Multi-echo acquisition of MR angiography and venography of the brain at 3 Tesla

To improve the visibility of veins in susceptibility-weighted imaging (SWI) using a multi-gradient echo acquisition.

A three-dimensional multi-echo gradient-echo pulse sequence was developed for simultaneous acquisition of MR angiography and multiple volumes of MR venography (MRV) of the brain. The first echo was acquired for MR angiography using the time-of-flight in-flow effect. The subsequent echoes were acquired for SWI-based MRV at different echo times (TEs).

Multiple MRV datasets acquired at different TEs were complementary in depicting the venous vasculature. MRV data acquired at a longer TE had a higher venous contrast and stronger susceptibility weighting, whereas MRV data acquired at a shorter TE had a higher signal-to-noise ratio and less severe off-resonance artifacts. Three-dimensional mapping of local field gradients was calculated and the transverse relaxivity (R(2)) at each voxel was quantified using multi-TE exponential fitting.

Multi-echo acquisition of MR angiography and venography demonstrated improved visibility of venous vasculature especially in regions with severe field inhomogeneity compared with conventional acquisition of SWI and dual-echo acquisition of MR angiography and venography.