Evaluation of a new ultrasmall superparamagnetic iron oxide contrast agent Clariscan, (NC100150) for MRI of renal perfusion: experimental study in an animal model.
OBJECTIVE
To determine the diagnostic value of a new ultrasmall superparamagnetic iron oxide Clariscan, (NC100150) for the evaluation of renal perfusion in an animal model using a 3D-FFE-EPI sequence.


METHODS
Four groups of four rabbits each were imaged after bolus injection of NC100150, using a 1.5 T MR system (Gyroscan ACS-NT). T2*w MR images in the coronal plane were acquired over 60 seconds with an echo-shifted 3D-FFE-EPI sequence (TR/TE/alpha = 18/25 msec/8 degrees ). Data were transferred to a workstation and converted into concentration curves. Based on the fitted concentration time curves, parameter maps were calculated pixelwise: bolus arrival time (T0), time-to-peak (TTP), mean transit time (MTT), and relative bolus volume (rBV). Maximum signal decrease was determined with respect to the baseline value.


RESULTS
Mean MTT increased from 4.2 seconds at a dose of 0.25 mg to 5.9 seconds at 1.0 mg (P < .0001). The maximum signal decrease was observed at 0.75 mg, corresponding to 85% of the baseline value. Transit times of the contrast bolus were accurately calculated for the cortex and the outer medulla, but at the level of the inner medulla no arterial flow profile was identified. No significant difference between the cortex and the outer medulla was found for either T0 or rBV, but medullar TTP and MTT were prolonged with regard to cortical TTP and MTT (6.3 seconds vs. 5.7 seconds, P < .001; 5.7 seconds vs. 4.2 seconds, P < .0001).


CONCLUSIONS
The employed intravascular contrast agent is well suited to assess renal perfusion. By the use of a T2*w3D perfusion sequence, cortical and medullar transit times can be quantified and physiologic information on regional perfusion differences can be obtained.
Department of Radiology, University of Muenster, Muenster, Germany. r.bachmann@uni-muenster.de
Rainald
R
Bachmann
Rudolf
R
Conrad
Burkhard
B
Kreft
Oliver
O
Luzar
Wolfgang
W
Block
Sebastian
S
Flacke
Dirk
D
Pauleit
Frank
F
Träber
Jürgen
J
Gieseke
Karin
K
Saebo
Hans
H
Schild
D000818:Animals; D003287:Contrast Media / Q000493:pharmacokinetics*; D003911:Dextrans; D052203:Ferrosoferric Oxide; D007501:Iron / Q000493:pharmacokinetics*; D008099:Liver / Q000098:blood supply*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D058185:Magnetite Nanoparticles; D010087:Oxides / Q000493:pharmacokinetics*; D011817:Rabbits; D018709:Statistics, Nonparametric
D003287:Contrast Media; D003911:Dextrans; D058185:Magnetite Nanoparticles; D010087:Oxides; C097921:ferumoxtran-10; D007501:Iron; D052203:Ferrosoferric Oxide