title: Intravenous manganese-mesoporphyrin as a magnetic resonance imaging contrast agent: an experimental model using VX-2 carcinoma in rabbits.
abstract: OBJECTIVE
  We investigated the potential of manganese (III) mesoporphyrin (Mn-mesoporphyrin) as a hepatobiliary contrast agent for magnetic resonance (MR) imaging in rabbits given VX-2 carcinoma liver implants.
  
  
  METHODS
  Rabbits given VX-2 carcinoma liver implants (n = 8) were imaged before and after the intravenous (i.v.) administration of 0.04 mmol/kg Mn-mesoporphyrin. MR images were correlated with gross-specimen cross-sections. The distribution of Mn in various tissues following i.v. administration of 0.04 mmol/kg Mn-mesoporphyrin was determined using atomic absorption analysis. A standard panel of serum chemistries was followed over 7 days in six rabbits following this same dose of Mn-mesoporphyrin and compared with chemistries from two control rabbits.
  
  
  RESULTS
  I.v. administration of 0.04 mmol/kg (25 mg/kg) Mn-mesoporphyrin resulted in improvement of tumor-to-liver contrast, with enhancement of normal liver (99.7 +/- 14.7%) and the gallbladder (442 +/- 116%), but not VX-2 tumor tissue (14.8 +/- 13.9%), (n = 8, p = .05). Analysis of tissue Mn levels 100 min after i.v. Mn-mesoporphyrin injection demonstrated preferential distribution of Mn to normal liver tissue (57.8 +/- 15.3 micrograms Mn/g) compared with VX-2 tumor (4.28 +/- 1.48 micrograms Mn/g). No significant change was found in the serum chemistries of six normal rabbits over a 7-day period after the i.v. administration of 0.04 mmol/kg Mn-mesoporphyrin.
  
  
  CONCLUSIONS
  I.v. Mn-mesoporphyrin improved lesion-to-liver contrast because of preferential distribution of Mn-mesoporphyrin to normal liver parenchyma and bile.
authors.affiliation: Department of Radiology, University of Washington School of Medicine, Seattle 98195, USA.
authors.forename: D H
authors.initials: DH
authors.lastname: Robinson
authors.forename: U P
authors.initials: UP
authors.lastname: Schmiedl
authors.forename: F L
authors.initials: FL
authors.lastname: Starr
authors.forename: J A
authors.initials: JA
authors.lastname: Nelson
authors.forename: R
authors.initials: R
authors.lastname: Malek
mesh_terms: D000818:Animals; D002277:Carcinoma / Q000175:diagnosis* / Q000473:pathology; D016001:Confidence Intervals; D003287:Contrast Media / Q000008:administration & dosage*; D004195:Disease Models, Animal; D005704:Gallbladder / Q000473:pathology*; D007262:Infusions, Intravenous; D008099:Liver / Q000473:pathology*; D008114:Liver Neoplasms, Experimental / Q000175:diagnosis* / Q000473:pathology; D008279:Magnetic Resonance Imaging; D008345:Manganese / Q000008:administration & dosage; D008652:Mesoporphyrins / Q000008:administration & dosage; D008665:Metalloporphyrins / Q000008:administration & dosage; D009368:Neoplasm Transplantation; D011817:Rabbits; D014018:Tissue Distribution
chemical_list: D003287:Contrast Media; D008652:Mesoporphyrins; D008665:Metalloporphyrins; D008345:Manganese