Jan Ole Pedersen1,2,3, Christian G Hanson4, Rong Xue5,6, Lars G Hanson7,8. 1. Department of Health Technology, Center for Magnetic Resonance, Technical University of Denmark, Kongens Lyngby, Denmark. 2. Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital, Hvidovre, Denmark. 3. Sino-Danish Center for Education and Research, Aarhus, Denmark. 4. , Køge, Denmark. 5. State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China. 6. Sino-Danish College, University of Chinese Academy of Sciences, Beijing, China. 7. Department of Health Technology, Center for Magnetic Resonance, Technical University of Denmark, Kongens Lyngby, Denmark. lghan@dtu.dk. 8. Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital, Hvidovre, Denmark. lghan@dtu.dk.
Abstract
OBJECTIVES: The objective of this study was to concurrently acquire an inductive k-space trajectory measure and corresponding imaging data by an MR scanner. MATERIALS AND METHODS: 1D gradient measures were obtained by digital integration, regularized using measured gradient coil currents and recorded individually by the scanner concurrently with raw MR data. Gradient measures were frequency modulated into an RF signal receivable by the scanner, yielding a k-space trajectory measure from the cumulative phase of the acquired data. Generation of the gradient measure and frequency modulation was performed by previously developed custom, versatile circuitry. RESULTS: For a normal echo planar imaging (EPI) sequence, the acquired k-space trajectory measure yielded slightly improved image quality compared to that obtained from using the scanner's estimated eddy current-compensated k-space trajectory. For a spiral trajectory, the regularized inductive k-space trajectory measure lead to a 76% decrease in the root-mean-square error of the reconstructed image. DISCUSSION: While the proof-of-concept experiments show potential for further improvement, the feasibility of inductively measuring k-space trajectories and increasing the precision through regularization was demonstrated. The approach may offer an inexpensive method to acquire k-space trajectories concurrently with scanning.
OBJECTIVES: The objective of this study was to concurrently acquire an inductive k-space trajectory measure and corresponding imaging data by an MR scanner. MATERIALS AND METHODS: 1D gradient measures were obtained by digital integration, regularized using measured gradient coil currents and recorded individually by the scanner concurrently with raw MR data. Gradient measures were frequency modulated into an RF signal receivable by the scanner, yielding a k-space trajectory measure from the cumulative phase of the acquired data. Generation of the gradient measure and frequency modulation was performed by previously developed custom, versatile circuitry. RESULTS: For a normal echo planar imaging (EPI) sequence, the acquired k-space trajectory measure yielded slightly improved image quality compared to that obtained from using the scanner's estimated eddy current-compensated k-space trajectory. For a spiral trajectory, the regularized inductive k-space trajectory measure lead to a 76% decrease in the root-mean-square error of the reconstructed image. DISCUSSION: While the proof-of-concept experiments show potential for further improvement, the feasibility of inductively measuring k-space trajectories and increasing the precision through regularization was demonstrated. The approach may offer an inexpensive method to acquire k-space trajectories concurrently with scanning.
Keywords:
Encoding of signals in MRI raw data; Gradient imperfections; Inductive measurement of k-space trajectories; Magnetic resonance imaging; Regularization by current measure
Authors: Bénédicte M A Delattre; Robin M Heidemann; Lindsey A Crowe; Jean-Paul Vallée; Jean-Noël Hyacinthe Journal: Magn Reson Imaging Date: 2010-04-21 Impact factor: 2.546
Authors: David O Brunner; Benjamin E Dietrich; Mustafa Çavuşoğlu; Bertram J Wilm; Thomas Schmid; Simon Gross; Christoph Barmet; Klaas P Pruessmann Journal: NMR Biomed Date: 2015-08-13 Impact factor: 4.044
Authors: Mads Andersen; Lars G Hanson; Kristoffer H Madsen; Joep Wezel; Vincent Boer; Tijl van der Velden; Matthias J P van Osch; Dennis Klomp; Andrew G Webb; Maarten J Versluis Journal: Magn Reson Med Date: 2015-06-15 Impact factor: 4.668
Authors: Lars Kasper; Saskia Bollmann; S Johanna Vannesjo; Simon Gross; Maximilian Haeberlin; Benjamin E Dietrich; Klaas P Pruessmann Journal: Magn Reson Med Date: 2014-08-14 Impact factor: 4.668