Arabinogalactan-coated superparamagnetic iron oxide: effect of particle size in liver MRI.
OBJECTIVE
We evaluated the effect of particle size on MR contrast-enhancing properties of arabinogalactan-coated superparamagnetic iron oxide (AG-SPIO) in tumor-bearing rats.


METHODS
T2*-weighted gradient-recalled echo MR studies were performed on rats with surgically implanted liver tumors before and after AG-SPIO administration. Contrast-to-noise ratio (CNR) and percent contrast enhancement (PCE) were calculated for animals given small (15.7 +/- 9.5 nm: n = 6), medium (49.1 +/- 19.7 nm; n = 4), and large (86.9 +/- 27.5 nm; n = 4) particles intravenously (10 mumol Fe/kg).


RESULTS
Postcontrast CNRs were 15.8 +/- 6.9, 8.9 +/- 4.1, and 10.0 +/- 1.8 for small, medium, and large particle groups, respectively. The PCE was -60.0 +/- 3.3, -75.5 +/- 7.9, and -80.5 +/- 1.2%. There was a significant difference in preversus postcontrast CNR for all particle sizes (p < 0.001) and in PCE for small particles as compared with the two larger sizes (p < 0.001). There was no between-group statistical difference in postcontrast CNR for any particle size.


CONCLUSIONS
Larger AG-SPIO particles slightly improve liver contrast enhancement, but have no significant effect on hepatic lesion detection as assessed by CNR.
Wisner
E R
ER
Department of Radiology, School of Medicine, University of California, Davis 95817.
Amparo
E G
EG
Vera
D R
DR
Brock
J M
JM
Barlow
T W
TW
Griffey
S M
SM
Drake
C
C
Katzberg
R W
RW
D000818:Animals; D003287:Contrast Media; D005260:Female; D052203:Ferrosoferric Oxide; D005685:Galactans; D007501:Iron; D008099:Liver / Q000473:pathology*; D008114:Liver Neoplasms, Experimental / Q000175:diagnosis; D008279:Magnetic Resonance Imaging; D010087:Oxides; D051381:Rats; D011916:Rats, Inbred F344
D003287:Contrast Media; D005685:Galactans; D010087:Oxides; D007501:Iron; C005653:arabinogalactan; D052203:Ferrosoferric Oxide