ABDOMINAL MR-ANGIOGRAPHY PERFORMED USING BLOOD-POOL CONTRAST AGENTS -COMPARISON OF A NEW SUPERPARAMAGNETIC IRON-OXIDE NANOPARTICLE AND A LINEAR GADOLINIUM POLYMER

OBJECTIVE.We evaluated and compared two different experimental blood p ool contrast agents for abdominal MR angiography in an animal model. M ATERIALS AND METHODS.In seven pigs, coronal T1-weighted three-dimensio nal fast field-echo images were obtained on a conventional 1.5-T MR im aging system before and after IV injection of the ultrasmall superpara magnetic iron oxide agent FeO-BPA. In another seven pigs, MR angiogram s were acquired using the gadolinium polymer WIN 22181. Enhanced image s were obtained 5-210 min after injection of FeO-BPA and 1-120 min aft er injection of WIN 22181. RESULTS. Both blood pool agents yielded det ailed angiograms of the abdominal vascular tree when imaging lasted 2 min. In-plane running vessels were imaged without saturation effects a nd with equivalent maximum signal-to-noise ratios. Half the maximum si gnal-to-noise ratio was reached 150 min after injection of FeO-BPA, wh ereas this interval was approximately 70 min for the gadolinium polyme r. Because of these different imaging half-life periods, the effective diagnostic window provided by FeO-BPA was six to eight times longer t han that of WIN 22181. In the liver, the vascular T1 shortening and th e parenchymal T2 effect of FeO-BPA complemented each other, resulting in an optimal contrast-to-noise ratio significantly higher than that achieved with WIN 22181. This ''double-contrast effect'' in the liver was especially helpful when obtaining detailed MR portograms. CONCLUSI ON. The blood pool agents FeO-BPA and WIN 22181 can be used to produce high-quality abdominal MR angiograms on standard MR imaging equipment . The contrast-to-noise ratio of hepatic vessels is best on iron oxide -enhanced images because of a T1-T2 synergistic effect in the liver. The longer diagnostic window provided by FeO-BPA coupled with the opti on of in-plane imaging suggests the usefulness of FeO-BPA in future MR imaging-guided Vascular interventions.