title: Interactions of paramagnetic contrast agents and the spin echo pulse sequence.
abstract: The theoretical equations for paramagnetic contrast agent effects and the spin echo pulse sequence are combined to graph magnetic resonance (MR) intensity as a function of paramagnetic contrast agent concentration for various tissues. Analysis of the graphs and equations demonstrate several technical and clinical implications. These include: (1) positive enhancement is most likely to occur with short TEs and TRs; (2) changes in machine parameters TE and TR will change the concentration of agent at which the peak enhancing MR intensity will occur; (3) there is an absolute maximum MR intensity that can be reached with contrast enhancement; (4) the maximum MR intensity reached with enhancement is dependent on the tissues' T2 and, to a lesser degree, T1 relaxation times; (5) certain TE and TR combinations will cause no enhancement; (6) if positive enhancement does occur, it will usually occur only over a limited range of agent concentration; and (7) the tissues' T1 relaxation time but not its T2 time determines whether positive enhancement will occur and the relative amount of enhancement.
authors.affiliation: Pittsburgh NMR Institute, Department of Radiology, University of Pittsburgh, Pennsylvania 15213.
authors.forename: P L
authors.initials: PL
authors.lastname: Davis
authors.forename: D L
authors.initials: DL
authors.lastname: Parker
authors.forename: J A
authors.initials: JA
authors.lastname: Nelson
authors.forename: J S
authors.initials: JS
authors.lastname: Gillen
authors.forename: V M
authors.initials: VM
authors.lastname: Runge
mesh_terms: D003287:Contrast Media; D019786:Gadolinium DTPA; D006801:Humans; D008279:Magnetic Resonance Imaging; D009942:Organometallic Compounds; D004369:Pentetic Acid
chemical_list: D003287:Contrast Media; D009942:Organometallic Compounds; D004369:Pentetic Acid; D019786:Gadolinium DTPA