Mitigating undersampling errors in MR fingerprinting by sequence optimization

Magnetic Resonance in Medicine, vol. 89, pp. 2076–2087

Abstract

Purpose To develop a method for MR Fingerprinting (MRF) sequence optimization that takes both the applied undersampling pattern and a realistic reference map into account. Methods A predictive model for the undersampling error leveraging on perturbation theory was exploited to optimize the MRF flip angle sequence for improved robustness against undersampling artifacts. In this framework parameter maps from a previously acquired MRF scan were used as reference. Sequences were optimized for different sequence lengths, smoothness constraints and undersampling factors. Numerical simulations and in vivo measurements in eight healthy subjects were performed to assess the effect of the performed optimization. The optimized MRF sequences were compared to a conventionally shaped flip angle pattern and an optimized pattern based on the Cramér–Rao lower bound (CRB). Results Numerical simulations and in vivo results demonstrate that the undersampling errors can be suppressed by flip angle optimization. Analysis of the in vivo results show that a sequence optimized for improved robustness against undersampling with a flip angle train of length 400 yielded significantly lower median absolute errors in : and : compared to the conventional (: , : ) and CRB‐based (: , : ) sequences. Conclusion The proposed method is able to optimize the MRF flip angle pattern such that significant mitigation of the artifacts from strong k‐space undersampling in MRF is achieved.

Authors 6

1. David Heesterbeek corresponding

   Delft University of Technology

   Affiliation as printed

   Delft Institute of Applied Mathematics Delft University of Technology Delft The Netherlands

   Department of Imaging Physics Delft University of Technology Delft The Netherlands

   Delft Institute of Applied Mathematics, Delft University of Technology, Delft, The Netherlands

   Department of Imaging Physics, Delft University of Technology, Delft, The Netherlands

2. Kirsten Koolstra Aachen

   Leiden University Medical Center

   Affiliation as printed

   LKEB of the Department of Radiology Leiden University Medical Center Leiden The Netherlands

   LKEB of the Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands

3. Matthias J.P. van Osch Aachen

   Leiden University Medical Center

   Affiliation as printed

   C.J. Gorter MRI center of the Department of Radiology Leiden University Medical Center Leiden The Netherlands

   C.J. Gorter MRI center of the Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands

4. Martin B. van Gijzen

   Delft University of Technology

   Affiliation as printed

   Delft Institute of Applied Mathematics Delft University of Technology Delft The Netherlands

   Delft Institute of Applied Mathematics, Delft University of Technology, Delft, The Netherlands

5. Franciscus M. Vos

   Erasmus MC · Delft University of Technology

   Affiliation as printed

   Department of Imaging Physics Delft University of Technology Delft The Netherlands

   Department of Radiology Erasmus University Medical Center Rotterdam The Netherlands

   Department of Imaging Physics, Delft University of Technology, Delft, The Netherlands

   Department of Radiology, Erasmus University Medical Center, Rotterdam, The Netherlands

6. Martijn A. Nagtegaal Aachen

   Leiden University Medical Center · Delft University of Technology

   Affiliation as printed

   C.J. Gorter MRI center of the Department of Radiology Leiden University Medical Center Leiden The Netherlands

   Department of Imaging Physics Delft University of Technology Delft The Netherlands

   C.J. Gorter MRI center of the Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands

   Department of Imaging Physics, Delft University of Technology, Delft, The Netherlands