title: Pyogenic liver abscess: contrast-enhanced MR imaging in rats.
abstract: MR imaging was used to evaluate experimentally induced pyogenic liver abscesses in an animal model. Rats were examined before and after IV administration of either gadolinium-diethylenetriaminepentaacetic acid (Gd-DTPA), ferrite particles, or both contrast agents together. Pyogenic liver abscesses appeared hypointense on T1-weighted images and hyperintense on T2-weighted images. Bolus administration of Gd-DTPA using a fast spin-echo sequence with repetition time of 250 msec and echo time of 20 msec (SE 250/20) showed transient selective enhancement of normal hepatic tissue and increased lesion conspicuity, quantitatively assessed by the contrast-to-noise ratio, which increased from -35.7 to -59.0. Delayed leakage of Gd-DTPA into the abscess center partially obscured small lesions at 30-60 min. Ferrite particles reduced the signal intensity of normal liver, and the abscess then appeared homogenously hyperintense. Applying the SE 500/32 sequence, the contrast-to-noise ratio increased from -1.2 to +74.0. Coordinated administration of both contrast agents showed a further increase in contrast to +94.0, with a hyperintense abscess rim surrounded by hypointense liver. Gd-DTPA increases abscess-liver contrast by rim enhancement of the abscess wall, and ferrite increases the abscess-liver contrast by selectively decreasing the signal intensity of surrounding normal liver. As a result of increased contrast-to-noise ratio, both contrast agents, alone or in combination, increase the conspicuity of hepatic abscesses.
authors.affiliation: Department of Radiology, Massachusetts General Hospital, Boston 02114.
authors.forename: R
authors.initials: R
authors.lastname: Weissleder
authors.forename: S
authors.initials: S
authors.lastname: Saini
authors.forename: D D
authors.initials: DD
authors.lastname: Stark
authors.forename: G
authors.initials: G
authors.lastname: Elizondo
authors.forename: C
authors.initials: C
authors.lastname: Compton
authors.forename: J
authors.initials: J
authors.lastname: Wittenberg
authors.forename: J T
authors.initials: JT
authors.lastname: Ferrucci
mesh_terms: D000818:Animals; D001424:Bacterial Infections / Q000175:diagnosis*; D003287:Contrast Media / Q000008:administration & dosage*; D005290:Ferric Compounds; D005682:Gadolinium; D019786:Gadolinium DTPA; D008100:Liver Abscess / Q000175:diagnosis*; D008279:Magnetic Resonance Imaging; D009942:Organometallic Compounds; D004369:Pentetic Acid; D051381:Rats; D011919:Rats, Inbred Strains; D013492:Suppuration
chemical_list: D003287:Contrast Media; D005290:Ferric Compounds; D009942:Organometallic Compounds; C001215:ferrite; D004369:Pentetic Acid; D005682:Gadolinium; D019786:Gadolinium DTPA