title: In vivo quantification of the unidirectional influx constant for Gd-DTPA diffusion across the myocardial capillaries with MR imaging.
abstract: The authors present an in vivo method for measuring the unidirectional influx constant (Ki) for gadolinium diethylenetriaminepentaacetic acid (DTPA) diffusion across the capillary membrane in the human myocardium with magnetic resonance imaging. Ki is related to the extraction fraction (E) and the perfusion (F) by the equation Ki = E.F.Ki was obtained by using the longitudinal relaxation rate (R1) as a measure of the myocardial concentration of Gd-DTPA in the mathematical model for transcapillary transport across capillary membranes. Myocardial enhancement after Gd-DTPA injection was followed by using inversion-recovery Turbo-FLASH (fast low-angle shot) images obtained in real time. The results were comparable to those obtained from studies with positron emission tomography in humans and invasive studies in animals. A method for obtaining the input function noninvasively is also presented. Comparison with direct arterial blood sampling showed that the noninvasive input function may be even more accurate with regard to timing and curve shape than the invasive input function. The procedure may therefore prove useful in clinical studies.
authors.affiliation: Danish Research Center of Magnetic Resonance, Hvidovre Hospital, University of Copenhagen.
authors.forename: H B
authors.initials: HB
authors.lastname: Larsson
authors.forename: M
authors.initials: M
authors.lastname: Stubgaard
authors.forename: L
authors.initials: L
authors.lastname: Søndergaard
authors.forename: O
authors.initials: O
authors.lastname: Henriksen
mesh_terms: D000328:Adult; D002199:Capillary Permeability; D003287:Contrast Media / Q000493:pharmacokinetics; D003326:Coronary Circulation / Q000502:physiology*; D005682:Gadolinium; D019786:Gadolinium DTPA; D006321:Heart / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008955:Models, Cardiovascular; D008961:Models, Structural; D009942:Organometallic Compounds / Q000493:pharmacokinetics; D004369:Pentetic Acid / Q000031:analogs & derivatives* / Q000493:pharmacokinetics; D014055:Tomography, Emission-Computed
chemical_list: D003287:Contrast Media; D009942:Organometallic Compounds; D004369:Pentetic Acid; D005682:Gadolinium; D019786:Gadolinium DTPA