Enhanced Structural Brain Connectivity Analyses Using High Diffusion-weighting Strengths

Tractography is a unique modality for the in vivo measurement of structural connectivity, crucial for understanding brain networks and neurological conditions. With increasing b -value, the diffusion-weighting signal becomes primarily sensitive to the intra-axonal signal. However, it remains unclear how tractography is affected by this observation. Here, using open-source datasets, we showed that at high b -values, DWI reduces the uncertainty in estimating fiber orientations. Specifically, we found the ratio of biologically-meaningful longer-range connections increases, accompanied with downstream impact of redistribution of connectome and network metrics. However, when going beyond b =6000 s/mm ² , the loss of SNR imposed a penalty. Lastly, we showed that the data reaches satisfactory reproducibility with b -value above 1200 s/mm ² . Overall, the results suggest that using b -values above 2500 s/mm ² is essential for more accurate connectome reconstruction by reducing uncertainty in fiber orientation estimation, supporting the use of higher b -value protocols in standard diffusion MRI scans and pipelines.