Abstract
Purpose
To reduce the off‐resonance artifact in susceptibility‐weighted imaging (SWI)‐based MR venography (MRV) in the brain regions with severe field inhomogeneity and to reduce the signal loss in the minimum‐intensity projection (mIP) display of the 3D MRV.
Materials and Methods
A novel postprocessing approach was presented to map the local field gradients (LFGs) using the 3D SWI data without phase‐unwrapping. LFG measurements were used to assess the severity of field inhomogeneity and suppress the residual phase in the phase mask induced by the off‐resonance effect. Volume segmentation of brain tissue was used to reduce the signal loss in the peripheral regions of the brain in the through‐plane mIP images and enable in‐plane mIP display of MRV.
Results
Off‐resonance artifact in the brain regions with severe field inhomogeneity was effectively reduced by the LFG‐based phase suppression approach. Signal loss was reduced in the through‐plane mIP of MRV using volume segmentation of brain tissue prior to projection. In‐plane mIP of MRV also became feasible with volume segmentation.
Conclusion
Off‐resonance artifacts and signal loss in mIP display of MRV can be effectively reduced through postprocessing. J. Magn. Reson. Imaging 2008;28:327–333. © 2008 Wiley‐Liss, Inc.