  Brain tumor segmentation from magnetic resonance imaging (MRI) plays an
important role in diagnostic radiology. To overcome the practical issues in
manual approaches, there is a huge demand for building automatic tumor
segmentation algorithms. This work introduces an efficient brain tumor
summation model by exploiting the advancement in MRI and graph neural networks
(GNNs). The model represents the volumetric MRI as a region adjacency graph
(RAG) and learns to identify the type of tumors through a graph attention
network (GAT) -- a variant of GNNs. The ablation analysis conducted on two
benchmark datasets proves that the proposed model can produce competitive
results compared to the leading-edge solutions. It achieves mean dice scores of
0.91, 0.86, 0.79, and mean Hausdorff distances in the 95th percentile (HD95) of
5.91, 6.08, and 9.52 mm, respectively, for whole tumor, core tumor, and
enhancing tumor segmentation on BraTS2021 validation dataset. On average, these
performances are >6\% and >50%, compared to a GNN-based baseline model,
respectively, on dice score and HD95 evaluation metrics.
