title: Quantification of the effect of water exchange in dynamic contrast MRI perfusion measurements in the brain and heart.
abstract: Measurement of myocardial and brain perfusion when using exogenous contrast agents (CAs) such as gadolinium-DTPA (Gd-DTPA) and MRI is affected by the diffusion of water between compartments. This water exchange may have an impact on signal enhancement, or, equivalently, on the longitudinal relaxation rate, and could therefore cause a systematic error in the calculation of perfusion (F) or the perfusion-related parameter, the unidirectional influx constant over the capillary membranes (K(i)). The aim of this study was to quantify the effect of water exchange on estimated perfusion (F or K(i)) by using a realistic simulation. These results were verified by in vivo studies of the heart and brain in humans. The conclusion is that water exchange between the vascular and extravascular extracellular space has no effect on K(i) estimation in the myocardium when a normal dose of Gd-DTPA is used. Water exchange can have a significant effect on perfusion estimation (F) in the brain when using Gd-DTPA, where it acts as an intravascular contrast agent.
authors.affiliation: Danish Research Center for Magnetic Resonance, Hvidovre Hospital, University of Copenhagen, Copenhagen, Denmark. henrikl@magnet.drcmr.dk
authors.forename: H B
authors.initials: HB
authors.lastname: Larsson
authors.forename: S
authors.initials: S
authors.lastname: Rosenbaum
authors.forename: T
authors.initials: T
authors.lastname: Fritz-Hansen
mesh_terms: D001834:Body Water / Q000378:metabolism*; D001921:Brain / Q000098:blood supply* / Q000378:metabolism*; D003198:Computer Simulation; D003287:Contrast Media / Q000008:administration & dosage / Q000493:pharmacokinetics; D003326:Coronary Circulation / Q000502:physiology*; D004058:Diffusion; D019786:Gadolinium DTPA / Q000008:administration & dosage / Q000493:pharmacokinetics; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008433:Mathematics; D009206:Myocardium / Q000378:metabolism*; D018709:Statistics, Nonparametric
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA