title: Adapted random sampling patterns for accelerated MRI.
abstract: OBJECTIVE
  Variable density random sampling patterns have recently become increasingly popular for accelerated imaging strategies, as they lead to incoherent aliasing artifacts. However, the design of these sampling patterns is still an open problem. Current strategies use model assumptions like polynomials of different order to generate a probability density function that is then used to generate the sampling pattern. This approach relies on the optimization of design parameters which is very time consuming and therefore impractical for daily clinical use.
  
  
  METHODS
  This work presents a new approach that generates sampling patterns by making use of power spectra of existing reference data sets and hence requires neither parameter tuning nor an a priori mathematical model of the density of sampling points.
  
  
  RESULTS
  The approach is validated with downsampling experiments, as well as with accelerated in vivo measurements. The proposed approach is compared with established sampling patterns, and the generalization potential is tested by using a range of reference images. Quantitative evaluation is performed for the downsampling experiments using RMS differences to the original, fully sampled data set.
  
  
  CONCLUSIONS
  Our results demonstrate that the image quality of the method presented in this paper is comparable to that of an established model-based strategy when optimization of the model parameter is carried out and yields superior results to non-optimized model parameters. However, no random sampling pattern showed superior performance when compared to conventional Cartesian subsampling for the considered reconstruction strategy.
authors.affiliation: Institute of Medical Engineering, Graz University of Technology, Kronesgasse 5, 8010 Graz, Austria. florian.knoll@tugraz.at
authors.forename: Florian
authors.initials: F
authors.lastname: Knoll
authors.forename: Christian
authors.initials: C
authors.lastname: Clason
authors.forename: Clemens
authors.initials: C
authors.lastname: Diwoky
authors.forename: Rudolf
authors.initials: R
authors.lastname: Stollberger
mesh_terms: D003627:Data Interpretation, Statistical; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods*; D010363:Pattern Recognition, Automated / Q000379:methods*; D011336:Probability; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity