Locus Coeruleus Visualisation at 7T: Optimisation through Multi-Contrast Acquisition and Wavelet-Based Fusion

Motivation: Magnetisation transfer (MT) weighting has been used to visualise the Locus Coeruleus (LC) at 7T, but robust visualisation remains challenging due to its small size and complex contrast mechanisms. Goal(s): Investigate how proton-density- (PD) and T1-weighting interact with MT-weighting and optimise an advanced post-processing pipeline for LC visualisation. Approach: Multi-echo 3D gradient echo images were acquired with MT-weighting and either PD- or T1-weighting from two individuals, including scan-rescan acquisitions. Results: MT-PD-weighting enhanced visualisation of the LC with respect to the surrounding tissue, whereas MT-T1-weighting enhanced contrast with respect to the nearby CSF. Combining these via wavelet-based fusion maximises these respective benefits. Impact: Enhancing visualisation of the Locus Coeruleus with our proposed acquisition and processing technique will pave the way for neurologists and cognitive neuroscientists to understand the key role this structure plays in human cognition and neurodegeneration.