title: Dual-contrast MR imaging of liver cancer in rats.
abstract: MR contrast agents increase hepatic tumor conspicuity, as measured in terms of contrast-to-noise (C/N) ratios. With an animal model of hepatic metastases from breast cancer, IV administration of Gd-DTPA (0.2 mmol/kg) shows a biphasic time response, transiently increasing the signal intensity of liver relative to tumor, with C/N ratio magnitudes increasing from -5.7 to -16.3 (SE 250/20); after a delay, the signal intensity of tumor increases relative to liver with a reversal of the C/N sign from negative to positive and an increase in the C/N magnitude to +25.0. IV administration of ferrite particles (0.05 mmol Fe/kg) shows a monophasic time response, increasing signal intensity of tumor relative to liver from +1.5 to +49.5 (SE 500/30). When both contrast agents were administered together (dual-contrast technique), the tumor-liver C/N magnitude reached a maximum of +67.8 (SE 500/30) 12 min after drug infusion. Analysis of individual contrast and noise factors contributing to this technique revealed a strong correlation between the signal intensity of liver and the signal intensity of ghost artifacts, which increase after administration of Gd-DTPA (r = .89) and decrease after administration of ferrite (r = 1.0). Dual-contrast imaging shows a synergistic addition of contrast and suppression of noise from ghost artifacts, maximizing the C/N and increasing the conspicuity of focal liver lesions.
authors.affiliation: Department of Radiology, Massachusetts General Hospital, Harvard Medical School, 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: J
authors.initials: J
authors.lastname: Wittenberg
authors.forename: J T
authors.initials: JT
authors.lastname: Ferrucci
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D005260:Female; D005290:Ferric Compounds / Q000008:administration & dosage; D005682:Gadolinium / Q000008:administration & dosage; D019786:Gadolinium DTPA; D008113:Liver Neoplasms / Q000556:secondary; D008114:Liver Neoplasms, Experimental / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008325:Mammary Neoplasms, Experimental; D009368:Neoplasm Transplantation; D009942:Organometallic Compounds / Q000008:administration & dosage; D004369:Pentetic Acid / Q000008:administration & dosage; D051381:Rats; D011916:Rats, Inbred F344
chemical_list: D005290:Ferric Compounds; D009942:Organometallic Compounds; C001215:ferrite; D004369:Pentetic Acid; D005682:Gadolinium; D019786:Gadolinium DTPA