Pulsed magnetization transfer contrast MRI by a sequence with water selective excitation

A water selective SE imaging sequence was developed providing suitable properties for the assessment of magnetization transfer (MT) effects in tissues with considerable amounts of fat.

The sequence with water selective excitation and slice selective refocusing combines the following features: The RF exposure on the macromolecular protons is relatively low for single slice imaging without MT prepulses, since no additional pulses for fat saturation are necessary. Water selection by frequency selective excitation diminishes faults in the subtraction of images recorded with and without MT prepulses (which might arise from movements).

High differences in the signal amplitudes from hyaline cartilage and muscle tissue were obtained comparing images recorded with irradiation of the series of prepulses for MT and those lacking MT prepulses. Utilizations of the described water selective approach for the assessment of MT effects in lesions of cartilage and bone are demonstrated. MT saturation was also examined in muscles with fatty degeneration of patients suffering from progressive muscular dystrophy.

The described technique allows determination of MT effects with good precision in a single slice, especially in regions with dominating fat signals.