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Challenges of Medical Text and Image Processing: Machine Learning Approaches

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Machine Learning for Health Informatics

Part of the book series: Lecture Notes in Computer Science ((LNAI,volume 9605))

Abstract

The generalized adoption of Electronic Medical Records (EMR) together with the need to give the patient the appropriate treatment at the appropriate moment at the appropriate cost is demanding solutions to analyze the information on the EMR automatically. However most of the information on the EMR is non-structured: texts and images. Extracting knowledge from this data requires methods for structuring this information. Despite the efforts made in Natural Language Processing (NLP) even in the biomedical domain and in image processing, medical big data has still to undertake several challenges. The ungrammatical structure of clinical notes, abbreviations used and evolving terms have to be tackled in any Name Entity Recognition process. Moreover abbreviations, acronyms and terms are very much dependant on the language and the specific service. On the other hand, in the area of medical images, one of the main challenges is the development of new algorithms and methodologies that can help the physician take full advantage of the information contained in all these images. However, the large number of imaging modalities used today for diagnosis hinders the availability of general procedures as machine learning is, once again, a good approach for addressing this challenge. In this chapter, which concentrates on the problem of name entity recognition, we review previous approaches and look at future works. We also review the machine leaning approaches for image segmentation and annotation.

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Notes

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    http://webeye.ophth.uiowa.edu/ROC/.

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    http://www.miccai.org.

References

  1. Huang, T.S., Dagli, C.K., Rajaram, S., Chang, E.Y., Mandel, M., Poliner, G.E., Ellis, D.P., et al.: Active learning for interactive multimedia retrieval. Proc. IEEE 96(4), 648–667 (2008)

    Article  Google Scholar 

  2. Wei, C.H., Chen, S.Y.: Annotation of medical images. In: Intelligent Multimedia Databases and Information Retrieval: Advancing Applications and Technologies, pp. 74–90 (2012)

    Google Scholar 

  3. Murphy, K.P.: Machine Learning: A Probabilistic Perspective. John Wiley & Sons Ltd., Chichester (2012)

    MATH  Google Scholar 

  4. Toutanova, K., Klein, D., C.M., Singer, Y.: Feature-rich part-of-speech tagging with a cyclic dependency network. In: Proceedings of HLT-NAACL (2003)

    Google Scholar 

  5. Holzinger, A., Geierhofer, R., Modritscher, F., Tatzl, R.: Semantic information in medical information systems: utilization of text mining techniques to analyze medical diagnoses. J. Univ. Comput. Sci. 14(22), 3781–3795 (2008)

    Google Scholar 

  6. Kavuluru, R., Rios, A., Lu, Y.: An empirical evaluation of supervised learning approaches in assigning diagnosis codes to electronic medical records. Artif. Intell. Med. 65(2), 155–166 (2015). Intelligent healthcare informatics in big data era

    Article  Google Scholar 

  7. Tsuruoka, Y., McNaught, J., Tsujii, J., Ananiadou, S.: Learning string similarity measures for gene/protein name dictionary look-up using logistic regression. Bioinformatics 23(20), 2768–2774 (2007)

    Article  Google Scholar 

  8. http://www.cs.nyu.edu/cs/projects/lsp/. Accessed 5 Dec 2015

  9. http://www.medlingmap.org/taxonomy/term/80. Accesed 5 Dec 2015

  10. Savova, G.K., Masanz, J.J., Ogren, P.V., Zheng, J., Sohn, S., Kipper-Schuler, K.C., Chute, C.G.: Mayo clinical text analysis and knowledge extraction system (cTAKES): architecture, component evaluation and applications. J. Am. Med. Inf. Assoc. 17(5), 507–513 (2010)

    Article  Google Scholar 

  11. Goryachev, S., Sordo, M., Zeng, Q.T.: A suite of natural language processing tools developed for the I2B2 project, Boston, Massachusetts, Decision Systems Group. Brigham and Women’s Hospital, Harvard Medical School (2006)

    Google Scholar 

  12. Joshi, M., Pakhomov, S., Pederson, T., Chute, C.: A comparative study of supervised learning as applied to acronym expansion in clinical reports. In: AMIA Annual Symposium Proceedings, pp. 399–403 (2006)

    Google Scholar 

  13. Pakhomov, S., Pedersen, T., Chute, C.G.: Abbreviation and acronym disambiguation in clinical discourse. In: AMIA Annual Symposium Proceedings, pp. 589–593 (2005)

    Google Scholar 

  14. Toutanova, K., Manning, C.D.: Enriching the knowledge sources used in a maximum entropy part-of-speech tagger. In: Joint SIGDAT Conference on Empirical Methods in Natural Language Processing and Very Large Corpora (EMNLP/VLC-2000), Hong Kong (2000)

    Google Scholar 

  15. Smith, L., Rindflesch, T., Wilbur, W.J.: MedPost: a part-of-speech tagger for bioMedical text. Bioinformatics (Oxford, England) 20(14), 2320–2321 (2004)

    Article  Google Scholar 

  16. Wermter, J., Hahn, U.: Really, is medical sublanguage that different? Experimental counter-evidence from tagging medical and newspaper corpora. In: 11th World Congress on Medical Informatics (MEDINFO) (2004)

    Google Scholar 

  17. Pakhomov, S.V., Coden, A., Chute, C.G.: Developing a corpus of clinical notes manually annotated for part-of-speech. Int. J. Med. Inf. 75(6), 418–429 (2006)

    Article  Google Scholar 

  18. http://www-nlp.stanford.edu/links/statnlp.html. Acessed 5 Dec 2015

  19. Holzinger, A., Schantl, J., Schroettner, M., Seifert, C., Verspoor, K.: Biomedical text mining: state-of-the-art, open problems and future challenges. In: Holzinger, A., Jurisica, I. (eds.) Interactive Knowledge Discovery and Data Mining in Biomedical Informatics. LNCS, vol. 8401, pp. 271–300. Springer, Heidelberg (2014)

    Google Scholar 

  20. Poibeau, T., Kosseim, L.: Proper name extraction from non-journalistic texts. In: Daelemans, W., Sima’an, K., Veenstra, J., Zavrel, J., (eds.) CLIN, vol. 37 of Language and Computers - Studies in Practical Linguistics, Rodopi, pp. 144–157 (2000)

    Google Scholar 

  21. Demner-Fushman, D., Chapman, W.W., McDonald, C.J.: What can natural language processing do for clinical decision support? J. Biomed. Inf. 42(5), 760–772 (2009)

    Article  Google Scholar 

  22. Ananiadou, S., Mcnaught, J.: Text Mining for Biology and Biomedicine. Artech House Inc., Norwood (2005)

    Google Scholar 

  23. Korkontzelos, I., Piliouras, D., Dowsey, A.W., Ananiadou, S.: Boosting drug named entity recognition using an aggregate classifier. Artif. Intell. Med. 65(2), 145–153 (2015). Intelligent healthcare informatics in big data era

    Article  Google Scholar 

  24. Dagan, I., Engelson, S.P.: Committee-based sampling for training probabilistic classifiers. In: Proceedings of the Twelfth International Conference on Machine Learning, pp. 150–157. Morgan Kaufmann (1995)

    Google Scholar 

  25. Tomanek, K., Wermter, J., Hahn, U.: An approach to text corpus construction which cuts annotation costs and maintains reusability of annotated data. In: Proceedings of EMNLP/CoNLL07, pp. 486–495 (2007)

    Google Scholar 

  26. Bodenreider, O.: The unified medical language system (UMLS): integrating biomedical terminology. Nucleic Acids Res. 32, D267–D270 (2004)

    Article  Google Scholar 

  27. Johnson, S.B.: A semantic lexicon for medical language processing. J. Am. Med. Inf. Assoc. 6(3), 205–218 (1999)

    Article  Google Scholar 

  28. Mougin, F., Burgun, A., Bodenreider, O.: Using wordnet to improve the mapping of data elements to UMLS for data sources integration. In: AMIA Annual Symposium Proceedings, vol. 2006, p. 574. American Medical Informatics Association (2006)

    Google Scholar 

  29. Nadeau, D., Sekine, S.: A survey of named entity recognition and classification. Lingvisticae Investigationes 30(1), 3–26 (2007)

    Article  Google Scholar 

  30. Bikel, D.M., Miller, S., Schwartz, R., Weischedel, R.: Nymble: a high-performance learning name-finder. In: Proceedings of the Fifth Conference on Applied Natural Language Processing, pp. 194–201. Association for Computational Linguistics (1997)

    Google Scholar 

  31. Satoshi Sekine, N.: Description of the Japanese NE system used for MET-2. In: Proceedings of MUC-7, Verginia, USA, pp. 1314–1319 (1998)

    Google Scholar 

  32. Borthwick, A., Sterling, J., Agichtein, E., Grishman, R.: NYU: description of the MENE named entity system as used in MUC-7. In: Proceedings of the Seventh Message Understanding Conference (MUC-7). Citeseer (1998)

    Google Scholar 

  33. Asahara, M., Matsumoto, Y.: Japanese named entity extraction with redundant morphological analysis. In: Proceedings of the 2003 Conference of the North American Chapter of the Association for Computational Linguistics on Human Language Technology, vol. 1, pp. 8–15. Association for Computational Linguistics (2003)

    Google Scholar 

  34. McCallum, A., Li, W.: Early results for named entity recognition with conditional random fields, feature induction and web-enhanced lexicons. In: Proceedings of the Seventh Conference on Natural Language Learning at HLT-NAACL 2003 (CONLL 2003), Stroudsburg, PA, USA, vol. 4, pp. 188–191. Association for Computational Linguistics (2003)

    Google Scholar 

  35. Nadeau, D., Turney, P.D., Matwin, S.: Unsupervised named-entity recognition: generating gazetteers and resolving ambiguity. In: Lamontagne, L., Marchand, M. (eds.) AI 2006. LNCS (LNAI), vol. 4013, pp. 266–277. Springer, Heidelberg (2006). doi:10.1007/11766247_23

    Chapter  Google Scholar 

  36. http://nlp.stanford.edu/software/CRF-NER.shtml. Accessed 5 Dec 2015

  37. Sang, E.F.T.K., De Meulder, F.: Introduction to the CoNLL-2003 shared task: language-independent named entity recognition. In: Proceedings of the Seventh Conference on Natural Language Learning at HLT-NAACL 2003, vol. 4, pp. 142–147. Association for Computational Linguistics (2003)

    Google Scholar 

  38. Florian, R., Ittycheriah, A., Jing, H., Zhang, T.: Named entity recognition through classifier combination. In: Proceedings of CoNLL-2003, pp. 168–171 (2003)

    Google Scholar 

  39. Krallinger, M., Leitner, F., Rabal, O., Vazquez, M., Oyarzabal, J., Valencia, A.: Overview of the chemical compound and drug name recognition (CHEMDNER) task. In: BioCreative Challenge Evaluation Workshop, vol. 2, p. 2 (2013)

    Google Scholar 

  40. Meystre, S., Savova, G., Kipper-Schuler, K., Hurdle, J.: Extracting information from textual documents in the electronic health record: a review of recent research. Yearb. Med. Inf. 35, 128–144 (2008)

    Google Scholar 

  41. Ananiadou, S., Friedman, C., Tsujii, J.: Introduction: named entity recognition in biomedicine. J. Biomed. Inf. 37(6), 393–395 (2004)

    Article  Google Scholar 

  42. Ohta, T., Tateisi, Y., Kim, J.D.: The GENIA corpus: an annotated research abstract corpus in molecular biology domain. In: Proceedings of the Second International Conference on Human Language Technology Research (HLT 2002), San Francisco, CA, USA, pp. 82–86. Morgan Kaufmann Publishers Inc. (2002)

    Google Scholar 

  43. Ogren, P.V., Savova, G.K., Chute, C.G.: Constructing evaluation corpora for automated clinical named entity recognition. In: LREC. European Language Resources Association (2008)

    Google Scholar 

  44. Roberts, A., Gaizauskas, R.J., Hepple, M., Demetriou, G., Guo, Y., Roberts, I., Setzer, A.: Building a semantically annotated corpus of clinical texts. J. Biomed. Inf. 42(5), 950–966 (2009)

    Article  Google Scholar 

  45. Li, D., Kipper-Schuler, K., Savova, G.: Conditional random fields and support vector machines for disorder named entity recognition in clinical texts. In: Proceedings of the HLT Workshop on Current Trends in Biomedical Natural Language Processing, Ohio, USA (2008)

    Google Scholar 

  46. Yang, L., Zhou, Y.: Exploring feature sets for two-phase biomedical named entity recognition using semi-CRFs. Knowl. Inf. Syst. 40(2), 439–453 (2014)

    Article  Google Scholar 

  47. Wang, X., Yang, C., Guan, R.: A comparative study for biomedical named entity recognition. Int. J. Mach. Learn. Cybern. 1–10 (2015). Springer

    Google Scholar 

  48. Tanabe, L., Xie, N., Thom, L.H., Matten, W., Wilbur, W.J.: GENETAG: a tagged corpus for gene/protein named entity recognition. BMC Bioinf. 6(Suppl 1), 1 (2005)

    Article  Google Scholar 

  49. Tang, Z., Jiang, L., Yang, L., Li, K., Li, K.: CRFs based parallel biomedical named entity recognition algorithm employing mapreduce framework. Cluster Comput. 18(2), 493–505 (2015)

    Article  Google Scholar 

  50. He, L., Yang, Z., Lin, H., Li, Y.: Drug name recognition in biomedical texts: a machine-learning-based method. Drug Disc. Today 19(5), 610–617 (2014)

    Article  Google Scholar 

  51. Gobbel, G.T., Reeves, R., Jayaramaraja, S., Giuse, D., Speroff, T., Brown, S.H., Elkin, P.L., Matheny, M.E.: Development and evaluation of RapTAT: a machine learning system for concept mapping of phrases from medical narratives. J. Biomed. Inf. 48, 54–65 (2014)

    Article  Google Scholar 

  52. Kim, J.D., Ohta, T., Tateisi, Y., Ichi Tsujii, J.: GENIA corpus - a semantically annotated corpus for bio-textmining. ISMB (Suppl. Bioinf.) 19, 180–182 (2003)

    Google Scholar 

  53. Seth, K., Bies, A., Liberman, M., Mandel, M., Mcdonald, R., Palmer, M., Schein, A.: Integrated annotation for biomedical information extraction. In: Proceedings of the BioLINK 2004 (2004)

    Google Scholar 

  54. Holzinger, A.: Interactive machine learning for health informatics: when do we need the human-in-the-loop? Brain Inf. 3(2), 119–131 (2016)

    Article  Google Scholar 

  55. Yimam, S.M., Biemann, C., Majnaric, L., Šabanović, Š., Holzinger, A.: An adaptive annotation approach for biomedical entity and relation recognition. Brain Inf. 3(3), 1–12 (2016). Springer

    Google Scholar 

  56. Girardi, D., Küng, J., Kleiser, R., Sonnberger, M., Csillag, D., Trenkler, J., Holzinger, A.: Interactive knowledge discovery with the doctor-in-the-loop: a practical example of cerebral aneurysms research. Brain Inf. 3(3), 1–11 (2016). Springer

    Google Scholar 

  57. Holzinger, A., Plass, M., Holzinger, K., Crişan, G.C., Pintea, C.-M., Palade, V.: Towards interactive machine learning (iML): applying ant colony algorithms to solve the traveling salesman problem with the human-in-the-loop approach. In: Buccafurri, F., Holzinger, A., Kieseberg, P., Tjoa, A.M., Weippl, E. (eds.) CD-ARES 2016. LNCS, vol. 9817, pp. 81–95. Springer, Heidelberg (2016). doi:10.1007/978-3-319-45507-5_6

    Chapter  Google Scholar 

  58. Wernick, M.N., Yang, Y., Brankov, J.G., Yourganov, G., Strother, S.C.: Machine learning in medical imaging. IEEE Signal Process. Mag. 27(4), 25–38 (2010)

    Article  Google Scholar 

  59. Powell, S., Magnotta, V.A., Johnson, H., Jammalamadaka, V.K., Pierson, R., Andreasen, N.C.: Registration and machine learning-based automated segmentation of subcortical and cerebellar brain structures. NeuroImage 39(1), 238–247 (2008)

    Article  Google Scholar 

  60. Ling, H., Zhou, S.K., Zheng, Y., Georgescu, B., Sühling, M., Comaniciu, D.: Hierarchical, learning-based automatic liver segmentation. In: CVPR 2008, pp. 1–8 (2008)

    Google Scholar 

  61. Glocker, B., Zikic, D., Haynor, D.R.: Robust registration of longitudinal spine CT. Med. Image Comput. Comput. Assist. Interv. 17, 251–258 (2014)

    Google Scholar 

  62. Wang, Z., Ma, Y.: Medical image fusion using m-PCNN. Inf. Fus. 9(2), 176–185 (2008)

    Article  Google Scholar 

  63. Deselaers, T., Deserno, T.M., Müller, H.: Automatic medical image annotation in ImageCLEF 2007: overview, results, and discussion. Pattern Recogn. Lett. 29(15), 1988–1995 (2008)

    Article  Google Scholar 

  64. Müller, H., Michoux, N., Bandon, D., Geissbuhler, A.: A review of content-based image retrieval systems in medical applications—clinical benefits and future directions. Int. J. Med. Inf. 73(1), 1–23 (2004)

    Article  Google Scholar 

  65. Shen, D., Wu, G., Zhang, D., Suzuki, K., Wang, F., Yan, P.: Machine learning in medical imaging. Comput. Med. Imaging Grap. Official J. Comput. Med. Imaging Soc. 41, 1–2 (2015)

    Article  Google Scholar 

  66. Singh, S.: Review on machine learning techniques for automatic segmentation of liver images. Int. J. Adv. Res. Comput. Sci. Softw. Eng. 3(4), 666–670 (2013)

    Google Scholar 

  67. Van Ginneken, B., Heimann, T., Styner, M.: 3D segmentation in the clinic: a grand challenge. In: 3D Segmentation in the Clinic: A Grand Challenge, pp. 7–15 (2007)

    Google Scholar 

  68. Metz, C., Schaap, M., van Walsum, T., van der Giessen, A., Weustink, A., Mollet, N., Krestin, G., Niessen, W.: 3D segmentation in the clinic: a grand challenge II-coronary artery tracking. Insight J. 1(5), 6 (2008)

    Google Scholar 

  69. Angelini, E.D., Clatz, O., Mandonnet, E., Konukoglu, E., Capelle, L., Duffau, H.: Glioma dynamics and computational models: a review of segmentation, registration, and in silico growth algorithms and their clinical applications. Curr. Med. Imaging Rev. 3, 262–276 (2007)

    Article  Google Scholar 

  70. Bauer, S., Wiest, R., Nolte, L.P., Reyes, M.: A survey of MRI- based medical image analysis for brain tumor studies. Phys. Med. Biol. 58, R97–R129 (2013)

    Article  Google Scholar 

  71. Menze, B.H., et al.: The multimodal brain tumor image segmentation benchmark (BRATS). IEEE Trans. Med. Imaging 34(10), 1993–2024 (2015)

    Article  Google Scholar 

  72. Shattuck, D.W., Prasad, G., Mirza, M., Narr, K.L., Toga, A.W.: Online resource for validation of brain segmentation methods. Neuroimage 45(2), 431–439 (2009)

    Article  Google Scholar 

  73. Deselaers, T., Müller, H., Clough, P., Ney, H., Lehmann, T.M.: The CLEF 2005 automatic medical image annotation task. Int. J. Comput. Vis. 74(1), 51–58 (2007)

    Article  Google Scholar 

  74. Peters, C., et al. (eds.): CLEF 2008. LNCS, vol. 5706. Springer, Heidelberg (2009)

    Google Scholar 

  75. Peters, C., Caputo, B., Gonzalo, J., Jones, G.J.F., Kalpathy-Cramer, J., Müller, H., Tsikrika, T. (eds.): CLEF 2009. LNCS, vol. 6242. Springer, Heidelberg (2010)

    Google Scholar 

  76. Lehmann, T.M., Schubert, H., Keysers, D., Kohnen, M., Wein, B.B.: The IRMA code for unique classification of medical images. In: Medical Imaging 2003, pp. 440–451. International Society for Optics and Photonics (2003)

    Google Scholar 

  77. Mueen, A., Zainuddin, R., Baba, M.S.: Automatic multilevel medical image annotation and retrieval. J. Digital Imaging 21(3), 290–295 (2007)

    Article  Google Scholar 

  78. Ko, B.C., Lee, J., Nam, J.Y.: Automatic medical image annotation and keyword-based image retrieval using relevance feedback. J. Digital Imaging 25(4), 454–465 (2011)

    Article  Google Scholar 

  79. Wei, C.H., Chen, S.Y.: Annotation of Medical Images (2012)

    Google Scholar 

  80. An, K., Prasad, B.G.: Automated image annotation for semantic indexing and retrieval of medical images. Int. J. Comput. Appl. 55(3), 26–33 (2012)

    Google Scholar 

  81. Burdescu, D.D., Mihai, C.G., Stanescu, L., Brezovan, M.: Automatic image annotation and semantic based image retrieval for medical domain. Neurocomputing 109, 33–48 (2013)

    Article  Google Scholar 

  82. Dumitru, D.B., Stanescu, L., Brezovan, M.: Information extraction from medical images: evaluating a novel automatic image annotation system using semantic-based visual information retrieval (2014)

    Google Scholar 

  83. Villena Román, J., González Cristóbal, J.C., Goñi Menoyo, J.M., Martínez Fernández, J.L.: Miracles naive approach to medical images annotation (2005)

    Google Scholar 

  84. Setia, L., Teynor, A., Halawani, A., Burkhardt, H.: Grayscale medical image annotation using local relational features. Pattern Recognit. Lett. 29(15), 2039–2045 (2008)

    Article  Google Scholar 

  85. Khademi, S.M., Pakize, S.R., Tanoorje, M.A.: A review of methods for the automatic annotation and retrieval of medical images. Int. J. Adv. Res. Comput. Sci. Softw. Eng. 4(7), 1–5 (2014)

    Google Scholar 

  86. Wang, M., Hua, X.S.: Active learning in multimedia annotation and retrieval: a survey. ACM Trans. Intell. Syst. Technol. 2(2), 10 (2011)

    Article  MathSciNet  Google Scholar 

  87. Tang, J., Zha, Z.J., Tao, D., Chua, T.S.: Semantic-gap-oriented active learning for multilabel image annotation. IEEE Trans. Image Process. 21(4), 2354–2360 (2012)

    Article  MathSciNet  Google Scholar 

  88. Ciresan, D., Meier, U., Schmidhuber, J.: Multi-column deep neural networks for image classification. In: 2012 IEEE Conference on Computer Vision and Pattern Recognition (CVPR), pp. 3642–3649. IEEE (2012)

    Google Scholar 

  89. Krizhevsky, A., Sutskever, I., Hinton, G.E.: Imagenet classification with deep convolutional neural networks. In: Advances in Neural Information Processing Systems, pp. 1097–1105 (2012)

    Google Scholar 

  90. Ciresan, D., Giusti, A., Gambardella, L.M., Schmidhuber, J.: Deep neural networks segment neuronal membranes in electron microscopy images. In: Advances in Neural Information Processing Systems, pp. 2843–2851 (2012)

    Google Scholar 

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Menasalvas, E., Gonzalo-Martin, C. (2016). Challenges of Medical Text and Image Processing: Machine Learning Approaches. In: Holzinger, A. (eds) Machine Learning for Health Informatics. Lecture Notes in Computer Science(), vol 9605. Springer, Cham. https://doi.org/10.1007/978-3-319-50478-0_11

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