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Brain MRI Tumor Segmentation

Investigated multiple 3D medical image segmentation architectures for brain tumor delineation using the BraTS dataset, evaluating baseline and attention-enhanced models.

PyTorch3D U-NetAttention U-NetEfficientNetBraTSMONAIMixed Precision

SYSTEM ARCHITECTURE

SYSTEM ARCHITECTURE3D U-Net → EfficientNet → Attention pipelineBraTS 20203D MRI volumesPreprocessingNormalization + patchesBaseline 3D U-NetDice 0.8057EfficientNet U-NetDice 0.8157Attention + EfficientNetDice 0.8256ValidationDice + segmentation metricsBest validation Dice: 0.8256 using the Attention + EfficientNet architecture.

Best validation Dice: 0.8256 using the Attention + EfficientNet architecture.

Problem

Brain tumor segmentation requires accurate volumetric understanding across noisy medical scans, with strong constraints on precision and clinical interpretability.

Architecture

3D segmentation pipeline evaluating baseline and attention-enhanced encoder-decoder architectures on BraTS data, with patch-based training and mixed-precision optimization.

Challenges

  • Handled volumetric 3D MRI inputs with patch-based training
  • Compared baseline 3D U-Net and attention-enhanced variants
  • Balanced segmentation quality with memory limits on large 3D tensors
  • Tuned loss functions for class imbalance in tumor regions
  • Optimized GPU memory with mixed precision and gradient checkpointing

Benchmarks

BraTS dataset, 128×128×128 patch size. Validation Dice progression: baseline 3D U-Net 0.8057 → EfficientNet encoder 0.8157 → Attention U-Net + EfficientNet 0.8256 (+1.99 pp improvement over baseline). Mixed precision training with MONAI.

Lessons Learned

  • Attention mechanisms can improve localization in medical volumes
  • 3D models are memory-bound quickly, so training strategy matters
  • Dice-based objectives are essential for imbalanced segmentation tasks
  • Incremental experimentation beats architectural complexity