High frequency modulated gradient spin echo diffusion measurements with chemical shift resolution

Abstract

We present a Modulated Gradient Spin Echo pulse sequence that enables diffusion measurements with chemical shift resolution in the obtained spectra at higher modulation frequencies (1600 Hz) than previously obtained. The modulation is generated using a Carr-Purcell-Meiboom-Gill train of radiofrequency pulses in a constant gradient. To avoid distortions from eddy currents, a longitudinal eddy current delay was added between gradient modulation and spectrum acquisition. To suppress the effects from gradient-slicing and unwanted coherences, while maintaining high chemical shift resolution, short samples (height of 0.5 mm) were prepared in a 5 mm Shigemi™ tube. The pulse sequence was successfully tested on a sample of distilled water and a sample of a water-continuous microemulsion (Winsor’s type I).