Brain MR Image Synthesis with 3D Multi-Contrast Self-Attention GAN

TL;DR

This paper introduces a novel 3D GAN framework that synthesizes missing brain MRI contrasts from a single modality, ensuring high fidelity and tumour preservation, thus reducing scan time and cost.

Contribution

The proposed 3D-MC-SAGAN employs a hybrid attention mechanism and segmentation constraints to generate multiple MRI contrasts with state-of-the-art quality and tumour consistency.

Findings

Achieves superior quantitative performance in MRI synthesis tasks.

Produces anatomically plausible and visually coherent contrast images.

Maintains tumour segmentation accuracy comparable to fully acquired multi-modal data.

Abstract

Complete and high-quality multi-modal Magnetic Resonance Imaging (MRI) is essential for accurate neuro-oncological assessment, as each contrast provides complementary anatomical and pathological information. However, acquiring all modalities (e.g., T1c, T1n, T2w, T2f) for every patient is often impractical due to prolonged scan times, cost, and patient discomfort, potentially limiting comprehensive tumour evaluation. We propose 3D-MC-SAGAN (3D Multi-Contrast Self-Attention Generative Adversarial Network), a unified 3D multi-contrast synthesis framework that generates high-fidelity missing modalities from a single T2w input while explicitly preserving tumour characteristics. The model employs a multi-scale 3D encoder--decoder generator with residual connections and a novel Memory-Bounded Hybrid Attention (MBHA) block to capture long-range dependencies efficiently, and is trained with a WGAN-GP critic and an auxiliary domain classification head to produce T2f, T1n, and T1c volumes within a unified network. To ensure anatomical and pathological fidelity, we incorporate a frozen 3D U-Net-based segmentation network that enforces a tumour-consistency constraint during training. A composite objective combining adversarial, reconstruction, perceptual, structural similarity, contrast-classification, and segmentation-guided losses further promotes both global realism and tumour-preserving structure. Extensive experiments on 3D brain MRI datasets demonstrate that 3D-MC-SAGAN achieves state-of-the-art quantitative performance and produces visually coherent, anatomically plausible contrasts with improved distributional realism. Importantly, the proposed method maintains tumour segmentation accuracy comparable to that achieved using fully acquired multi-modal inputs, highlighting its potential to reduce acquisition burden while preserving clinically meaningful information.