Tham khảo tài liệu 'data analysis machine learning and applications episode 1 part 3', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Computer Assisted Classification of Brain Tumors Norbert Rohrl1 José R. Iglesias-Rozas2 and Galia Weidl1 1 Institut fur Analysis Dynamik und Modellierung Universitat Stuttgart Pfaffenwaldring 57 70569 Stuttgart Germany roehrl@ 2 Katharinenhospital Institut fur Pathologie Neuropathologie Kriegsbergstr. 60 70174 Stuttgart Germany Abstract. The histological grade of a brain tumor is an important indicator for choosing the treatment after resection. To facilitate objectivity and reproducibility Iglesias et al. 1986 proposed to use a standardized protocol of 50 histological features in the grading process. We tested the ability of Support Vector Machines SVM Learning Vector Quantization LVQ and Supervised Relevance Neural Gas SRNG to predict the correct grades of the 794 astrocytomas in our database. Furthermore we discuss the stability of the procedure with respect to errors and propose a different parametrization of the metric in the SRNG algorithm to avoid the introduction of unnecessary boundaries in the parameter space. 1 Introduction Although the histological grade has been recognized as one of the most powerful predictors of the biological behavior of tumors and significantly affects the management of patients it suffers from low inter- and intraobserver reproducibility due to the subjectivity inherent to visual observation. The common procedure for grading is that a pathologist looks at the biopsy under a microscope and then classifies the tumor on a scale of 4 grades from I to IV see Fig. 1 . The grades roughly correspond to survival times a patient with a grade I tumor can survive 10 or more years while a patient with a grade IV tumor dies with high probability within 15 month. Iglesias et al. 1986 proposed to use a standardized protocol of 50 histological features in addition to make grading of tumors reproducible and to provide data for statistical analysis and classification. The presence of these 50 .
