
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Sheet, D., Pal, S., Chakraborty, A., Chatterjee, J., and Ray, A.K.
- Published
- 2010
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17. Comparative evaluation of speckle reduction algorithms in optical coherence tomography.
- Author
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Pal, S., Sheet, D., Chakraborty, A., and Chatterjee, J.
- Published
- 2010
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18. Evaluation of p63 expression in Oral Sub-mucous Fibrosis.
- Author
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Das, R.K., Venkatraghavan, V., Sheet, D., Chakraborty, C., Ray, A.K., Chatterjee, J., Pal, M., and Paul, R.R.
- Published
- 2010
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19. Visual importance pooling for image quality assessment of despeckle filters in Optical Coherence Tomography.
- Author
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Sheet, D., Pal, S., Chakraborty, A., Chatterjee, J., and Ray, A.K.
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- 2010
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20. CholecTriplet2022: Show me a tool and tell me the triplet - An endoscopic vision challenge for surgical action triplet detection.
- Author
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Nwoye CI, Yu T, Sharma S, Murali A, Alapatt D, Vardazaryan A, Yuan K, Hajek J, Reiter W, Yamlahi A, Smidt FH, Zou X, Zheng G, Oliveira B, Torres HR, Kondo S, Kasai S, Holm F, Özsoy E, Gui S, Li H, Raviteja S, Sathish R, Poudel P, Bhattarai B, Wang Z, Rui G, Schellenberg M, Vilaça JL, Czempiel T, Wang Z, Sheet D, Thapa SK, Berniker M, Godau P, Morais P, Regmi S, Tran TN, Fonseca J, Nölke JH, Lima E, Vazquez E, Maier-Hein L, Navab N, Mascagni P, Seeliger B, Gonzalez C, Mutter D, and Padoy N
- Subjects
- Humans, Endoscopy, Algorithms, Surgical Instruments, Artificial Intelligence, Surgery, Computer-Assisted methods
- Abstract
Formalizing surgical activities as triplets of the used instruments, actions performed, and target anatomies is becoming a gold standard approach for surgical activity modeling. The benefit is that this formalization helps to obtain a more detailed understanding of tool-tissue interaction which can be used to develop better Artificial Intelligence assistance for image-guided surgery. Earlier efforts and the CholecTriplet challenge introduced in 2021 have put together techniques aimed at recognizing these triplets from surgical footage. Estimating also the spatial locations of the triplets would offer a more precise intraoperative context-aware decision support for computer-assisted intervention. This paper presents the CholecTriplet2022 challenge, which extends surgical action triplet modeling from recognition to detection. It includes weakly-supervised bounding box localization of every visible surgical instrument (or tool), as the key actors, and the modeling of each tool-activity in the form of ‹instrument, verb, target› triplet. The paper describes a baseline method and 10 new deep learning algorithms presented at the challenge to solve the task. It also provides thorough methodological comparisons of the methods, an in-depth analysis of the obtained results across multiple metrics, visual and procedural challenges; their significance, and useful insights for future research directions and applications in surgery., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)
- Published
- 2023
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21. CholecTriplet2021: A benchmark challenge for surgical action triplet recognition.
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Nwoye CI, Alapatt D, Yu T, Vardazaryan A, Xia F, Zhao Z, Xia T, Jia F, Yang Y, Wang H, Yu D, Zheng G, Duan X, Getty N, Sanchez-Matilla R, Robu M, Zhang L, Chen H, Wang J, Wang L, Zhang B, Gerats B, Raviteja S, Sathish R, Tao R, Kondo S, Pang W, Ren H, Abbing JR, Sarhan MH, Bodenstedt S, Bhasker N, Oliveira B, Torres HR, Ling L, Gaida F, Czempiel T, Vilaça JL, Morais P, Fonseca J, Egging RM, Wijma IN, Qian C, Bian G, Li Z, Balasubramanian V, Sheet D, Luengo I, Zhu Y, Ding S, Aschenbrenner JA, van der Kar NE, Xu M, Islam M, Seenivasan L, Jenke A, Stoyanov D, Mutter D, Mascagni P, Seeliger B, Gonzalez C, and Padoy N
- Subjects
- Humans, Algorithms, Operating Rooms, Workflow, Deep Learning, Benchmarking, Laparoscopy
- Abstract
Context-aware decision support in the operating room can foster surgical safety and efficiency by leveraging real-time feedback from surgical workflow analysis. Most existing works recognize surgical activities at a coarse-grained level, such as phases, steps or events, leaving out fine-grained interaction details about the surgical activity; yet those are needed for more helpful AI assistance in the operating room. Recognizing surgical actions as triplets of ‹instrument, verb, target› combination delivers more comprehensive details about the activities taking place in surgical videos. This paper presents CholecTriplet2021: an endoscopic vision challenge organized at MICCAI 2021 for the recognition of surgical action triplets in laparoscopic videos. The challenge granted private access to the large-scale CholecT50 dataset, which is annotated with action triplet information. In this paper, we present the challenge setup and the assessment of the state-of-the-art deep learning methods proposed by the participants during the challenge. A total of 4 baseline methods from the challenge organizers and 19 new deep learning algorithms from the competing teams are presented to recognize surgical action triplets directly from surgical videos, achieving mean average precision (mAP) ranging from 4.2% to 38.1%. This study also analyzes the significance of the results obtained by the presented approaches, performs a thorough methodological comparison between them, in-depth result analysis, and proposes a novel ensemble method for enhanced recognition. Our analysis shows that surgical workflow analysis is not yet solved, and also highlights interesting directions for future research on fine-grained surgical activity recognition which is of utmost importance for the development of AI in surgery., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)
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- 2023
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22. Iron(II)-α-keto acid complexes of tridentate ligands on gold nanoparticles: the effect of ligand geometry and immobilization on their dioxygen-dependent reactivity.
- Author
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Bera A, Sheet D, and Paine TK
- Subjects
- Gold, Ligands, Oxygen chemistry, Keto Acids, Oxidants, Ferrous Compounds chemistry, Iron chemistry, Metal Nanoparticles
- Abstract
Two mononuclear nonheme iron(II)-benzoylformate (BF) complexes [(6Me
2 -Me-BPA)Fe(BF)](ClO4 ) (1a) and [(6Me3 -TPMM)Fe(BF)](ClO4 ) (1b) of tridentate nitrogen donor ligands, bis((6-methylpyridin-2-yl)methyl)( N -methyl)amine (6Me2 -Me-BPA) and tris(2-(6-methyl)pyridyl)methoxymethane (6Me3 -TPMM), were isolated and characterized. The structural characterization of iron(II)-chloro complexes indicates that the ligand 6Me2 -Me-BPA binds to the iron(II) centre in a meridional fashion, whereas 6Me3 -TPMM behaves as a facial ligand. Both the ligands were functionalized with terminal thiol for immobilization on gold nanoparticles (AuNPs), and the corresponding iron(II) complexes [(6Me2 -BPASH)Fe(BF)(ClO4 )]@C8 Au (2a) and [(6Me3 -TPMSH)Fe(BF)(ClO4 )]@C8 Au (2b) were prepared to probe the effect of immobilization on their ability to perform bioinspired oxidation reactions. All the complexes react with dioxygen to display the oxidative decarboxylation of the coordinated benzoylformate, but the complexes supported by 6Me3 -TPMM and its thiol-appended ligand display faster reactivity compared to their analogues with the 6Me2 -Me-BPA-derived ligands. In each case, an electrophilic iron-oxygen oxidant was intercepted as the active oxidant generated from dioxygen. The immobilized complexes (2a and 2b) display enhanced O2 -dependent reactivity in oxygen-atom transfer reactions (OAT) and hydrogen-atom transfer (HAT) reactions compared to their homogeneous congeners (1a and 1b). Furthermore, the immobilized complex 2b displays catalytic OAT reactions. This study supports that the ligand geometry and immobilization on AuNPs influence the dioxygen-dependent reactivity of the complexes.- Published
- 2023
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23. Comparison of the Effect of Propranolol Combination with Cinnarizine and Propranolol in the Prevention of Acute Migraine Attacks.
- Author
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Adeeb Sheet D, Bibani RH, and Kheder AH
- Subjects
- Adult, Humans, Female, Male, Propranolol therapeutic use, Quality of Life, Headache drug therapy, Cinnarizine therapeutic use, Migraine Disorders drug therapy, Migraine Disorders prevention & control
- Abstract
Acute migraine attacks disrupt performance and reduce the quality of life. Therefore, efforts to prevent these attacks continue using different medications. This study aimed to compare the effect of cinnarizine combination with propranolol and propranolol with placebo in preventing acute migraine attacks. This study was a semi-experimental study performed on 120 adult patients with migraine referred to Department of Neurology in Rezgary Teaching Hospital in Erbil.. Participants were randomly allocated to two groups control (propranolol) and intervention (propranolol with cinnarizine). The frequency, duration and severity of headache attacks were recorded and followed within two months. Data were analyzed with SPSS ver23 software and T-paired, independent T-tests and ANOVA. The average age of the participants was 34.54 years. 60% were female and 55% had a family history of migraine. The average frequency of headache attacks in the intervention group decreased by 75 % (from 15 times to 3 times) and a 50 % decrease in the control group (from 12 times to 6 times). The duration and severity of headaches in both intervention and control groups decreased (p <0.001), respectively. The average frequency, duration and severity of headache attacks in the first- and second months during treatment in the intervention group and control group were statistically different (p <0.001). The drug combination of propranolol with cinnarizine has an additional effect on reducing acute migraine attacks compared to propranolol alone.
- Published
- 2022
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24. Assessing Lobe-wise Burden of COVID-19 Infection in Computed Tomography of Lungs using Knowledge Fusion from Multiple Datasets.
- Author
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Visvanathan M, Balasubramanian V, Sathish R, Balasubramaniam S, and Sheet D
- Subjects
- Humans, Lung diagnostic imaging, SARS-CoV-2, Tomography, COVID-19
- Abstract
Segmentation of COVID-19 infection in the lung tissue and its quantification in individual lobes is pivotal to understanding the disease's effect. It helps to determine the disease progression and gauge the extent of medical support required. Automation of this process is challenging due to the lack of a standardized dataset with voxel-wise annotations of the lung field, lobes, and infections like ground-glass opacity (GGO) and consolidation. However, multiple datasets have been found to contain one or more classes of the required annotations. Typical deep learning-based solutions overcome such challenges by training neural networks under adversarial and multi-task constraints. We propose to train a convolutional neural network to solve the challenge while it learns from multiple data sources, each of which is annotated for only a few classes. We have experimentally verified our approach by training the model on three publicly available datasets and evaluating its ability to segment the lung field, lobes and COVID-19 infected regions. Additionally, eight scans that previously had annotations for infection and lung have been annotated for lobes. Our model quantifies infection per lobe in these scans with an average error of 4.5%.
- Published
- 2021
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25. Learning to Generate Missing Pulse Sequence in MRI using Deep Convolution Neural Network Trained with Visual Turing Test.
- Author
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Kumar V, Sharma MK, Jehadeesan R, Venkatraman B, Suman G, Patra A, Goenka AH, and Sheet D
- Subjects
- Brain, Magnetic Resonance Imaging, Signal-To-Noise Ratio, Image Processing, Computer-Assisted, Neural Networks, Computer
- Abstract
Magnetic resonance imaging (MRI) is widely used in clinical applications due to its ability to acquire a wide variety of soft tissues using multiple pulse sequences. Each sequence provides information that generally complements the other. However, factors like an increase in scan time or contrast allergies impede imaging with numerous sequences. Synthesizing images of such non acquired sequences is a challenging proposition that can suffice for corrupted acquisition, fast reconstruction prior, super-resolution, etc. This manuscript employed a deep convolution neural network (CNN) to synthesize multiple missing pulse sequences of brain MRI with tumors. The CNN is an encoder-decoder-like network trained to minimize reconstruction mean square error (MSE) loss while maximizing the adversarial attack. It inflicts on a relativistic Visual Turing Test discriminator (rVTT). The approach is evaluated through experiments performed with the Brats2018 dataset, quantitative metrics viz. MSE, Structural Similarity Measure (SSIM), and Peak Signal to Noise Ratio (PSNR). The Radiologist and MR physicist performed the Turing test with 76% accuracy, demonstrating our approach's performance superiority over the prior art. We can synthesize MR images of missing pulse sequences at an inference cost of 350.71 GFlops/voxel through this approach.
- Published
- 2021
- Full Text
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26. Cross-sectional visual comparison of remineralization efficacy of various agents on early smooth surface caries of primary teeth with swept source optical coherence tomography.
- Author
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Thomas CS, Sharma DS, Sheet D, Mukhopadhyay A, and Sharma S
- Abstract
Purpose: Sweptsource optical coherence tomography (SS-OCT) permits cross-sectional observation of surface/subsurface characteristics of enamel including early carious lesions (ECL) or remineralization non-invasively.This study aimed to visually compare the cross-sectional remineralizing efficacy of various agents on ICDAS-II scores-1&2 by using SS-OCT and histology., Methods: Baseline SS-OCT (grey-scale/false-colour) and histology was performed on the randomly selected two samples with scores-1&2. Four remineralizing agents [fluoride-varnish (FV), CPP-ACP, nanohydroxy-paste (NHP) and silver-diamine-fluoride (SDF)]were evaluated for 2-or 6-weeks post-remineralization using SS-OCT and histology., Results: Score-1&2 baseline SS-OCT images showed a linear-shaped demineralization with dentino-enamel junction (DEJ) visible; and bowl-shaped demineralization with DEJ invisible respectively. Remineralizing agents were assessed on the basis of their ability to remineralize the surface, subsurface and made visualize the DEJ in score-2. SS-OCT showed an outer growth layer in post-remineralization score-1, 2-weeks samples with FV and NHP. All the agents showed progressive subsurface remineralization in 6 weeks. Active lesions showed rapid uptake of minerals on surface. Subsurface mineralization in pigmented score-2 matched sound enamel with NHP and SDF. Surface remineralization was comparable in FV and SDF followed by NHP. SDF demonstrated deeper subsurface remineralization followed by NHP and CPP-ACP., Conclusion: SS-OCT images correlated to histology. SS-OCT could monitor surface/subsurface in-situ de/remineralization activity non-invasively ., (© 2021 Published by Elsevier B.V. on behalf of Craniofacial Research Foundation.)
- Published
- 2021
- Full Text
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27. CHAOS Challenge - combined (CT-MR) healthy abdominal organ segmentation.
- Author
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Kavur AE, Gezer NS, Barış M, Aslan S, Conze PH, Groza V, Pham DD, Chatterjee S, Ernst P, Özkan S, Baydar B, Lachinov D, Han S, Pauli J, Isensee F, Perkonigg M, Sathish R, Rajan R, Sheet D, Dovletov G, Speck O, Nürnberger A, Maier-Hein KH, Bozdağı Akar G, Ünal G, Dicle O, and Selver MA
- Subjects
- Abdomen diagnostic imaging, Humans, Liver, Algorithms, Tomography, X-Ray Computed
- Abstract
Segmentation of abdominal organs has been a comprehensive, yet unresolved, research field for many years. In the last decade, intensive developments in deep learning (DL) introduced new state-of-the-art segmentation systems. Despite outperforming the overall accuracy of existing systems, the effects of DL model properties and parameters on the performance are hard to interpret. This makes comparative analysis a necessary tool towards interpretable studies and systems. Moreover, the performance of DL for emerging learning approaches such as cross-modality and multi-modal semantic segmentation tasks has been rarely discussed. In order to expand the knowledge on these topics, the CHAOS - Combined (CT-MR) Healthy Abdominal Organ Segmentation challenge was organized in conjunction with the IEEE International Symposium on Biomedical Imaging (ISBI), 2019, in Venice, Italy. Abdominal organ segmentation from routine acquisitions plays an important role in several clinical applications, such as pre-surgical planning or morphological and volumetric follow-ups for various diseases. These applications require a certain level of performance on a diverse set of metrics such as maximum symmetric surface distance (MSSD) to determine surgical error-margin or overlap errors for tracking size and shape differences. Previous abdomen related challenges are mainly focused on tumor/lesion detection and/or classification with a single modality. Conversely, CHAOS provides both abdominal CT and MR data from healthy subjects for single and multiple abdominal organ segmentation. Five different but complementary tasks were designed to analyze the capabilities of participating approaches from multiple perspectives. The results were investigated thoroughly, compared with manual annotations and interactive methods. The analysis shows that the performance of DL models for single modality (CT / MR) can show reliable volumetric analysis performance (DICE: 0.98 ± 0.00 / 0.95 ± 0.01), but the best MSSD performance remains limited (21.89 ± 13.94 / 20.85 ± 10.63 mm). The performances of participating models decrease dramatically for cross-modality tasks both for the liver (DICE: 0.88 ± 0.15 MSSD: 36.33 ± 21.97 mm). Despite contrary examples on different applications, multi-tasking DL models designed to segment all organs are observed to perform worse compared to organ-specific ones (performance drop around 5%). Nevertheless, some of the successful models show better performance with their multi-organ versions. We conclude that the exploration of those pros and cons in both single vs multi-organ and cross-modality segmentations is poised to have an impact on further research for developing effective algorithms that would support real-world clinical applications. Finally, having more than 1500 participants and receiving more than 550 submissions, another important contribution of this study is the analysis on shortcomings of challenge organizations such as the effects of multiple submissions and peeking phenomenon., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)
- Published
- 2021
- Full Text
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28. Learning Decision Ensemble using a Graph Neural Network for Comorbidity Aware Chest Radiograph Screening.
- Author
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Chakravarty A, Sarkar T, Ghosh N, Sethuraman R, and Sheet D
- Subjects
- Comorbidity, Radiography, Research, Machine Learning, Neural Networks, Computer
- Abstract
Chest radiographs are primarily employed for the screening of cardio, thoracic and pulmonary conditions. Machine learning based automated solutions are being developed to reduce the burden of routine screening on Radiologists, allowing them to focus on critical cases. While recent efforts demonstrate the use of ensemble of deep convolutional neural networks (CNN), they do not take disease comorbidity into consideration, thus lowering their screening performance. To address this issue, we propose a Graph Neural Network (GNN) based solution to obtain ensemble predictions which models the dependencies between different diseases. A comprehensive evaluation of the proposed method demonstrated its potential by improving the performance over standard ensembling technique across a wide range of ensemble constructions. The best performance was achieved using the GNN ensemble of DenseNet121 with an average AUC of 0.821 across thirteen disease comorbidities.
- Published
- 2020
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29. A Systematic Search over Deep Convolutional Neural Network Architectures for Screening Chest Radiographs.
- Author
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Mitra A, Chakravarty A, Ghosh N, Sarkar T, Sethuraman R, and Sheet D
- Subjects
- Radiography, Reproducibility of Results, Research, Lung, Neural Networks, Computer
- Abstract
Chest radiographs are primarily employed for the screening of pulmonary and cardio-/thoracic conditions. Being undertaken at primary healthcare centers, they require the presence of an on-premise reporting Radiologist, which is a challenge in low and middle income countries. This has inspired the development of machine learning based automation of the screening process. While recent efforts demonstrate a performance benchmark using an ensemble of deep convolutional neural networks (CNN), our systematic search over multiple standard CNN architectures identified single candidate CNN models whose classification performances were found to be at par with ensembles. Over 63 experiments spanning 400 hours, executed on a 11.3 FP32 TensorTFLOPS compute system, we found the Xception and ResNet-18 architectures to be consistent performers in identifying co-existing disease conditions with an average AUC of 0.87 across nine pathologies. We conclude on the reliability of the models by assessing their saliency maps generated using the randomized input sampling for explanation (RISE) method and qualitatively validating them against manual annotations locally sourced from an experienced Radiologist. We also draw a critical note on the limitations of the publicly available CheXpert dataset primarily on account of disparity in class distribution in training vs. testing sets, and unavailability of sufficient samples for few classes, which hampers quantitative reporting due to sample insufficiency.
- Published
- 2020
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30. Lung Segmentation and Nodule Detection in Computed Tomography Scan using a Convolutional Neural Network Trained Adversarially using Turing Test Loss.
- Author
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Sathish R, Sathish R, Sethuraman R, and Sheet D
- Subjects
- Humans, Lung diagnostic imaging, Neural Networks, Computer, Radionuclide Imaging, Radiographic Image Interpretation, Computer-Assisted, Tomography, X-Ray Computed
- Abstract
Lung cancer is the most common form of cancer found worldwide with a high mortality rate. Early detection of pulmonary nodules by screening with a low-dose computed tomography (CT) scan is crucial for its effective clinical management. Nodules which are symptomatic of malignancy occupy about 0.0125 - 0.025% of volume in a CT scan of a patient. Manual screening of all slices is a tedious task and presents a high risk of human errors. To tackle this problem we propose a computationally efficient two stage framework. In the first stage, a convolutional neural network (CNN) trained adversarially using Turing test loss segments the lung region. In the second stage, patches sampled from the segmented region are then classified to detect the presence of nodules. The proposed method is experimentally validated on the LUNA16 challenge dataset with a dice coefficient of 0.984±0.0007 for 10-fold cross-validation.
- Published
- 2020
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31. A Two-Stage Multiple Instance Learning Framework for the Detection of Breast Cancer in Mammograms.
- Author
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Sarath CK, Chakravarty A, Ghosh N, Sarkar T, Sethuraman R, and Sheet D
- Subjects
- Humans, Machine Learning, Mammography, Neural Networks, Computer, Breast Neoplasms diagnostic imaging
- Abstract
Mammograms are commonly employed in the large scale screening of breast cancer which is primarily characterized by the presence of malignant masses. However, automated image-level detection of malignancy is a challenging task given the small size of the mass regions and difficulty in discriminating between malignant, benign mass and healthy dense fibro-glandular tissue. To address these issues, we explore a two-stage Multiple Instance Learning (MIL) framework. A Convolutional Neural Network (CNN) is trained in the first stage to extract local candidate patches in the mammograms that may contain either a benign or malignant mass. The second stage employs a MIL strategy for an image level benign vs. malignant classification. A global image-level feature is computed as a weighted average of patch-level features learned using a CNN. Our method performed well on the task of localization of masses with an average Precision/Recall of 0.76/0.80 and achieved an average AUC of 0.91 on the image-level classification task using a five-fold cross-validation on the INbreast dataset. Restricting the MIL only to the candidate patches extracted in Stage 1 led to a significant improvement in classification performance in comparison to a dense extraction of patches from the entire mammogram.
- Published
- 2020
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32. IDRiD: Diabetic Retinopathy - Segmentation and Grading Challenge.
- Author
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Porwal P, Pachade S, Kokare M, Deshmukh G, Son J, Bae W, Liu L, Wang J, Liu X, Gao L, Wu T, Xiao J, Wang F, Yin B, Wang Y, Danala G, He L, Choi YH, Lee YC, Jung SH, Li Z, Sui X, Wu J, Li X, Zhou T, Toth J, Baran A, Kori A, Chennamsetty SS, Safwan M, Alex V, Lyu X, Cheng L, Chu Q, Li P, Ji X, Zhang S, Shen Y, Dai L, Saha O, Sathish R, Melo T, Araújo T, Harangi B, Sheng B, Fang R, Sheet D, Hajdu A, Zheng Y, Mendonça AM, Zhang S, Campilho A, Zheng B, Shen D, Giancardo L, Quellec G, and Mériaudeau F
- Subjects
- Datasets as Topic, Humans, Pattern Recognition, Automated, Deep Learning, Diabetic Retinopathy diagnostic imaging, Diagnosis, Computer-Assisted methods, Image Interpretation, Computer-Assisted methods, Photography
- Abstract
Diabetic Retinopathy (DR) is the most common cause of avoidable vision loss, predominantly affecting the working-age population across the globe. Screening for DR, coupled with timely consultation and treatment, is a globally trusted policy to avoid vision loss. However, implementation of DR screening programs is challenging due to the scarcity of medical professionals able to screen a growing global diabetic population at risk for DR. Computer-aided disease diagnosis in retinal image analysis could provide a sustainable approach for such large-scale screening effort. The recent scientific advances in computing capacity and machine learning approaches provide an avenue for biomedical scientists to reach this goal. Aiming to advance the state-of-the-art in automatic DR diagnosis, a grand challenge on "Diabetic Retinopathy - Segmentation and Grading" was organized in conjunction with the IEEE International Symposium on Biomedical Imaging (ISBI - 2018). In this paper, we report the set-up and results of this challenge that is primarily based on Indian Diabetic Retinopathy Image Dataset (IDRiD). There were three principal sub-challenges: lesion segmentation, disease severity grading, and localization of retinal landmarks and segmentation. These multiple tasks in this challenge allow to test the generalizability of algorithms, and this is what makes it different from existing ones. It received a positive response from the scientific community with 148 submissions from 495 registrations effectively entered in this challenge. This paper outlines the challenge, its organization, the dataset used, evaluation methods and results of top-performing participating solutions. The top-performing approaches utilized a blend of clinical information, data augmentation, and an ensemble of models. These findings have the potential to enable new developments in retinal image analysis and image-based DR screening in particular., (Copyright © 2019 Elsevier B.V. All rights reserved.)
- Published
- 2020
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33. Nickel complexes of ligands derived from (o-hydroxyphenyl) dichalcogenide: delocalised redox states of nickel and o-chalcogenophenolate ligands.
- Author
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Banerjee S, Sheet D, Sarkar S, Halder P, and Paine TK
- Abstract
Two monoanionic nickel complexes Bu4N[Ni(LSeO)2] (1) and Bu4N[Ni(LSO)2] (2) (H2LSeO = 3,5-di-tert-butyl-2-hydroxyselenophenol and H2LSO = 3,5-di-tert-butyl-2-hydroxythiophenol) were synthesised by reductive cleavage of the respective 2,2'-dichalcogenobis(4,6-di-tert-butylphenol) (H2LX-X; X = Se, S) with nickel(ii) salts. The crystal structures of 1 and 2 confirm the reductive X-X bond cleavage with the concomitant formation of the corresponding monoanionic square planar complex, where quinoidal distortions of the aromatic rings are observed. The monoanionic complexes (1 and 2) are paramagnetic (S = 1/2), exhibiting rhombic EPR signals, and the g anisotropies are well correlated with the spin-orbit coupling of chalcogenides. The spectral data indicate that the ligands H2LXO in 1 and 2 are redox non-innocent and stabilise the square planar S = 1/2 nickel complexes with a highly delocalised unpaired electron. DFT calculations further support the delocalised electronic structures of the nickel complexes.
- Published
- 2019
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34. Carbon-Nanotube-Appended PAMAM Dendrimers Bearing Iron(II) α-Keto Acid Complexes: Catalytic Non-Heme Oxygenase Models.
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Sheet D, Bera A, Fu Y, Desmecht A, Riant O, and Hermans S
- Subjects
- Catalysis, Models, Molecular, Oxidation-Reduction, Oxygenases chemistry, Oxygenases metabolism, Sulfides chemistry, Dendrimers chemistry, Ferrous Compounds chemistry, Keto Acids chemistry, Nanotubes, Carbon chemistry
- Abstract
Poly(amidoamine) dendrimers grafted on carbon nanotubes have been appended with iron(II)-α-keto acid (benzoylformate) complex of polypyridyl ligand to design artificial non-heme oxygenase model. This nano-enzyme was applied for selective catalytic oxidation of organic molecules. Although the carbon nanotubes serve as a robust heterogeneous platform, the amine terminals of dendrimers provide catalysts binding sites and the amide bonds provide a necessary second coordination sphere similar to the enzymatic polypeptide chains. Such a hybrid design prevented the deactivation of the primary active sites leading to 8 times faster oxidative decarboxylation rates than those of its homogeneous analogue. An electrophilic iron(IV)-oxo intermediate has been intercepted, which catalyzes the selective oxidation of alcohols to aldehydes and incorporates single oxygen atoms into sulfides and olefins by using aerial oxygen with multiple turnover numbers. The catalyst was consecutively regenerated three times by mild chemical treatment and showed negligible loss of activity., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)
- Published
- 2019
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35. Adversarially Trained Convolutional Neural Networks for Semantic Segmentation of Ischaemic Stroke Lesion using Multisequence Magnetic Resonance Imaging.
- Author
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Sathish R, Rajan R, Vupputuri A, Ghosh N, and Sheet D
- Subjects
- Humans, Magnetic Resonance Imaging, Neural Networks, Computer, Semantics, Brain Ischemia diagnostic imaging, Stroke
- Abstract
Ischaemic stroke is a medical condition caused by occlusion of blood supply to the brain tissue thus forming a lesion. A lesion is zoned into a core associated with irreversible necrosis typically located at the center of the lesion, while reversible hypoxic changes in the outer regions of the lesion are termed as the penumbra. Early estimation of core and penumbra in ischaemic stroke is crucial for timely intervention with thrombolytic therapy to reverse the damage and restore normalcy. Multisequence magnetic resonance imaging (MRI) is commonly employed for clinical diagnosis. However, a sequence singly has not been found to be sufficiently able to differentiate between core and penumbra, while a combination of sequences is required to determine the extent of the damage. The challenge, however, is that with an increase in the number of sequences, it cognitively taxes the clinician to discover symptomatic biomarkers in these images. In this paper, we present a data-driven fully automated method for estimation of core and penumbra in ischaemic lesions using diffusion-weighted imaging (DWI) and perfusion-weighted imaging (PWI) sequence maps of MRI. The method employs recent developments in convolutional neural networks (CNN) for semantic segmentation in medical images. In the absence of availability of a large amount of labeled data, the CNN is trained using an adversarial approach employing cross-entropy as a segmentation loss along with losses aggregated from three discriminators of which two employ relativistic visual Turing test. This method is experimentally validated on the ISLES-2015 dataset through three-fold cross-validation to obtain with an average Dice score of 0.82 and 0.73 for segmentation of penumbra and core respectively.
- Published
- 2019
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36. Anatomical Structure Segmentation in Ultrasound Volumes Using Cross Frame Belief Propagating Iterative Random Walks.
- Author
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China D, Illanes A, Poudel P, Friebe M, Mitra P, and Sheet D
- Subjects
- Abdomen diagnostic imaging, Algorithms, Humans, Phantoms, Imaging, Stochastic Processes, Thyroid Gland diagnostic imaging, Image Processing, Computer-Assisted methods, Models, Statistical, Ultrasonography methods
- Abstract
Ultrasound (US) is widely used as a low-cost alternative to computed tomography or magnetic resonance and primarily for preliminary imaging. Since speckle intensity in US images is inherently stochastic, readers are often challenged in their ability to identify the pathological regions in a volume of a large number of images. This paper introduces a generalized approach for volumetric segmentation of structures in US images and volumes. We employ an iterative random walks (IRW) solver, a random forest learning model, and a gradient vector flow (GVF) based interframe belief propagation technique for achieving cross-frame volumetric segmentation. At the start, a weak estimate of the tissue structure is obtained using estimates of parameters of a statistical mechanics model of US tissue interaction. Ensemble learning of these parameters further using a random forest is used to initialize the segmentation pipeline. IRW is used for correcting the contour in various steps of the algorithm. Subsequently, a GVF-based interframe belief propagation is applied to adjacent frames based on the initialization of contour using information in the current frame to segment the complete volume by frame-wise processing. We have experimentally evaluated our approach using two different datasets. Intravascular ultrasound (IVUS) segmentation was evaluated using 10 pullbacks acquired at 20 MHz and thyroid US segmentation is evaluated on 16 volumes acquired at [Formula: see text] MHz. Our approach obtains a Jaccard score of [Formula: see text] for IVUS segmentation and [Formula: see text] for thyroid segmentation while processing each frame in [Formula: see text] for the IVUS and in [Formula: see text] for thyroid segmentation without the need of any computing accelerators such as GPUs.
- Published
- 2019
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37. Oxidizing Ability of a Dioxygen-Activating Nonheme Iron(II)-Benzilate Complex Immobilized on Gold Nanoparticles.
- Author
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Sheet D, Bera A, Jana RD, and Paine TK
- Abstract
An iron(II)-benzilate complex [(TPASH)Fe
II (benzilate)]ClO4 @C8 Au (2) (TPASH = 11-((6-((bis(pyridin-2-ylmethyl)amino)methyl)pyridin-2-yl)methoxy)undecane-1-thiol) immobilized on octanethiol stabilized gold nanoparticles (C8 Au) of core diameter less than 5 nm has been prepared to evaluate its reactivity toward O2 -dependent oxidations compared to a nonimmobilized complex [(TPA-O-Allyl)FeII (benzilate)]ClO4 (1a) (TPA-O-Allyl = N-((6-(allyloxymethyl)pyridin-2-yl)methyl)(pyridin-2-yl)- N-(pyridin-2-ylmethyl)methanamine). X-ray crystal structure of the nonimmobilized complex 1a reveals a six-coordinate iron(II) center in which the TPA-O-Allyl acts as a pentadentate ligand and the benzilate anion binds in monodentate fashion. Both the complexes (1a and 2) react with dioxygen under ambient conditions to form benzophenone as the sole product through decarboxylation of the coordinated benzilate. Interception studies reveal that a nucleophilic iron-oxygen intermediate is formed in the decarboxylation reaction. The oxidants from both the complexes are able to carry out oxo atom transfer reactions. The immobilized complex 2 not only performs faster decarboxylation but also exhibits enhanced reactivity in oxo atom transfer to sulfides. Importantly, the immobilized complex 2, unlike 1a, displays catalytic turnovers in sulfide oxidation. However, the complexes are not efficient to carry out cis-dihydroxylation of alkenes. Although the immobilized complex yields a slightly higher amount of cis-diol from 1-octene, restricted access of dioxygen and substrates at the coordinatively saturated metal centers of the complexes likely makes the resulting iron-oxygen species less active in oxygen atom transfer to alkenes. The results implicate that surface immobilized nonheme iron complexes containing accessible coordination sites would exhibit better reactivity in O2 -dependent oxygenation reactions.- Published
- 2019
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38. Covalent Grafting of BPin functions on Carbon Nanotubes and Chan-Lam-Evans Post-Functionalization.
- Author
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Desmecht A, Sheet D, Poleunis C, Hermans S, and Riant O
- Abstract
The chemical functionalization of carbon nanotubes is often a prerequisite prior to their use in various applications. The covalent grafting of 4,4,5,5-tetramethyl-1,3,2-dioxaborolane (BPin) functional groups directly on the surface of multi- and single-walled carbon nanotubes, activated by nucleophilic addition of nBuLi, was carried out. Thermogravimetric analysis (TGA) coupled with mass spectrometry, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ions mass spectrometry (ToF-SIMS) confirmed the efficiency of this methodology and proved the integrity and covalent grafting of the BPin functional groups. These groups were further reacted with various nucleophiles in the presence of a copper(II) source in the conditions of the aerobic Chan-Lam-Evans coupling. The resulting materials were characterized by TGA, XPS and ToF-SIMS. This route is efficient, reliable and among the scarce reactions that enable the direct grafting of heteroatoms at carbonaceous material surfaces., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)
- Published
- 2019
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39. Evaluation of Commonly Used Algorithms for Thyroid Ultrasound Images Segmentation and Improvement Using Machine Learning Approaches.
- Author
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Poudel P, Illanes A, Sheet D, and Friebe M
- Subjects
- Automation, Decision Trees, Diagnosis, Computer-Assisted, Humans, Imaging, Three-Dimensional, Neural Networks, Computer, Reproducibility of Results, Software, Thyroid Gland diagnostic imaging, Algorithms, Image Processing, Computer-Assisted methods, Machine Learning, Thyroid Neoplasms diagnostic imaging, Ultrasonography
- Abstract
The thyroid is one of the largest endocrine glands in the human body, which is involved in several body mechanisms like controlling protein synthesis and the body's sensitivity to other hormones and use of energy sources. Hence, it is of prime importance to track the shape and size of thyroid over time in order to evaluate its state. Thyroid segmentation and volume computation are important tools that can be used for thyroid state tracking assessment. Most of the proposed approaches are not automatic and require long time to correctly segment the thyroid. In this work, we compare three different nonautomatic segmentation algorithms (i.e., active contours without edges, graph cut, and pixel-based classifier) in freehand three-dimensional ultrasound imaging in terms of accuracy, robustness, ease of use, level of human interaction required, and computation time. We figured out that these methods lack automation and machine intelligence and are not highly accurate. Hence, we implemented two machine learning approaches (i.e., random forest and convolutional neural network) to improve the accuracy of segmentation as well as provide automation. This comparative study intends to discuss and analyse the advantages and disadvantages of different algorithms. In the last step, the volume of the thyroid is computed using the segmentation results, and the performance analysis of all the algorithms is carried out by comparing the segmentation results with the ground truth.
- Published
- 2018
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40. Aliphatic C-H Bond Halogenation by Iron(II)-α-Keto Acid Complexes and O 2 : Functional Mimicking of Nonheme Iron Halogenases.
- Author
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Jana RD, Sheet D, Chatterjee S, and Paine TK
- Subjects
- Alkanes chemistry, Halogenation, Hydroxylation, Molecular Structure, Oxidation-Reduction, Oxidoreductases chemistry, Biomimetic Materials chemistry, Coordination Complexes chemistry, Hydrocarbons, Chlorinated chemical synthesis, Iron Compounds chemistry, Keto Acids chemistry, Oxygen chemistry
- Abstract
α-Ketoglutarate-dependent nonheme halogenases catalyze the halogenation of aliphatic C-H bonds in the biosynthesis pathway of many natural products. An iron(IV)-oxo-halo species has been established as the active oxidant in the halogenation reactions. With an objective to emulate the function of the nonheme halogenases, two iron(II)-α-keto acid complexes, [(phdpa)Fe(BF)Cl] (1) and [(1,4-tpbd)Fe
2 (BF)2 Cl2 ] (2) (where phdpa = N,N-bis(2-pyridylmethyl)aniline, 1,4-tpbd = N,N, N',N'-tetrakis(2-pyridylmethyl)benzene-1,4-diamine, and BF = benzoylformate), have been prepared. The iron complexes are capable of carrying out the oxidative halogenation of aliphatic C-H bonds using O2 as the terminal oxidant. Although the complexes are not selective toward C-H bond halogenation, they are the only examples of nonheme iron(II)-α-keto acid complexes mimicking the activity of nonheme halogenases. The dinuclear complex (2) exhibits enhanced reactivity toward C-H bond halogenation/hydroxylation.- Published
- 2018
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41. A Deep Convolutional Neural Network Based Classification Of Multi-Class Motor Imagery With Improved Generalization.
- Author
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Kar A, Bera S, Karri SPK, Ghosh S, Mahadevappa M, and Sheet D
- Subjects
- Algorithms, Electroencephalography, Imagery, Psychotherapy, Neural Networks, Computer, Brain-Computer Interfaces
- Abstract
Motor imagery (MI) based brain-computer interface (BCI) plays a crucial role in various scenarios ranging from post-traumatic rehabilitation to control prosthetics. Computer-aided interpretation of MI has augmented prior mentioned scenarios since decades but failed to address interpersonal variability. Such variability further escalates in case of multi-class MI, which is currently a common practice. The failures due to interpersonal variability can be attributed to handcrafted features as they failed to extract more generalized features. The proposed approach employs convolution neural network (CNN) based model with both filtering (through axis shuffling) and feature extraction to avail end-to-end training. Axis shuffling is performed adopted in initial blocks of the model for 1D preprocessing and reduce the parameters required. Such practice has avoided the overfitting which resulted in an improved generalized model. Publicly available BCI Competition-IV 2a dataset is considered to evaluate the proposed model. The proposed model has demonstrated the capability to identify subject-specific frequency band with an average and highest accuracy of 70.5% and S3.6% respectively. Proposed CNN model can classify in real time without relying on accelerated computing device like GPU.
- Published
- 2018
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42. ReLayNet: retinal layer and fluid segmentation of macular optical coherence tomography using fully convolutional networks.
- Author
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Roy AG, Conjeti S, Karri SPK, Sheet D, Katouzian A, Wachinger C, and Navab N
- Abstract
Optical coherence tomography (OCT) is used for non-invasive diagnosis of diabetic macular edema assessing the retinal layers. In this paper, we propose a new fully convolutional deep architecture, termed ReLayNet, for end-to-end segmentation of retinal layers and fluid masses in eye OCT scans. ReLayNet uses a contracting path of convolutional blocks (encoders) to learn a hierarchy of contextual features, followed by an expansive path of convolutional blocks (decoders) for semantic segmentation. ReLayNet is trained to optimize a joint loss function comprising of weighted logistic regression and Dice overlap loss. The framework is validated on a publicly available benchmark dataset with comparisons against five state-of-the-art segmentation methods including two deep learning based approaches to substantiate its effectiveness.
- Published
- 2017
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43. Toward a Comprehensive Cure: Digital information and communication technology is helping to meet health care challenges in India.
- Author
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Sheet D
- Subjects
- Cell Phone, Communication, Humans, India, Tuberculosis therapy, Comprehensive Health Care, Telemedicine
- Abstract
How would you provide effective and affordable health care in a country of more than 1.25 billion where there are only 0.7 physicians for every 1,000 people [1]? The Revised National Tuberculosis Control Program (RNTCP) and the Karnataka Internet-Assisted Diagnosis of Retinopathy of Prematurity (KIDROP) service are two notable efforts designed to deliver care across India, in both urban and rural areas and from the country?s flat plains to its rugged mountainous and desert regions.
- Published
- 2016
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44. Learning of speckle statistics for in vivo and noninvasive characterization of cutaneous wound regions using laser speckle contrast imaging.
- Author
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Basak K, Dey G, Mahadevappa M, Mandal M, Sheet D, and Dutta PK
- Subjects
- Animals, Area Under Curve, Blood Flow Velocity, Data Interpretation, Statistical, Disease Models, Animal, Immunohistochemistry, Laser-Doppler Flowmetry statistics & numerical data, Male, Mice, Perfusion Imaging statistics & numerical data, Predictive Value of Tests, ROC Curve, Regional Blood Flow, Reproducibility of Results, Sarcoma 180 pathology, Skin pathology, Time Factors, Wound Healing, Image Interpretation, Computer-Assisted methods, Laser-Doppler Flowmetry methods, Microcirculation, Perfusion Imaging methods, Sarcoma 180 blood supply, Sarcoma 180 diagnostic imaging, Skin blood supply, Supervised Machine Learning
- Abstract
Laser speckle contrast imaging (LSCI) provides a noninvasive and cost effective solution for in vivo monitoring of blood flow. So far, most of the researches consider changes in speckle pattern (i.e. correlation time of speckle intensity fluctuation), account for relative change in blood flow during abnormal conditions. This paper introduces an application of LSCI for monitoring wound progression and characterization of cutaneous wound regions on mice model. Speckle images are captured on a tumor wound region at mice leg in periodic interval. Initially, raw speckle images are converted to their corresponding contrast images. Functional characterization begins with first segmenting the affected area using k-means clustering, taking wavelet energies in a local region as feature set. In the next stage, different regions in wound bed are clustered based on progressive and non-progressive nature of tissue properties. Changes in contrast due to heterogeneity in tissue structure and functionality are modeled using LSCI speckle statistics. Final characterization is achieved through supervised learning of these speckle statistics using support vector machine. On cross evaluation with mice model experiment, the proposed approach classifies the progressive and non-progressive wound regions with an average sensitivity of 96.18%, 97.62% and average specificity of 97.24%, 96.42% respectively. The clinical information yield with this approach is validated with the conventional immunohistochemistry result of wound to justify the ability of LSCI for in vivo, noninvasive and periodic assessment of wounds., (Copyright © 2016 Elsevier Inc. All rights reserved.)
- Published
- 2016
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45. Aerobic alcohol oxidation and oxygen atom transfer reactions catalyzed by a nonheme iron(ii)-α-keto acid complex.
- Author
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Sheet D and Paine TK
- Abstract
α-Ketoglutarate-dependent enzymes catalyze many important biological oxidation/oxygenation reactions. Iron(iv)-oxo intermediates have been established as key oxidants in these oxidation reactions. While most reported model iron(ii)-α-keto acid complexes exhibit stoichiometric reactivity, selective oxidation of substrates with dioxygen catalyzed by biomimetic iron(ii)-α-keto acid complexes remains unexplored. In this direction, we have investigated the ability of an iron(ii) complex [(Tp
Ph,Me )FeII (BF)] ( 1 ) (TpPh,Me = hydrotris(3-phenyl-5-methylpyrazolyl)borate and BF = monoanionic benzoylformate) to catalyze the aerobic oxidation of organic substrates. An iron-oxo oxidant, intercepted in the reaction of 1 with O2 , selectively oxidizes sulfides to sulfoxides, alkenes to epoxides, and alcohols to the corresponding carbonyl compounds. The oxidant from 1 is able to hydroxylate the benzylic carbon of phenylacetic acid to afford mandelic acid with the incorporation of one oxygen atom from O2 into the product. The iron(ii)-benzoylformate complex oxidatively converts phenoxyacetic acids to the corresponding phenols, thereby mimicking the function of iron(ii)-α-ketoglutarate-dependent 2,4-dichlorophenoxyacetate dioxygenase (TfdA). Furthermore, complex 1 exhibits catalytic aerobic oxidation of alcohols and oxygen atom transfer reactions with multiple turnovers.- Published
- 2016
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46. Supervised domain adaptation of decision forests: Transfer of models trained in vitro for in vivo intravascular ultrasound tissue characterization.
- Author
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Conjeti S, Katouzian A, Roy AG, Peter L, Sheet D, Carlier S, Laine A, and Navab N
- Subjects
- Humans, Reproducibility of Results, Sensitivity and Specificity, Coronary Circulation, Heart diagnostic imaging, Image Processing, Computer-Assisted methods, Supervised Machine Learning, Ultrasonography methods
- Abstract
In this paper, we propose a supervised domain adaptation (DA) framework for adapting decision forests in the presence of distribution shift between training (source) and testing (target) domains, given few labeled examples. We introduce a novel method for DA through an error-correcting hierarchical transfer relaxation scheme with domain alignment, feature normalization, and leaf posterior reweighting to correct for the distribution shift between the domains. For the first time we apply DA to the challenging problem of extending in vitro trained forests (source domain) for in vivo applications (target domain). The proof-of-concept is provided for in vivo characterization of atherosclerotic tissues using intravascular ultrasound signals, where presence of flowing blood is a source of distribution shift between the two domains. This potentially leads to misclassification upon direct deployment of in vitro trained classifier, thus motivating the need for DA as obtaining reliable in vivo training labels is often challenging if not infeasible. Exhaustive validations and parameter sensitivity analysis substantiate the reliability of the proposed DA framework and demonstrates improved tissue characterization performance for scenarios where adaptation is conducted in presence of only a few examples. The proposed method can thus be leveraged to reduce annotation costs and improve computational efficiency over conventional retraining approaches., (Copyright © 2016 Elsevier B.V. All rights reserved.)
- Published
- 2016
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47. Deep neural ensemble for retinal vessel segmentation in fundus images towards achieving label-free angiography.
- Author
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Lahiri A, Roy AG, Sheet D, and Biswas PK
- Subjects
- Algorithms, Angiography methods, Diabetic Retinopathy diagnostic imaging, Diagnosis, Computer-Assisted, Fundus Oculi, Humans, Retinal Vessels pathology, Image Processing, Computer-Assisted methods, Retinal Diseases diagnostic imaging, Retinal Vessels diagnostic imaging
- Abstract
Automated segmentation of retinal blood vessels in label-free fundus images entails a pivotal role in computed aided diagnosis of ophthalmic pathologies, viz., diabetic retinopathy, hypertensive disorders and cardiovascular diseases. The challenge remains active in medical image analysis research due to varied distribution of blood vessels, which manifest variations in their dimensions of physical appearance against a noisy background. In this paper we formulate the segmentation challenge as a classification task. Specifically, we employ unsupervised hierarchical feature learning using ensemble of two level of sparsely trained denoised stacked autoencoder. First level training with bootstrap samples ensures decoupling and second level ensemble formed by different network architectures ensures architectural revision. We show that ensemble training of auto-encoders fosters diversity in learning dictionary of visual kernels for vessel segmentation. SoftMax classifier is used for fine tuning each member autoencoder and multiple strategies are explored for 2-level fusion of ensemble members. On DRIVE dataset, we achieve maximum average accuracy of 95.33% with an impressively low standard deviation of 0.003 and Kappa agreement coefficient of 0.708. Comparison with other major algorithms substantiates the high efficacy of our model.
- Published
- 2016
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48. Lumen Segmentation in Intravascular Optical Coherence Tomography Using Backscattering Tracked and Initialized Random Walks.
- Author
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Guha Roy A, Conjeti S, Carlier SG, Dutta PK, Kastrati A, Laine AF, Navab N, Katouzian A, and Sheet D
- Subjects
- Humans, Scattering, Radiation, Coronary Vessels diagnostic imaging, Image Processing, Computer-Assisted methods, Tomography, Optical Coherence methods, Ultrasonography, Interventional methods
- Abstract
Intravascular imaging using ultrasound or optical coherence tomography (OCT) is predominantly used to adjunct clinical information in interventional cardiology. OCT provides high-resolution images for detailed investigation of atherosclerosis-induced thickening of the lumen wall resulting in arterial blockage and triggering acute coronary events. However, the stochastic uncertainty of speckles limits effective visual investigation over large volume of pullback data, and clinicians are challenged by their inability to investigate subtle variations in the lumen topology associated with plaque vulnerability and onset of necrosis. This paper presents a lumen segmentation method using OCT imaging physics-based graph representation of signals and random walks image segmentation approaches. The edge weights in the graph are assigned incorporating OCT signal attenuation physics models. Optical backscattering maxima is tracked along each A-scan of OCT and is subsequently refined using global graylevel statistics and used for initializing seeds for the random walks image segmentation. Accuracy of lumen versus tunica segmentation has been measured on 15 in vitro and 6 in vivo pullbacks, each with 150-200 frames using 1) Cohen's kappa coefficient (0.9786 ±0.0061) measured with respect to cardiologist's annotation and 2) divergence of histogram of the segments computed with Kullback-Leibler (5.17 ±2.39) and Bhattacharya measures (0.56 ±0.28). High segmentation accuracy and consistency substantiates the characteristics of this method to reliably segment lumen across pullbacks in the presence of vulnerability cues and necrotic pool and has a deterministic finite time-complexity. This paper in general also illustrates the development of methods and framework for tissue classification and segmentation incorporating cues of tissue-energy interaction physics in imaging.
- Published
- 2016
- Full Text
- View/download PDF
49. Deep neural network and random forest hybrid architecture for learning to detect retinal vessels in fundus images.
- Author
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Maji D, Santara A, Ghosh S, Sheet D, and Mitra P
- Subjects
- Fundus Oculi, Humans, Neural Networks, Computer, Retina, Retinal Vessels
- Abstract
Vision impairment due to pathological damage of the retina can largely be prevented through periodic screening using fundus color imaging. However the challenge with large-scale screening is the inability to exhaustively detect fine blood vessels crucial to disease diagnosis. In this work we present a computational imaging framework using deep and ensemble learning based hybrid architecture for reliable detection of blood vessels in fundus color images. A deep neural network (DNN) is used for unsupervised learning of vesselness dictionaries using sparse trained denoising auto-encoders (DAE), followed by supervised learning of the DNN response using a random forest for detecting vessels in color fundus images. In experimental evaluation with the DRIVE database, we achieve the objective of vessel detection with max. avg. accuracy of 0.9327 and area under ROC curve of 0.9195.
- Published
- 2015
- Full Text
- View/download PDF
50. Modulating prime molecular expressions and in vitro wound healing rate in keratinocyte (HaCaT) population under characteristic honey dilutions.
- Author
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Chaudhary A, Bag S, Mandal M, Krishna Karri SP, Barui A, Rajput M, Banerjee P, Sheet D, and Chatterjee J
- Subjects
- Antioxidants pharmacology, Cadherins genetics, Cell Line, Cell Movement drug effects, Cell Proliferation drug effects, Cell Survival drug effects, Cell Survival genetics, Down-Regulation drug effects, Epithelial Cells drug effects, Gene Expression genetics, Honey, Humans, Membrane Proteins genetics, N-Acetylglucosaminyltransferases genetics, RNA, Messenger genetics, Up-Regulation drug effects, Wound Healing genetics, beta Catenin genetics, Biological Factors pharmacology, Gene Expression drug effects, Keratinocytes drug effects, Wound Healing drug effects
- Abstract
Ethnopharmacology Relevance: In traditional medicines honey is known for healing efficacy and vividly used as "Anupan" in Ayurvedic medicines appreciating roles in dilutions. Validating efficacy of physico-chemically characterized honey in dilutions, studies on in vitro wound healing and attainment of cellular confluence epithelial cells including expressions of cardinal genes is crucial. To evaluate effects of characterized honey in varied dilutions on cellular viability, in vitro wound healing and modulation of prime epithelial gene expressions., Materials and Methods: Six Indian honey-samples from different sources were physico-chemically characterized and optimal one was explored in dilutions (v/v%) through in vitro studies on human epithelial (HaCaT) cells for viability, wound healing and expressions of genes p63, E-cadherin, β-catenin, GnT-III and GnT-V., Results: Studied honey samples (i.e. A-F) depicted range of pH (2-4), water (12.48-23.95), electrical conductivity (2.57-14.34), carbohydrate (68.73-98.65), protein (.316-5.36) and antioxidant potential. Though sample A and F showed physico-chemical proximity, but overall bio-impact of the earlier was better, thus studied in 8-.1% (v/v) dilution range. Four dilutions (.01, .04, .1, .25 v/v%) augmented cellular viability but in vitro wound healing was fastest (p<.05) under .1%. Such efficacy was further documented for p63 up-regulation by immunocytochemistry and mRNA studies. The E-cadherin and β-catenin mRNA-expressions were also up-regulated and their proteins were predominantly cytoplasmic. E-cadherin up-regulation was corroborative with down-regulation and up-regulation of GnT-III and GnT-V respectively., Conclusion: Present study illustrated efficacy of particular honey dilution (.1%) with characteristic free radical scavenging activity in facilitating cell proliferation and attainment of confluence towards faster wound healing and modulation of cardinal epithelial genes (viz. p63, E-cadherin, β-catenin, Gnt-III and V)., (Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.)
- Published
- 2015
- Full Text
- View/download PDF
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