Abstract #3936
            Regional and state-dependent properties of M for high-field calibrated fMRI in rat brain
                      Christina Y. Shu                     1                    , Daniel Coman                     2                    , 						Basavaraju G. Sanganahalli                     2                    , Helen Wang                     2                    , 						Christoph Juchem                     2                    , Peter Herman                     2                    , 						and Fahmeed Hyder                     1,2          
            
            1
           
           Biomedical Engineering, Yale University, New 
						Haven, CT, United States,
           
            2
           
           Diagnostic 
						Radiology, Yale University, CT, United States
          
            
          In calibrated fMRI the BOLD signal range from 
						deoxyhemoglobin to oxyhemoglobin is reflected by M. 
						Since blood oxygenation changes are captured with 
						relaxation rates by gradient echo (R2*) and spin echo 
						(R2), M is echo time multiplied by R2 (i.e., R2*- R2). 
						Because it is unclear if the M range reported in 
						calibrated fMRI studies is due to regional/state 
						differences, we tested M estimated from R2 in rat 
						brain. Homogenous M values were found in the cortex 
						regardless of the brain state. These results suggest 
						that a direct R2 mapping method may provide more 
						accurate M values for calibrated fMRI.
         
				
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