Blood-pool MR contrast material for detection and characterization of focal hepatic lesions: initial clinical experience with ultrasmall superparamagnetic iron oxide (AMI-227).
OBJECTIVE
AMI-227 is an ultrasmall superparamagnetic iron oxide colloid known to enhance tissue T1 and T2 relaxation rates. Animal studies show that AMI-227 has an estimated blood half-life of more than 200 min. In this study, we evaluated the clinical utility of AMI-227 as an MR contrast agent for detection and characterization of focal hepatic lesions, with MR imaging done while the contrast agent is in the intravascular space (blood-pool phase).


METHODS
Twenty-two patients with known or suspected focal hepatic masses underwent T1- and T2-weighted MR imaging of the liver at 1.5 T before and immediately after drip infusion of AMI-227 at doses of 0.8, 1.1, or 1.7 mg Fe/kg. Unenhanced and contrast-enhanced images were analyzed qualitatively (lesion detection and tissue characterization) and quantitatively (lesion-liver contrast-to-noise ratio).


RESULTS
AMI-227 enhanced signal in normal liver and blood vessels on T1-weighted images and decreased signal in these tissues on T2-weighted images. Qualitatively and quantitatively, lesion-liver contrast was increased for solid tumors (non-cyst and nonhemangioma) at all three doses (p < .02) on both T1- and T2-weighted images. Differentiation between blood vessels and small lesions was easier on contrast-enhanced images, which allowed increased confidence in excluding lesions. Unique enhancement patterns were noted for hemangiomas, solid tumors, and cysts.


CONCLUSIONS
Initial clinical experience suggests that AMI-227 is a useful contrast agent for detection and characterization of focal hepatic lesions.
Saini
S
S
Department of Radiology, Harvard Medical School, Boston, MA 02114, USA.
Edelman
R R
RR
Sharma
P
P
Li
W
W
Mayo-Smith
W
W
Slater
G J
GJ
Eisenberg
P J
PJ
Hahn
P F
PF
D000328:Adult; D000368:Aged; D006528:Carcinoma, Hepatocellular / Q000175:diagnosis; D018281:Cholangiocarcinoma / Q000175:diagnosis; D003110:Colonic Neoplasms / Q000175:diagnosis; D003287:Contrast Media; D003560:Cysts / Q000175:diagnosis; D003911:Dextrans; D005260:Female; D052203:Ferrosoferric Oxide; D006391:Hemangioma / Q000175:diagnosis; D018197:Hepatoblastoma / Q000175:diagnosis; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007501:Iron; D008099:Liver / Q000098:blood supply / Q000473:pathology*; D008107:Liver Diseases / Q000175:diagnosis*; D008113:Liver Neoplasms / Q000175:diagnosis / Q000556:secondary; D008279:Magnetic Resonance Imaging; 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