Abstract #2627
            PERFORMANCE BOUNDS FOR DIFFUSION MRI MODELS OF TISSUE MICROSTRUCTURE
                      Hamed Y. Mesri                     1,2                    , Kelvin J. Layton                     1,3                    , 						Iven M. Y. Mareels                     1                    , and Leigh A. Johnston                     1,3          
            
            1
           
           Department of Electrical and Electronic 
						Engineering, The University of Melbourne, Melbourne, 
						Victoria, Australia,
           
            2
           
           Victoria 
						Research Laboratory, National ICT Australia, Melbourne, 
						Victoria, Australia,
           
            3
           
           Florey 
						Institute of Neuroscience and Mental Health, Melbourne, 
						Victoria, Australia
          
            
          Cramer Rao Lower Bound analysis is used to evaluate two 
						compartment hindered/restricted diffusion models for 
						estimation of mean axon diameter or axon diameter 
						distributions from diffusion weighted MRI data. Our 
						best-case model analysis demonstrates that the models 
						are prone to high uncertainty levels. In practice, 
						experimental data is acquired in regimes far from 
						best-case model assumptions. Thus estimator performance 
						is necessarily worse than the Cramer Rao error rates, 
						which casts doubt on the ability of these models to 
						robustly estimate microstructural features from 
						diffusion MRI data. The Cramer Rao analysis technique is 
						extensible to all parametric model-based inference 
						methods.
         
				
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