Encoding of diffusion and T1 in the CPMG echo shape: single-shot D and T1 measurements in grossly inhomogeneous fields.
We present a new approach of NMR measurements in the presence of grossly inhomogeneous fields where information is encoded in the echo shape of CPMG trains. The method is based on sequences that consist of an initial encoding sequence that generates echoes with contributions from at least two different coherence pathways that are then both refocused many times by a long string of closely spaced identical pulses. The generated echoes quickly assume an asymptotic shape that encodes the information of interest. High signal-to-noise ratios can be achieved by averaging the large number of echoes. We demonstrate this approach with different implementations of the measurements of longitudinal relaxation time, T(1), and diffusion coefficient, D. It is shown that the method can be used for novel single-shot measurements.
Hürlimann
Martin D
MD
Schlumberger-Doll Research, Old Quarry Road, Ridgefield, CT 06877, USA. hurlimann@slb.com
D000465:Algorithms; D016880:Anisotropy; D003198:Computer Simulation; D004058:Diffusion; D016247:Information Storage and Retrieval / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008956:Models, Chemical; D008958:Models, Molecular