In vivo detection of macrophages in human carotid atheroma: temporal dependence of ultrasmall superparamagnetic particles of iron oxide-enhanced MRI.
Background- It has been suggested that inflammatory cells within vulnerable plaques may be visualized by superparamagnetic iron oxide particle-enhanced MRI. The purpose of this study was to determine the time course for macrophage visualization with in vivo contrast-enhanced MRI using an ultrasmall superparamagnetic iron oxide (USPIO) agent in symptomatic human carotid disease.


METHODS
Eight patients scheduled for carotid endarterectomy underwent multisequence MRI of the carotid bifurcation before and 24, 36, 48, and 72 hours after Sinerem (2.6 mg/kg) infusion.


RESULTS
USPIO particles accumulated in macrophages in 7 of 8 patients given Sinerem. Areas of signal intensity reduction, corresponding to USPIO/macrophage-positive histological sections, were visualized in all 7 of these patients, optimally between 24 and 36 hours, decreasing after 48 hours, but still evident up to 96 hours after infusion.


CONCLUSIONS
USPIO-enhanced MRI of carotid atheroma can be used to identify macrophages in vivo. The temporal change in the resultant signal intensity reduction on MRI suggests an optimal time window for the detection of macrophages on postinfusion imaging.
Trivedi
Rikin A
RA
University Department of Radiology, Addenbrooke's Hospital, Cambridge, UK.
U-King-Im
Jean-Marie
JM
Graves
Martin J
MJ
Cross
Justin J
JJ
Horsley
Jo
J
Goddard
Martin J
MJ
Skepper
Jeremy N
JN
Quartey
George
G
Warburton
Elizabeth
E
Joubert
Ilse
I
Wang
Liqun
L
Kirkpatrick
Peter J
PJ
Brown
John
J
Gillard
Jonathan H
JH
D000368:Aged; D001161:Arteriosclerosis / Q000097:blood* / Q000175:diagnosis* / Q000473:pathology; D002339:Carotid Arteries / Q000473:pathology; D016893:Carotid Stenosis / Q000097:blood* / Q000175:diagnosis* / Q000473:pathology; D003287:Contrast Media / Q000008:administration & dosage; D003911:Dextrans; D005260:Female; D052203:Ferrosoferric Oxide; D006801:Humans; D007501:Iron; D008264:Macrophages / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D058185:Magnetite Nanoparticles; D008297:Male; D008875:Middle Aged; D010087:Oxides
D003287:Contrast Media; D003911:Dextrans; D058185:Magnetite Nanoparticles; D010087:Oxides; C097921:ferumoxtran-10; D007501:Iron; D052203:Ferrosoferric Oxide