The aim of this work was to test the most popular and essential algorithms of the intensity nonuniformity correction of the breast MRI imaging. In this type of MRI imaging, especially in the proximity of the coil, the signal is strong but also can produce some inhomogeneities. Evaluated methods of signal correction were: N3, N3FCM, N4, Nonparametric, and SPM. For testing purposes, a uniform phantom object was used to obtain test images using breast imaging MRI coil. To quantify the results, two measures were used: integral uniformity and standard deviation. For each algorithm minimum, average and maximum values of both evaluation factors have been calculated using the binary mask created for the phantom. In the result, two methods obtained the lowest values in these measures: N3FCM and N4, however, for the second method visually phantom was the most uniform after correction.
Image segmentation is often used in medical image processing. This crucial task can affect all results obtained from the further steps of image analysis. In nuclear medicine emission tomography imaging, where acquired and reconstructed images contain large noise and high blurring level, segmentation and tumour boundaries delineation can be very challenging task. Many from already existing image segmentation methods are based on clustering. In this work, we have tested and implemented a few clustering based methods. We have mainly focused on k-means related algorithms to evaluate and compare their accuracy. In this group we have chosen k-means algorithm, k-medoid clustering, and fuzzy C-means (FCM) method. Results for all methods were verified using the gold standard obtained from anatomical image co-registered and emission tomography dataset. Numerical values of both datasets matching were calculated using the Jaccard index. Results were compared with standard segmentation algorithm based on fixed threshold (standardized uptake value - SUV with threshold 2.5), which is a commonly used standard in clinical practice and also with previously implemented and verified methods (including game theoretical algorithm). For all tested methods we have obtained very similar results, comparable to SUV 2.5 threshold method but worse than the game theoretic method.