The MedGIFT Group at ImageCLEF 2009

MedGIFT is a medical imaging research group of the Geneva University Hospitals and the University of Geneva, Switzerland. Since 2004, the medGIFT group has participated in the ImageCLEF benchmark each year, focusing mainly on the medical imaging tasks. For the medical image retrieval task, two existing retrieval engines were used: the GNU Image Finding Tool (GIFT) as image retrieval engine and Apache Lucene as textual retrieval engine. To improve the retrieval performance, automatic query expansion was used. In total, 13 runs were submitted as well for the image–based topics and the case–based topics. The baseline setup used for the past five years already obtained the best result among all our visual submissions. For the medical image annotation task, two approaches were tested. One approach is using GIFT for image retrieval and kNN (k–Nearest Neighbors) for the classification, which was already used for the past 5 years. The second approach used Scale–Invariant Feature Transform (SIFT) technology with a Support Vector Machine (SVM) classifier. Three runs were submitted in total, two with the GIFT–kNN–based approach and one using a combination of the SIFT–SVM–based approach and GIFT–kNN–based approach. For the medical image classification task, the GIFT–kNN–based approach gives stable results, although not in the quality of the best groups. The SIFT–SVM– based approach implementation did not achieve the expected better performance. We think that the SVM kernel may be a key factor that requires further optimization.