CALF: A Conditionally Adaptive Loss Function to Mitigate Class-Imbalanced Segmentation
This addresses segmentation challenges in medical diagnostics due to imbalanced data, such as rare cases or small ROIs, but is incremental as it builds on existing loss function adaptations.
The paper tackles the problem of class-imbalanced datasets in medical image segmentation by proposing a conditionally adaptive loss function (CALF) that uses statistical methods to estimate imbalance severity and apply transformations, resulting in substantial segmentation improvements validated on large-scale datasets like UPENN-GBM and BraTS.
Imbalanced datasets pose a considerable challenge in training deep learning (DL) models for medical diagnostics, particularly for segmentation tasks. Imbalance may be associated with annotation quality limited annotated datasets, rare cases, or small-scale regions of interest (ROIs). These conditions adversely affect model training and performance, leading to segmentation boundaries which deviate from the true ROIs. Traditional loss functions, such as Binary Cross Entropy, replicate annotation biases and limit model generalization. We propose a novel, statistically driven, conditionally adaptive loss function (CALF) tailored to accommodate the conditions of imbalanced datasets in DL training. It employs a data-driven methodology by estimating imbalance severity using statistical methods of skewness and kurtosis, then applies an appropriate transformation to balance the training dataset while preserving data heterogeneity. This transformative approach integrates a multifaceted process, encompassing preprocessing, dataset filtering, and dynamic loss selection to achieve optimal outcomes. We benchmark our method against conventional loss functions using qualitative and quantitative evaluations. Experiments using large-scale open-source datasets (i.e., UPENN-GBM, UCSF, LGG, and BraTS) validate our approach, demonstrating substantial segmentation improvements. Code availability: https://anonymous.4open.science/r/MICCAI-Submission-43F9/.