Vessel Orientation Constrained Quantitative Susceptibility Mapping (QSM) Reconstruction

Abstract

QSM is used to estimate the underlying tissue magnetic susceptibility and oxygen saturation in veins. This paper presents vessel orientation as a new regularization term to improve the accuracy of \(l_1\) regularized QSM reconstruction in cerebral veins. For that purpose, the vessel tree is first extracted from an initial QSM reconstruction. In a second step, the vascular geometric prior is incorporated through an orthogonality constraint into the QSM reconstruction. Using a multi-orientation QSM acquisition as gold standard, we show that the QSM reconstruction obtained with the vessel anatomy prior provides up to 40 % RMSE reduction relative to the baseline \(l_1\) regularizer approach. We also demonstrate in vivo OEF maps along venous veins based on segmentations from QSM. The utility of the proposed method is further supported by inclusion of a separate MRI venography scan to introduce more detailed vessel orientation information into the reconstruction, which provides significant improvement in vessel conspicuity.