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 iran 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), SUBJECTS AND 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 TP-weighted images. Qualitatively and quantitatively, lesion-liver contrast was increased for solid tumors (noncyst and nonhemangioma) at all three doses (p < .02) on both T1- and TS-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, CONCLUSION, Initial clinical experience suggests that AMI-227 is a useful contrast agent for detection and characterization of focal hepatic lesions.