In vivo multiple spin echoes

The demagnetizing field produced by the nuclear polarization can induce refocusing of multiple spin echoes. We show that multiple spin echoes can be observed in vivo with a clinical MR system at 1.5 T. Strategies for the spatial localization of the multiple spin echo signals are considered. Multiple spin echo studies in brain white matter and skeletal muscle in healthy volunteers are reported. The dependence of the signal amplitudes on the experimental parameters is compared with the theory. The sources of contrast for MRI and the perspectives for medical applications are discussed. (C) 1998 Academic Press.