title: Three-dimensional fluid pressure mapping in porous media using magnetic resonance imaging with gas-filled liposomes.
abstract: This paper presents and demonstrates a method for using magnetic resonance imaging to measure local pressure of a fluid saturating a porous medium. The method is tested both in a static system of packed silica gel and in saturated sintered glass cylinders experiencing fluid flow. The fluid used contains 3% gas in the form of 3-mum average diameter gas filled 1,2-distearoyl-sn-glycero-3-phosphocholine (C18:0, MW: 790.16) liposomes suspended in 5% glycerol and 0.5% Methyl cellulose with water. Preliminary studies at 2.35 T demonstrate relative magnetic resonance signal changes of 20% per bar in bulk fluid for an echo time T(E)=40 ms, and 6-10% in consolidated porous media for T(E)=10 ms, over the range 0.8-1.8 bar for a spatial resolution of 0.1 mm(3) and a temporal resolution of 30 s. The stability of this solution with relation to applied pressure and methods for improving sensitivity are discussed.
authors.affiliation: School of Biomedical and Natural Sciences, Nottingham Trent University, Nottingham, NG11 8NS, UK. rob.morris@ntu.ac.uk
authors.forename: Robert H
authors.initials: RH
authors.lastname: Morris
authors.forename: Martin
authors.initials: M
authors.lastname: Bencsik
authors.forename: Anil K
authors.initials: AK
authors.lastname: Vangala
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Perrie
mesh_terms: D003287:Contrast Media; D005740:Gases / Q000032:analysis*; D005898:Glass; D005990:Glycerol; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008081:Liposomes; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008747:Methylcellulose; D045423:Microbubbles; D010539:Permeability; D010713:Phosphatidylcholines; D016062:Porosity; D011312:Pressure; D012680:Sensitivity and Specificity; D058428:Silica Gel; D012822:Silicon Dioxide; D013997:Time Factors; D014867:Water
chemical_list: D003287:Contrast Media; D005740:Gases; D008081:Liposomes; D010713:Phosphatidylcholines; D014867:Water; D058428:Silica Gel; D012822:Silicon Dioxide; D008747:Methylcellulose; C010942:1,2-distearoyllecithin; D005990:Glycerol