Junmin Liu1, Maria Drangova1,2. 1. Imaging Research Laboratories, Robarts Research Institute, Schulich School of Medicine & Dentistry, University of Western Ontario, London, Canada. 2. Department of Medical Biophysics, Schulich School of Medicine & Dentistry, University of Western Ontario, London, Canada.
Abstract
PURPOSE: To develop and evaluate a multiecho phase-unwrapping-based B0 mapping method. METHODS: The proposed method estimates a B0 map by Non-Iterative Correction of phase-Errors (B0-NICE). The B0-NICE method generates an initial B0 map from a "pseudo in-phase" data set by introducing a bias frequency shift to the multipeak fat model, followed by correcting the phase errors using both phase and magnitude information. The performance of the B0-NICE method was evaluated with all data cases from the 2012 ISMRM Challenge. RESULTS: The B0 field estimates from B0-NICE were compared with those generated by GlObally Optimal Surface Estimation (GOOSE). In the presence of large B0 inhomogeneity, the B0-NICE method was able to generate more realistic B0 maps from multiecho data, compared with GOOSE. Accurate estimation of fat-fraction (FF) map was also achieved using the proposed algorithm. CONCLUSION: The primary finding of the present study is that accurate FF and B0 maps are achievable if magnitude data is processed independently and used to correct phase errors existing in B0 maps generated by phase unwrapping. The B0-NICE software is freely available to the scientific community.
PURPOSE: To develop and evaluate a multiecho phase-unwrapping-based B0 mapping method. METHODS: The proposed method estimates a B0 map by Non-Iterative Correction of phase-Errors (B0-NICE). The B0-NICE method generates an initial B0 map from a "pseudo in-phase" data set by introducing a bias frequency shift to the multipeak fat model, followed by correcting the phase errors using both phase and magnitude information. The performance of the B0-NICE method was evaluated with all data cases from the 2012 ISMRM Challenge. RESULTS: The B0 field estimates from B0-NICE were compared with those generated by GlObally Optimal Surface Estimation (GOOSE). In the presence of large B0 inhomogeneity, the B0-NICE method was able to generate more realistic B0 maps from multiecho data, compared with GOOSE. Accurate estimation of fat-fraction (FF) map was also achieved using the proposed algorithm. CONCLUSION: The primary finding of the present study is that accurate FF and B0 maps are achievable if magnitude data is processed independently and used to correct phase errors existing in B0 maps generated by phase unwrapping. The B0-NICE software is freely available to the scientific community.
Authors: Thomas Benkert; John P Mugler; David S Rigie; Daniel K Sodickson; Hersh Chandarana; Kai Tobias Block Journal: Magn Reson Med Date: 2018-04-15 Impact factor: 4.668
Authors: Maximilian N Diefenbach; Stefan Ruschke; Holger Eggers; Jakob Meineke; Ernst J Rummeny; Dimitrios C Karampinos Journal: Magn Reson Med Date: 2018-02-09 Impact factor: 4.668