Stroke Lesion Segmentation in FLAIR MRI Datasets Using Customized Markov Random Fields

Robust and reliable stroke lesion segmentation is a crucial step toward employing lesion volume as an independent endpoint for randomized trials. The aim of this work was to develop and evaluate a novel method to segment sub-acute ischemic stroke lesions from fluid-attenuated inversion recovery (FLAIR) magnetic resonance imaging (MRI) datasets. After preprocessing of the datasets, a Bayesian technique based on Gabor textures extracted from the FLAIR signal intensities is utilized to generate a first estimate of the lesion segmentation. Using this initial segmentation, a customized voxel-level Markov random field model based on intensity as well as Gabor texture features is employed to refine the stroke lesion segmentation. The proposed method was developed and evaluated based on 151 multi-center datasets from three different databases using a leave-one-patient-out validation approach. The comparison of the automatically segmented stroke lesions with manual ground truth segmentation revealed an average Dice coefficient of 0.582, which is in the upper range of previously presented lesion segmentation methods using multi-modal MRI datasets. Furthermore, the results obtained by the proposed technique are superior compared to the results obtained by two methods based on convolutional neural networks and three phase level-sets, respectively, which performed best in the ISLES 2015 challenge using multi-modal imaging datasets. The results of the quantitative evaluation suggest that the proposed method leads to robust lesion segmentation results using FLAIR MRI datasets only as a follow-up sequence

The Multimodal Brain Tumor Image Segmentation Benchmark (BRATS)

In this paper we report the set-up and results of the Multimodal Brain Tumor Image Segmentation Benchmark (BRATS) organized in conjunction with the MICCAI 2012 and 2013 conferences. Twenty state-of-the-art tumor segmentation algorithms were applied to a set of 65 multi-contrast MR scans of low-and high-grade glioma patients-manually annotated by up to four raters-and to 65 comparable scans generated using tumor image simulation software. Quantitative evaluations revealed considerable disagreement between the human raters in segmenting various tumor sub-regions (Dice scores in the range 74%-85%), illustrating the difficulty of this task. We found that different algorithms worked best for different sub-regions (reaching performance comparable to human inter-rater variability), but that no single algorithm ranked in the top for all sub-regions simultaneously. Fusing several good algorithms using a hierarchical majority vote yielded segmentations that consistently ranked above all individual algorithms, indicating remaining opportunities for further methodological improvements. The BRATS image data and manual annotations continue to be publicly available through an online evaluation system as an ongoing benchmarking resource.This research was supported by the NIH NCRR (P41-RR14075), the NIH NIBIB (R01EB013565), the Academy of Finland (133611), TEKES (ComBrain), the Lundbeck Foundation (R141-2013-13117), the Swiss Cancer League, the Swiss Institute for Computer Assisted Surgery (SICAS), the NIH NIBIB NAMIC (U54-EB005149), the NIH NCRR NAC (P41-RR13218), the NIH NIBIB NAC (P41-EB-015902), the NIH NCI (R15CA115464), the European Research Council through the ERC Advanced Grant MedYMA 2011-291080 (on Biophysical Modeling and Analysis of Dynamic Medical Images), the FCT and COMPETE (FCOM-01-0124-FEDER-022674), the MICAT Project (EU FP7 Marie Curie Grant No. PIRG-GA-2008-231052), the European Union Seventh Framework Programme under grant agreement no. 600841, the Swiss NSF project Computer Aided and Image Guided Medical Interventions (NCCR CO-ME), the Technische Universitat Munchen-Institute for Advanced Study (funded by the German Excellence Initiative and the European Union Seventh Framework Programme under Grant agreement 291763), the Marie Curie COFUND program of the European Union (Rudolf Mossbauer Tenure-Track Professorship to BHM).info:eu-repo/semantics/publishedVersio