title: In vivo study of microbubbles as an MR susceptibility contrast agent.
abstract: The potential application of gas microbubbles as a unique intravascular susceptibility contrast agent for MRI has not been fully explored. In this study, the MR susceptibility effect of an ultrasound microbubble contrast agent, Optison, was studied with rat liver imaging at 7 T. Optison suspension in two different doses (0.15 mL/kg and 0.4 mL/kg) was injected into rats, and induced transverse relaxation rate increases (deltaR2*) of 29.1 +/- 1.6 s(-1) (N = 2) and 61.5 +/- 12.9 s(-1) (N = 6), respectively, in liver tissue. Liver uptake of intact albumin microbubbles was observed 10 min after injection. Eight of the 16 rats studied showed no susceptibility enhancement. This is probably attributable to the intravascular microbubble growth due to transmural CO2 supersaturation in the cecum and colon in small animals that causes microbubble aggregation and trapping in the inferior vena cava (IVC). In vitro deltaR2* measurements of Optison suspension at different concentrations are also reported.
authors.affiliation: Jockey Club MRI Engineering Center, University of Hong Kong.
authors.forename: Kelvin K
authors.initials: KK
authors.lastname: Wong
authors.forename: Ingjye
authors.initials: I
authors.lastname: Huang
authors.forename: Young R
authors.initials: YR
authors.lastname: Kim
authors.forename: Haiying
authors.initials: H
authors.lastname: Tang
authors.forename: Edward S
authors.initials: ES
authors.lastname: Yang
authors.forename: Kenneth K
authors.initials: KK
authors.lastname: Kwong
authors.forename: Ed X
authors.initials: EX
authors.lastname: Wu
mesh_terms: D000418:Albumins / Q000008:administration & dosage / Q000493:pharmacokinetics*; D000818:Animals; D003287:Contrast Media / Q000008:administration & dosage / Q000493:pharmacokinetics*; D052203:Ferrosoferric Oxide; D005466:Fluorocarbons / Q000008:administration & dosage / Q000493:pharmacokinetics*; D007501:Iron / Q000008:administration & dosage; D008099:Liver / Q000378:metabolism*; D008279:Magnetic Resonance Imaging; D008863:Microspheres; D010087:Oxides / Q000008:administration & dosage; D019047:Phantoms, Imaging; D051381:Rats
chemical_list: D000418:Albumins; D003287:Contrast Media; C099458:FS 069; D005466:Fluorocarbons; D010087:Oxides; D007501:Iron; D052203:Ferrosoferric Oxide