Background field removal technique based on non-regularized variable kernels sophisticated harmonic artifact reduction for phase data for quantitative susceptibility mapping

• Published in: Magnetic resonance imaging Vol. 52; pp. 94 - 101
• Main Authors: Kan, Hirohito, Arai, Nobuyuki, Takizawa, Masahiro, Omori, Kazuyoshi, Kasai, Harumasa, Kunitomo, Hiroshi, Hirose, Yasujiro, Shibamoto, Yuta
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Inc 01.10.2018
• Subjects: Background field removal; Non-regularized variable kernels sophisticated harmonic artifact reduction for phase data; Quantitative susceptibility mapping; Sophisticated harmonic artifact reduction for phase data; Variable kernels sophisticated harmonic artifact reduction for phase data; VSHARP; Background field removal; Variable kernels sophisticated harmonic artifact reduction for phase data; QSM; TSVD; Quantitative susceptibility mapping; CN; FOV; Non-regularized variable kernels sophisticated harmonic artifact reduction for phase data; BET; VOI; PDF; STIMS; TFI; Sophisticated harmonic artifact reduction for phase data; MEDI; SHARP; SMV; COSMOS
• ISSN: 0730-725X; 1873-5894
• DOI: 10.1016/j.mri.2018.06.006

We developed a non-regularized, variable kernel, sophisticated harmonic artifact reduction for phase data (NR-VSHARP) method to accurately estimate local tissue fields without regularization for quantitative susceptibility mapping (QSM). We then used a digital brain phantom to evaluate the accuracy of the NR-VSHARP method, and compared it with the VSHARP and iterative spherical mean value (iSMV) methods through in vivo human brain experiments. Our proposed NR-VSHARP method, which uses variable spherical mean value (SMV) kernels, minimizes L2 norms only within the volume of interest to reduce phase errors and save cortical information without regularization. In a numerical phantom study, relative local field and susceptibility map errors were determined using NR-VSHARP, VSHARP, and iSMV. Additionally, various background field elimination methods were used to image the human brain. In a numerical phantom study, the use of NR-VSHARP considerably reduced the relative local field and susceptibility map errors throughout a digital whole brain phantom, compared with VSHARP and iSMV. In the in vivo experiment, the NR-VSHARP-estimated local field could sufficiently achieve minimal boundary losses and phase error suppression throughout the brain. Moreover, the susceptibility map generated using NR-VSHARP minimized the occurrence of streaking artifacts caused by insufficient background field removal. Our proposed NR-VSHARP method yields minimal boundary losses and highly precise phase data. Our results suggest that this technique may facilitate high-quality QSM.