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. (c) 2008 Wiley-Liss, Inc.
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. (c) 2008 Wiley-Liss, Inc.
Authors: J R Reichenbach; M Barth; E M Haacke; M Klarhöfer; W A Kaiser; E Moser Journal: J Comput Assist Tomogr Date: 2000 Nov-Dec Impact factor: 1.826
Authors: I L Tan; R A van Schijndel; P J Pouwels; M A van Walderveen; J R Reichenbach; R A Manoliu; F Barkhof Journal: AJNR Am J Neuroradiol Date: 2000 Jun-Jul Impact factor: 3.825
Authors: J R Reichenbach; L Jonetz-Mentzel; C Fitzek; E M Haacke; D K Kido; B C Lee; W A Kaiser Journal: Neuroradiology Date: 2001-05 Impact factor: 2.804
Authors: Nathaniel D Wycliffe; Judy Choe; Barbara Holshouser; Udo E Oyoyo; E Mark Haacke; Daniel K Kido Journal: J Magn Reson Imaging Date: 2004-09 Impact factor: 4.813