# Building AI That Learns and Adapts: A Case Study in MRI Diagnostics - Agata Chudzińska

## Executive summary

This technical talk explores Continual Learning (CL), positioning it as a critical missing piece for building robust, adaptive AI systems. Using a case study in MRI diagnostics for detecting Focal Cortical Dysplasias (FCDs) in epilepsy patients, the speaker details how CL techniques mitigate issues like data drift and catastrophic forgetting. The presentation covers advanced ML architectures (Encoder-Decoder), preprocessing steps (e.g., segmentation, Junction/Extension filters), and three main CL methods: regularization-based, memory-based, and architecture-based. The goal is to enable models to adapt continuously in privacy-sensitive environments without requiring full retraining.

## Key takeaways

- Continual Learning (CL) addresses core ML deployment challenges.: CL allows AI models to learn and adapt over time from new data streams without forgetting previously acquired knowledge, solving issues like catastrophic forgetting and data drift. This is crucial for high-stakes fields like medicine.
- Medical imaging requires specialized preprocessing and architectures.: For FCD detection from MRI scans, the process involves brain tissue segmentation and applying feature enhancement filters (e.g., Junction and Extension) before feeding data into an Encoder-Decoder variant of a neural network architecture.
- CL methods offer solutions for resource constraints.: Instead of retraining from scratch (which is costly, time-consuming, and raises privacy concerns), CL utilizes regularization-based, memory-based, or architecture-based approaches to maintain performance while adapting to new tasks.
- The future of AI requires continuous adaptation.: The speaker emphasizes that CL is not just a 'nice to have' feature but a strategic architectural choice for any production-level ML system dealing with evolving data and strict privacy requirements.

## Technical details

- Focal Cortical Dysplasias (FCDs) in MRI: FCDs are errors in brain development, responsible for over 70% of pharmacoresistant epilepsy. Detection relies on identifying subtle features like blurry boundaries between gray and white matter, unusual surface foldings, and the transmantle sign.
- ML Architecture (Encoder-Decoder): The chosen architecture is a variant of the Encoder-Decoder structure. It works by compressing input data into a latent space (encoding) and then reconstructing or segmenting the information (decoding), allowing the network to learn critical features like edges and shapes.
- Data Preprocessing Filters: Two key filters were used: 'Junction,' which applies standard deviation and mean on pixel intensities to expose hyperintensities; and 'Extension,' which leverages blurring to highlight subtle abnormalities.
- Continual Learning Methods: Three main approaches were discussed: 1) Regularization-based (penalizing parameter changes); 2) Replay/Memory-based (storing synthetic or real data in a buffer, inspired by sleep); and 3) Architecture-based (dynamically expanding the network with new layers).
- Advanced CL Research: Nested Learning: A newer paradigm proposed for continual learning is 'Nested Learning,' suggesting that ML models should not be treated as a single optimization problem but rather run through multiple, interacting optimization loops.

## Practical implications

- Implementing CL is vital for medical AI systems to maintain performance and reliability when data distributions change (data drift) or new pathologies are introduced.
- The model's output must prioritize explainability (segmentation masks) to meet strict medical certification requirements, making 'black box' models unsuitable.
- For build engineers, CL represents a shift from monolithic retraining pipelines to continuous, incremental model updates, significantly reducing computational cost and time.

## Topics

Continual Learning, Machine Learning Architecture, Medical Imaging (MRI), Deep Learning, Data Drift Mitigation, Epilepsy Research

Source: https://www.youtube.com/watch?v=dWQMhrIt5XE