Overhauser-enhanced MR imaging (OMRI).
OBJECTIVE
To evaluate a new single-electron contrast agent for Overhauser-enhanced MR imaging. The contrast agents that are currently available give enhancement factors that are too low to make the technique a valid option for routine clinical use.


METHODS
MR images were generated directly following the injection of the substance into rats. The MR scanner was operated at a main magnetic field of 0.01 T and equipped with a separate rf-transmitter tuned to the electron paramagnetic resonance frequency of the contrast agent.


RESULTS
As expected, the images generated show a high level of enhancement in areas where the contrast agent was present, and a maximum enhancement of 60 times the normal proton signal was obtained in the vascular area. The signal-to-noise ratios in the images were superior to those previously attained.


CONCLUSIONS
The new contrast agent makes it possible to generate MR images with both morphological and functional information at 0.01 T. The signal-to-noise ratios found in the generated images were of the same order as, or better than, those obtained with the standard clinical routine.
Golman
K
K
Nycomed Innovation AB, Malmö, Sweden.
Leunbach
I
I
Ardenkjaer-Larsen
J H
JH
Ehnholm
G J
GJ
Wistrand
L G
LG
Petersson
J S
JS
Järvi
A
A
Vahasalo
S
S
D000818:Animals; D001812:Blood-Brain Barrier; D001921:Brain / Q000033:anatomy & histology / Q000378:metabolism; D003287:Contrast Media / Q000008:administration & dosage* / Q000493:pharmacokinetics; D005290:Ferric Compounds / Q000008:administration & dosage / Q000493:pharmacokinetics; D019786:Gadolinium DTPA / Q000008:administration & dosage / Q000493:pharmacokinetics; D007089:Image Enhancement / Q000379:methods*; D007275:Injections, Intravenous; D007501:Iron / Q000008:administration & dosage / Q000493:pharmacokinetics; D007668:Kidney / Q000033:anatomy & histology / Q000378:metabolism; D008099:Liver / Q000033:anatomy & histology / Q000378:metabolism; D008279:Magnetic Resonance Imaging; D008297:Male; D010087:Oxides / Q000008:administration & dosage / Q000493:pharmacokinetics; D010100:Oxygen / Q000378:metabolism*; D010101:Oxygen Consumption; D051381:Rats; D017208:Rats, Wistar; D012680:Sensitivity and Specificity; D013113:Spin Labels
D003287:Contrast Media; D005290:Ferric Compounds; D010087:Oxides; C069727:Sonazoid; D013113:Spin Labels; C064925:gadodiamide; D007501:Iron; D019786:Gadolinium DTPA; D010100:Oxygen