title: Phase modulation in dipolar-coupled A2 spin systems: effect of maximum state mixing in 1H NMR in vivo.
abstract: Coupling constants of nuclear spin systems can be determined from phase modulation of multiplet resonances. Strongly coupled systems such as citrate in prostatic tissue exhibit a more complex modulation than AX connectivities, because of substantial mixing of quantum states. An extreme limit is the coupling of n isochronous spins (An system). It is observable only for directly connected spins like the methylene protons of creatine and phosphocreatine which experience residual dipolar coupling in intact muscle tissue in vivo. We will demonstrate that phase modulation of this "pseudo-strong" system is quite simple compared to those of AB systems. Theory predicts that the spin-echo experiment yields conditions as in the case of weak interactions, in particular, the phase modulation depends linearly on the line splitting and the echo time.
authors.affiliation: Abteilung Medizinische Physik in der Radiologie, Deutsches Krebsforschungszentrum (dkfz), D-69120 Heidelberg, Germany. l.schroeder@dkfz-heidelberg.de
authors.forename: Leif
authors.initials: L
authors.lastname: Schröder
authors.forename: Christian
authors.initials: C
authors.lastname: Schmitz
authors.forename: Peter
authors.initials: P
authors.lastname: Bachert
mesh_terms: D003401:Creatine / Q000737:chemistry*; D006801:Humans; D006838:Hydrocarbons / Q000737:chemistry; D006860:Hydrogen Bonding; D007866:Leg; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D008697:Methane / Q000031:analogs & derivatives* / Q000737:chemistry; D018482:Muscle, Skeletal / Q000737:chemistry*
chemical_list: D006838:Hydrocarbons; C030011:carbene; D003401:Creatine; D008697:Methane