Dosage determination of ultrasmall particles of iron oxide for the delineation of microvasculature in the Wistar rat brain.
OBJECTIVE
This investigation sought to optimize ultrasmall particles of iron oxide (USPIO) contrast agent dosage for visualizing cerebral microvasculature on an 8.0-Tesla ultra high field magnetic resonance imaging system.


METHODS
USPIO contrast agent was intravenously administered to 3 groups of 4 rats at 1, 2, and 3 mg Fe/kg. Each animal was scanned before and after injection of USPIO using a high resolution T2*-weighted gradient recalled echo sequence with an in-plane resolution of 78 microm. The signal-to-noise ratio (SNR) and the number of microvessels visualized within the cortex and basal ganglia were calculated and compared before and after the administration of USPIO.


RESULTS
As the USPIO dose increased, microvascular conspicuity increased, and SNR decreased. A dosage of 2 mg Fe/kg improved microvascular visualization in both cortex and basal ganglion regions relative to 1 mg Fe/kg without significantly sacrificing SNR as was the case at 3 mg Fe/kg.


CONCLUSIONS
Two mg Fe/kg USPIO is an optimal dose when imaging normal rat cerebral microvasculature using GRE T2*-weighted MR imaging at a field strength of 8 T.
Yang
Ming
M
Department of Radiology, College of Medicine and Public Health, The Ohio State University, Columbus, Ohio 43210, USA.
Christoforidis
Gregory A
GA
Figueredo
Tatiana
T
Heverhagen
Johannes T
JT
Abduljalil
Amir
A
Knopp
Michael V
MV
D000818:Animals; D001921:Brain / Q000098:blood supply* / Q000166:cytology*; D002560:Cerebrovascular Circulation; D003287:Contrast Media / Q000008:administration & dosage*; D003911:Dextrans; D004305:Dose-Response Relationship, Drug; D052203:Ferrosoferric Oxide; D007501:Iron / Q000008:administration & dosage*; D008279:Magnetic Resonance Imaging; D058185:Magnetite Nanoparticles; D008297:Male; D008833:Microcirculation / Q000166:cytology*; D010087:Oxides / Q000008:administration & dosage*; D051381:Rats; D017208:Rats, Wistar; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
D003287:Contrast Media; D003911:Dextrans; D058185:Magnetite Nanoparticles; D010087:Oxides; C097921:ferumoxtran-10; D007501:Iron; D052203:Ferrosoferric Oxide