USPIO (Ferumoxtran-10)-enhanced MRI to visualize reticuloendothelial system cells in neonatal rats: feasibility and biodistribution study.
OBJECTIVE
To investigate whether USPIO-enhanced magnetic resonance imaging (MRI) detected reticuloendothelial system (RES) cells in newborn normal rats.


METHODS
Newborn normal rats were imaged in vivo on a 1.5 T MR system, 2-96 hours after intraperitoneal Ferumoxtran-10 (n = 38) or saline injection (control group, n = 5). Signals from liver, spleen, and vertebral bone marrow were measured (T2-weighted Turbo Spin Echo) to describe the kinetics of enhancement. The pups were sacrificed and iron concentrations in plasma and peritoneal fluid were measured using atomic absorption spectrometry. Prussian blue-labeled cells density in liver, spleen, and vertebral bone marrow was assessed.


RESULTS
Significant (P < 0.05) negative enhancement of the liver, spleen, and vertebral bone marrow was noted after Ferumoxtran-10 injection (2-96 hours for liver and spleen, 4-96 hours for bone marrow). Ferumoxtran-10 was absorbed from the peritoneum in the first 8 hours postinjection, entering the circulation with a plasma peak (8 hours); then Ferumoxtran-10 returned over the baseline in plasma (96 hours). Important intracellular iron deposition in liver and spleen was measured postinjection (3-96 hours, P < 0.05). Limited but significant intracellular iron deposition was noted in vertebral bone marrow postinjection (96 hours, P < 0.05), suggesting that Ferumoxtran-10 selectively labeled RES cells after 96 hours and produced nonspecific labeling at earlier timepoints.


CONCLUSIONS
Ferumoxtran-10-enhanced MRI visualizes RES cells in vivo in newborn rats.
Azoulay
Robin
R
Pediatric Imaging Department, Robert Debré Hospital, Assistance Publique-Hôpitaux de Paris, Paris, France. robin.azoulay@rdb.aphp.fr
Olivier
Paul
P
Baud
Olivier
O
Verney
Catherine
C
Santus
Robin
R
Robert
Philippe
P
Gressens
Pierre
P
Sebag
Guy
G
D000818:Animals; D000831:Animals, Newborn; D001853:Bone Marrow / Q000378:metabolism; D003287:Contrast Media / Q000493:pharmacokinetics; D003911:Dextrans; D005240:Feasibility Studies; D052203:Ferrosoferric Oxide; D007501:Iron / Q000493:pharmacokinetics*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D058185:Magnetite Nanoparticles; D012157:Mononuclear Phagocyte System / Q000166:cytology*; D010087:Oxides / Q000493:pharmacokinetics*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013154:Spleen / Q000378:metabolism; D018709:Statistics, Nonparametric; D014018:Tissue Distribution
D003287:Contrast Media; D003911:Dextrans; D058185:Magnetite Nanoparticles; D010087:Oxides; C097921:ferumoxtran-10; D007501:Iron; D052203:Ferrosoferric Oxide