Two-Stage Approach for Brain MR Image Synthesis: 2D Image Synthesis and 3D Refinement

TL;DR

This paper introduces a two-stage brain MRI synthesis method combining 2D slice-based synthesis with 3D refinement, reducing artifacts and improving tumor segmentation accuracy.

Contribution

It presents a novel intensity encoding technique for 2D MRI synthesis and a 3D refinement step to enhance image quality and segmentation performance.

Findings

Intensity encoding reduces synthesis artifacts

Refiner improves MRI quality and segmentation accuracy

Method enhances practical brain tumor analysis

Abstract

Despite significant advancements in automatic brain tumor segmentation methods, their performance is not guaranteed when certain MR sequences are missing. Addressing this issue, it is crucial to synthesize the missing MR images that reflect the unique characteristics of the absent modality with precise tumor representation. Typically, MRI synthesis methods generate partial images rather than full-sized volumes due to computational constraints. This limitation can lead to a lack of comprehensive 3D volumetric information and result in image artifacts during the merging process. In this paper, we propose a two-stage approach that first synthesizes MR images from 2D slices using a novel intensity encoding method and then refines the synthesized MRI. The proposed intensity encoding reduces artifacts when synthesizing MRI on a 2D slice basis. Then, the \textit{Refiner}, which leverages complete 3D volume information, further improves the quality of the synthesized images and enhances their applicability to segmentation methods. Experimental results demonstrate that the intensity encoding effectively minimizes artifacts in the synthesized MRI and improves perceptual quality. Furthermore, using the \textit{Refiner} on synthesized MRI significantly improves brain tumor segmentation results, highlighting the potential of our approach in practical applications.