Macrophage imaging in central nervous system and in carotid atherosclerotic plaque using ultrasmall superparamagnetic iron oxide in magnetic resonance imaging.
The long blood circulating time and the progressive macrophage uptake in inflammatory tissues of ultrasmall superparamagnetic iron oxide (USPIO) particles are 2 properties of major importance for magnetic resonance imaging (MRI) pathologic tissue characterization. This article reviews the proof of principle of applications such as imaging of carotid atherosclerotic plaque, stroke, brain tumor characterization, or multiple sclerosis. In the human carotid artery, USPIO accumulation in activated macrophages induced a focal drop in signal intensity compared with preinfusion MRI. The USPIO signal alterations observed in ischemic areas of stroke patients is probably related to the visualization of inflammatory macrophage recruitment into human brain infarction since animal experiments in such models demonstrated the internalization of USPIO into the macrophages localized in these areas. In brain tumors, USPIO particles which do not pass the ruptured blood-brain barrier at early times postinjection can be used to assess tumoral microvascular heterogeneity. Twenty-four hours after injection, when the cellular phase of USPIO takes place, the USPIO tumoral contrast enhancement was higher in high-grade than in low-grade tumors. Several experimental studies and a pilot multiple sclerosis clinical trial in 10 patients have shown that USPIO contrast agents can reveal the presence of inflammatory multiple sclerosis lesions. The enhancement with USPIO does not completely overlap with the gadolinium chelate enhancement. While the proof of concept that USPIO can visualize macrophage infiltrations has been confirmed in animals and patients in several applications (carotid atherosclerotic lesions, stroke, brain tumors and multiple sclerosis), larger prospective clinical studies are needed to demonstrate the clinical benefit of using USPIO as an MRI in vivo surrogate marker for brain inflammatory diseases.
Corot
Claire
C
Guerbet Research, BP50400, Roissy CDG France. claire.corot@guerbet-group.com
Petry
Klaus G
KG
Trivedi
Rikin
R
Saleh
Andreas
A
Jonkmanns
Cornelia
C
Le Bas
Jean-François
JF
Blezer
Erwin
E
Rausch
Martin
M
Brochet
Bruno
B
Foster-Gareau
Paula
P
Balériaux
Danièle
D
Gaillard
Sophile
S
Dousset
Vincent
V
D001161:Arteriosclerosis / Q000175:diagnosis* / Q000378:metabolism; D002339:Carotid Arteries / Q000473:pathology*; D002340:Carotid Artery Diseases / Q000175:diagnosis* / Q000378:metabolism; D002490:Central Nervous System / Q000503:physiopathology*; D003287:Contrast Media; D003911:Dextrans; D005290:Ferric Compounds / Q000493:pharmacokinetics*; D052203:Ferrosoferric Oxide; D006801:Humans; D007089:Image Enhancement; D007501:Iron / Q000493:pharmacokinetics*; D008264:Macrophages; D008279:Magnetic Resonance Imaging; D058185:Magnetite Nanoparticles; D010087:Oxides / Q000493:pharmacokinetics*
D003287:Contrast Media; D003911:Dextrans; D005290:Ferric Compounds; D058185:Magnetite Nanoparticles; D010087:Oxides; C097921:ferumoxtran-10; C000499:ferric oxide; D007501:Iron; D052203:Ferrosoferric Oxide