Magnetic resonance imaging of short T2 species with improved contrast

摘要

Magnetic resonance signals for imaging species having short spin-spin relaxation times (T₂) are obtained without the need for a refocusing lobe. A series of RF excitation pulses are applied to the species with magnetic resonance signals being detected after each RF excitation pulse is applied. The magnetic resonance signals are then combined to provide the imaging signals. In one embodiment, each RF excitation pulse is half of a conventional slice-selective pulse with each pulse being slewed to zero. Contrast between the imaged short T₂ species and longer T₂ species can be enhanced by first applying an RF signal having sufficient amplitude to excite the longer T₂ species but insufficient amplitude to excite the short T₂ species whereby the longer T₂ species are tipped by the RF signal. A magnetic gradient can then be applied to dephase the tipped nuclei of the longer T₂ species. The imaging signals are then obtained from magnetic resonance signals from the short T₂ species.