Penalized Geodesic Tractography for Mitigating Gyral Bias.

In this paper, we introduce a penalized geodesic tractography (PGT) algorithm for mitigating gyral bias in cortical tractography, which is essential for improving cortical connectomics. Unlike deterministic and probabilistic tractography algorithms that perform one-way tracking, PGT solves a global optimization problem in estimating the pathways connecting multiple regions, instead of local step-by-step orientation tracing. PGT is unconfounded by local false-positive or false-negative fiber orientations and ensures that fiber streamlines that are intended to connect two regions do not terminate prematurely. We show that PGT reduces gyral bias by allowing streamlines to make sharper turns into the cortical gyral matter and results in a significantly more uniform spatial distribution of cortical connections.