Abstract #1808
             Phase susceptibility-weighted imaging of SPIO nanoparticles
             Xie J,  Li K,  Fung S,  Kotys M
             National Institutes of Health
             Molecular imaging of superparamagnetic iron oxide nanoparticles (SPIONs) is an effective method for cell tracking using magnetic resonance imaging (MRI).  A new phase-based (&[Delta]&[phi]) technique for susceptibility-weighted imaging (SWI) of SPIONs is presented and compared to magnitude-based SWI methods for sensitivity and relation to iron concentration and signal-to-noise ratio (SNR).  R2* appeared non-linear to iron concentration, while &[Delta]&[phi]appears appeared linear.  The SNR for the &[Delta]&[phi]method increased from 3.2 to 80 times that of the R2* method as concentration increased.  Phase-based SWI of SPIONs appears to be linear to concentration of iron and has higher SNR than magnitude-based SWI methods.