Background field removal technique using regularization enabled sophisticated harmonic artifact reduction for phase data with varying kernel sizes.
An effective background field removal technique is desired for more accurate quantitative susceptibility mapping (QSM) prior to dipole inversion. The aim of this study was to evaluate the accuracy of regularization enabled sophisticated harmonic artifact reduction for phase data with varying spherical kernel sizes (REV-SHARP) method using a three-dimensional head phantom and human brain data. The proposed REV-SHARP method used the spherical mean value operation and Tikhonov regularization in the deconvolution process, with varying 2-14mm kernel sizes. The kernel sizes were gradually reduced, similar to the SHARP with varying spherical kernel (VSHARP) method. We determined the relative errors and relationships between the true local field and estimated local field in REV-SHARP, VSHARP, projection onto dipole fields (PDF), and regularization enabled SHARP (RESHARP). Human experiment was also conducted using REV-SHARP, VSHARP, PDF, and RESHARP. The relative errors in the numerical phantom study were 0.386, 0.448, 0.838, and 0.452 for REV-SHARP, VSHARP, PDF, and RESHARP. REV-SHARP result exhibited the highest correlation between the true local field and estimated local field. The linear regression slopes were 1.005, 1.124, 0.988, and 0.536 for REV-SHARP, VSHARP, PDF, and RESHARP in regions of interest on the three-dimensional head phantom. In human experiments, no obvious errors due to artifacts were present in REV-SHARP. The proposed REV-SHARP is a new method combined with variable spherical kernel size and Tikhonov regularization. This technique might make it possible to be more accurate backgroud field removal and help to achive better accuracy of QSM.
Department of Radiology, Nagoya City University Hospital, 1-Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya City, Aichi, 4678602, Japan. Electronic address: h.kan1208@gmail.com.
Hirohito
H
Kan
Department of Radiology, Nagoya City University Hospital, 1-Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya City, Aichi, 4678602, Japan. Electronic address: hhkasai@gmail.com.
Harumasa
H
Kasai
Department of Radiology, Nagoya City University Hospital, 1-Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya City, Aichi, 4678602, Japan. Electronic address: rarai51@med.nagoya-cu.ac.jp.
Nobuyuki
N
Arai
Department of Radiology, Nagoya City University Hospital, 1-Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya City, Aichi, 4678602, Japan. Electronic address: rakunny@med.nagoya-cu.ac.jp.
Hiroshi
H
Kunitomo
Department of Radiology, Nagoya City University Hospital, 1-Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya City, Aichi, 4678602, Japan. Electronic address: rahirose@med.nagoya-cu.ac.jp.
Yasujiro
Y
Hirose
Department of Radiology, Nagoya City University Hospital, 1-Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya City, Aichi, 4678602, Japan. Electronic address: yshiba@med.nagoya-cu.ac.jp.
Yuta
Y
Shibamoto
D000328:Adult; D000465:Algorithms; D016477:Artifacts; D001921:Brain / Q000000981:diagnostic imaging*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods*; D019047:Phantoms, Imaging; D012016:Reference Values; D015203:Reproducibility of Results
Background field removal; Quantitative susceptibility mapping (QSM); Regularization enabled sophisticated harmonic artifact reduction for phase data with varying kernel sizes (REV-SHARP) Sophisticated harmonic artifact reduction for phase data (SHARP)