Interpretable Deep Learning for Brain Tumor Classification and Severity Assessment Using CNN and Transfer Learning
摘要
To improve treatment plans and patient outcomes, brain tumors must be accurately and promptly identified. This research introduces a unified and interpretable deep learning model aimed at classifying brain tumors using MRI images. The study leverages a structured dataset comprising 7023 MRI scans, distributed across four distinct categories: glioma, meningioma, pituitary tumor, and healthy (no tumor) cases. An entirely custom convolutional neural network achieved an 85% validation accuracy. Additionally, three models for transfer learning–DenseNet121, VGG16, and ResNet50–were put into practice and evaluated in comparison. Without the need for base layer fine-tuning, VGG16 produced an accuracy of 88%, ResNet50 84%, and DenseNet121 92%. The proposed framework incorporates several diagnostic visualization techniques to improve interpretability and clinical relevance: hemispheric dominance analysis using region-wise activation segmentation, severity classification based on spatial activation area thresholds, tumor localization using Grad-CAM heatmaps, and a novel fusion-based severity scoring mechanism that combines grayscale pixel distribution and Grad-CAM activation intensity. In order to investigate model limitations, a thorough misclassification analysis was carried out with the use of visual overlays. To validate the effectiveness of the models, a diverse set of evaluation tools was employed, including class-wise confusion matrices, ROC-AUC analysis, and statistical indicators such as precision, recall, and the F1 metric. This study offers a useful and reliable tool to help radiologists with real-time brain tumor detection and clinical decision-making by improving interpretability in addition to delivering competitive classification performance.