Quantitation of intermolecular dipolar effects in NMR spectroscopy and high order MSE MR imaging

✍ Scribed by Chen, Z

• Publisher: Springer
• Year: 2000
• Tongue: English
• Weight: 160 KB
• Volume: 11
• Category: Article
• ISSN: 0968-5243
• DOI: 10.1016/s1352-8661(00)00127-7

✦ Synopsis

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.