Enhancement of clustering techniques by coupling clustering tree and neural network: Application to brain tumour segmentation.

Currently, no classical clustering algorithm is efficient on its own. The predefined number of clusters required for their operation does not consistently produce satisfactory segmentation results. They exhibit cluster instability, are vulnerable to the local optimum trap, and are sensitive to noise and imaging artefacts. Most contributions designed to overcome these drawbacks incorporate prior knowledge such as cluster label information and statistic measures that demand minimal labelled training data. Although these approaches improve the segmentation accuracy, they tend to diminish the advantages of clustering algorithms over the supervised learning methods. This study proposes a shift from the use of a predefined number of clusters to a clustering tree‐based method for performance enhancement of classical clustering algorithms. The proposed method is a three‐stage algorithm. It begins with the extraction of low‐level features from a clustering tree. Clustering trees are sets of labelled clusters of an image at multiple clustering resolutions. The second stage extracts high‐level features by coupling the clustering tree to a single‐layer feedforward neural network. The third stage is the classification stage, where the basic model of a neural network extracts the tumour from a high‐level feature map. Because neither of the neural networks requires training, the proposed method is both fully unsupervised and fully automated and retains all its advantages over supervised methods. A performance evaluation using FLAIR MRI images of brain tumour patients from the BRATS2015 and BRATS2020 databases demonstrates significant performance enhancement over four classical clustering algorithms and two of the four proposed techniques were comparable to deep learning methods. [ABSTRACT FROM AUTHOR]