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N3 Bias Field Correction Explained as a Bayesian Modeling Method

Larsen CT, Eugenio Iglesias J and Van Leemput K

2014

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Abstract. Although N3 is perhaps the most widely used method forMRI bias field correction, its underlying mechanism is in fact not wellunderstood. Specifically, the method relies on a relatively heuristic recipeof alternating iterative steps that does not optimize any particular objectivefunction. In this paper we explain the successful bias field correctionproperties of N3 by showing that it implicitly uses the same generativemodels and computational strategies as expectation maximization (EM)based bias field correction methods.We demonstrate experimentally thatpurely EM-based methods are capable of producing bias field correctionresults comparable to those of N3 in less computation time.
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