From Expected Propagator Distribution to Optimal Q-space Sample Metric

  • Hans Knutsson
  • Carl-Fredrik Westin
Part of the Lecture Notes in Computer Science book series (LNCS, volume 8675)


We present a novel approach to determine a local q-space metric that is optimal from an information theoretic perspective with respect to the expected signal statistics. It should be noted that the approach does not attempt to optimize the quality of a pre-defined mathematical representation, the estimator. In contrast, our suggestion aims at obtaining the maximum amount of information without enforcing a particular feature representation.

Results for three significantly different average propagator distributions are presented. The results show that the optimal q-space metric has a strong dependence on the assumed distribution in the targeted tissue. In many practical cases educated guesses can be made regarding the average propagator distribution present. In such cases the presented analysis can produce a metric that is optimal with respect to this distribution. The metric will be different at different q-space locations and is defined by the amount of additional information that is obtained when adding a second sample at a given offset from a first sample. The intention is to use the obtained metric as a guide for the generation of specific efficient q-space sample distributions for the targeted tissue.


Information Gain Axis Ratio Angular Direction Propagator Distribution Information Theoretic Perspective 
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Copyright information

© Springer International Publishing Switzerland 2014

Authors and Affiliations

  • Hans Knutsson
    • 1
  • Carl-Fredrik Westin
    • 2
  1. 1.Linköping UniversitySweden
  2. 2.Harvard Medical SchoolUSA

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