TY  - JOUR
AU  - Huang, Xiaolei
AU  - Dong, Hui
AU  - Qiu, Yang
AU  - Li, Bo
AU  - Tao, Quan
AU  - Zhang, Yi
AU  - Krause, Hans-Joachim
AU  - Offenhäusser, Andreas
AU  - Xie, Xiaoming
TI  - Adaptive suppression of power line interference in ultra-low field magnetic resonance imaging in an unshielded environment
JO  - Journal of magnetic resonance
VL  - 286
SN  - 1090-7807
CY  - Amsterdam [u.a.]
PB  - Elsevier
M1  - FZJ-2017-07781
SP  - 52 - 59
PY  - 2018
AB  - Power-line harmonic interference and fixed-frequency noise peaks may cause stripe-artifacts in ultra-low field (ULF) magnetic resonance imaging (MRI) in an unshielded environment and in a conductively shielded room. In this paper we describe an adaptive suppression method to eliminate these artifacts in MRI images. This technique utilizes spatial correlation of the interference from different positions, and is realized by subtracting the outputs of the reference channel(s) from those of the signal channel (s) using wavelet analysis and the least squares method. The adaptive suppression method is first implemented to remove the image artifacts in simulation. We then experimentally demonstrate the feasibility of this technique by adding three orthogonal superconducting quantum interference device (SQUID) magnetometers as reference channels to compensate the output of one 2nd-order gradiometer. The experimental results show great improvement in the imaging quality in both 1D and 2D MRI images at two common imaging frequencies, 1.3 kHz and 4.8 kHz. At both frequencies, the effective compensation bandwidth is as high as 2 kHz. Furthermore, we examine the longitudinal relaxation times of the same sample before and after compensation, and show that the MRI properties of the sample did not change after applying adaptive suppression. This technique can effectively increase the imaging bandwidth and be applied to ULF MRI detected by either SQUIDs or Faraday coil in both an unshielded environment and a conductively shielded room.
LB  - PUB:(DE-HGF)16
C6  - pmid:29183004
UR  - <Go to ISI:>//WOS:000424071300008
DO  - DOI:10.1016/j.jmr.2017.11.009
UR  - https://juser.fz-juelich.de/record/840227
ER  -