Ferumoxtran-10-enhanced MRI of the hypercholesterolemic rabbit aorta: relationship between signal loss and macrophage infiltration.
OBJECTIVE
Ferumoxtran-10 is an MRI contrast agent, which accumulates in macrophages and induces magnetic susceptibility artifacts (MSAs). We evaluated the ability of ferumoxtran-10-enhanced MRI to quantify focal macrophage infiltration in the aortic wall of hypercholesterolemic rabbits.


RESULTS
Six weeks after a double-balloon injury of the infrarenal aorta, 12 hypercholesterolemic rabbits underwent MRI of the aorta before (first MRI) and after (second MRI) intravenous injection of ferumoxtran-10 (n=10) or saline (n=2). A third MRI was performed 5 days later to detect ferumoxtran-10-induced MSA in the aortic wall. Aortas were subsequently processed for histology, immunohistochemistry, and gelatin zymography studies. Injured aortas displayed a macrophage-rich neointima with high-matrix metalloproteinase 2 and 9 activities. Iron stain of injured aortas showed massive accumulation of ferumoxtran-10 in neointimal macrophages. Five days after the injection of ferumoxtran-10, MSAs were detected only in the injured aortas by in vivo MRI and were quantified indirectly using the percentage reduction of luminal area attributable to the extension of these MSAs in the aortic lumen. This parameter correlated with macrophage infiltration on corresponding aortic cross-sections (r=0.82; P<0.05).


CONCLUSIONS
Ferumoxtran-10-enhanced MRI allows quantitative assessment of macrophage infiltration induced by balloon angioplasty in the aorta of hypercholesterolemic rabbits.
Hyafil
Fabien
F
INSERM U698, Hôpital Bichat, Assistance Publique-Hôpitaux de Paris, Paris, France.
Laissy
Jean-Pierre
JP
Mazighi
Mikael
M
Tchétché
Didier
D
Louedec
Liliane
L
Adle-Biassette
Homa
H
Chillon
Sylvie
S
Henin
Dominique
D
Jacob
Marie-Paule
MP
Letourneur
Didier
D
Feldman
Laurent J
LJ
D000818:Animals; D001011:Aorta / Q000276:immunology / Q000293:injuries / Q000473:pathology; D002404:Catheterization / Q000009:adverse effects*; D017364:Collagenases / Q000378:metabolism; D003287:Contrast Media / Q000494:pharmacology*; D003911:Dextrans; D004792:Enzyme Precursors / Q000378:metabolism; D052203:Ferrosoferric Oxide; D018093:Gelatinases / Q000378:metabolism; D006937:Hypercholesterolemia / Q000276:immunology / Q000473:pathology*; D007501:Iron / Q000494:pharmacology*; D008264:Macrophages / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D058185:Magnetite Nanoparticles; D008297:Male; D020780:Matrix Metalloproteinase 9; D008666:Metalloendopeptidases / Q000378:metabolism; D010087:Oxides / Q000494:pharmacology*; D011817:Rabbits; D014657:Vasculitis / Q000276:immunology / Q000473:pathology
D003287:Contrast Media; D003911:Dextrans; D004792:Enzyme Precursors; D058185:Magnetite Nanoparticles; D010087:Oxides; C097921:ferumoxtran-10; D007501:Iron; D017364:Collagenases; D018093:Gelatinases; D008666:Metalloendopeptidases; C120487:pro-matrix metalloproteinase 9; C069860:progelatinase; D020780:Matrix Metalloproteinase 9; D052203:Ferrosoferric Oxide