Identifying inflamed carotid plaques using in vivo USPIO-enhanced MR imaging to label plaque macrophages.
BACKGROUND
Inflammation within atherosclerotic lesions contributes to plaque instability and vulnerability to rupture. We set out to evaluate the use of a macrophage labeling agent to identify carotid plaque inflammation by in vivo magnetic resonance imaging (MRI).


RESULTS
Thirty patients with symptomatic severe carotid stenosis scheduled for carotid endarterectomy underwent multi-sequence MRI of the carotid bifurcation before and after injection of ultrasmall superparamagnetic particles of iron oxide (USPIOs). USPIO particles accumulated in macrophages in 24 of 30 plaques (80%). Areas of signal intensity reduction, corresponding to USPIO/macrophage-positive histological sections, were visualized in 24 of 27 (89%) patients, with an average reduction in signal intensity induced by the USPIO particles of 24% (range, 3.1% to 60.8%).


CONCLUSIONS
USPIO-enhanced MRI can identify plaque inflammation in vivo by accumulation of USPIO within macrophages in carotid plaques.
Trivedi
Rikin A
RA
University Department of Radiology, Addenbrooke's Hospital, Cambridge, UK. rt256@radiol.cam.ac.uk
Mallawarachi
Chinthake
C
U-King-Im
Jean-Marie
JM
Graves
Martin J
MJ
Horsley
Jo
J
Goddard
Martin J
MJ
Brown
Andrew
A
Wang
Liqun
L
Kirkpatrick
Peter J
PJ
Brown
John
J
Gillard
Jonathan H
JH
D016893:Carotid Stenosis / Q000175:diagnosis* / Q000378:metabolism / Q000473:pathology; D004396:Coloring Agents / Q000493:pharmacokinetics; D003287:Contrast Media; D003911:Dextrans; D052203:Ferrosoferric Oxide; D006801:Humans; D007089:Image Enhancement; D007091:Image Processing, Computer-Assisted; D007249:Inflammation / Q000175:diagnosis* / Q000378:metabolism / Q000473:pathology; D007501:Iron / Q000493:pharmacokinetics; D008264:Macrophages / Q000378:metabolism / Q000473:pathology; D008279:Magnetic Resonance Imaging; D058185:Magnetite Nanoparticles; D010087:Oxides / Q000493:pharmacokinetics; D013194:Staining and Labeling; D014018:Tissue Distribution
D004396:Coloring Agents; D003287:Contrast Media; D003911:Dextrans; D058185:Magnetite Nanoparticles; D010087:Oxides; C097921:ferumoxtran-10; D007501:Iron; D052203:Ferrosoferric Oxide