Quantitative Oxygenation Venography from MRI Phase

Purpose: To demonstrate acquisition and processing methods for quantitative oxygenation venograms that map in vivo oxygen saturation (SvO(2)) along cerebral venous vasculature. Methods: Regularized quantitative susceptibility mapping (QSM) is used to reconstruct susceptibility values and estimate SvO(2) in veins. QSM with l(1) and l(2) regularization are compared in numerical simulations of vessel structures with known magnetic susceptibility. Dual-echo, flow-compensated phase images are collected in three healthy volunteers to create QSM images. Bright veins in the susceptibility maps are vectorized and used to form a three-dimensional vascular mesh, or venogram, along which to display SvO(2) values from QSM. Results: Quantitative oxygenation venograms that map SvO(2) along brain vessels of arbitrary orientation and geometry are shown in vivo. SvO(2) values in major cerebral veins lie within the normal physiological range reported by O-15 positron emission tomography. SvO(2) from QSM is consistent with previous MR susceptometry methods for vessel segments oriented parallel to the main magnetic field. In vessel simulations, l(1) regularization results in less than 10% SvO(2) absolute error across all vessel tilt orientations and provides more accurate SvO(2) estimation than l(2) regularization. Conclusion: The proposed analysis of susceptibility images enables reliable mapping of quantitative SvO(2) along venograms and may facilitate clinical use of venous oxygenation imaging. (C) 2013 Wiley Periodicals, Inc.