title: Quantitation of intermolecular dipolar effects in NMR spectroscopy and high order MSE MR imaging.
abstract: An analytical expression for intermolecular dipolar effects was derived for the CRAZED sequence with an arbitrary flip angle of the second RF pulse and time-varying gradients. A combination of the demagnetizing field theory and product operator formalism was utilized in the derivation. It is demonstrated that the time-averaged, not instantaneous, orientation of the applied gradients determines the contributions of long-range intermolecular dipole effects. An imaging sequence to detect intermolecular dipolar effects was designed. The second- and third-order multiple spin echo (MSE) NMR signals of swine muscle were observed and were found to be in good agreement with the theoretical predictions. MSE images of a water phantom with nth orders (n = 2, - 3, - 4, and - 5) were also obtained, and their relative signal intensities and optimized TE values were elucidated and compared with the theoretical prediction.
authors.affiliation: Department of Radiology, University of Rochester Medical Center, University of Rochester, NY 14642-8648, USA.
authors.forename: Z
authors.initials: Z
authors.lastname: Chen
authors.forename: S D
authors.initials: SD
authors.lastname: Kennedy
authors.forename: J
authors.initials: J
authors.lastname: Zhong
mesh_terms: D000818:Animals; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods* / Q000706:statistics & numerical data; D009682:Magnetic Resonance Spectroscopy / Q000379:methods* / Q000706:statistics & numerical data; D008962:Models, Theoretical; D009132:Muscles / Q000033:anatomy & histology / Q000378:metabolism; D019047:Phantoms, Imaging; D013552:Swine