Clinical use of the partial saturation and saturation recovery sequences in MR imaging

The partial saturation (PS) (90 degree-data collection) and saturation recovery (SR) [(90 degree-dephase)n-90 degree-data collection] sequences are described. The early data collection of the PS sequence is of value in demonstrating tissues with a short T2 such as articular cartilage and the annulus fibrosus. The PS sequence also highlights flow and this may provide specific information in vascular lesions. Appropriate choice of echo time enables chemical shift effects to be seen in normal tissues such as breast and bone marrow as well as a variety of diseases such as bone marrow infiltration, pancreatitis, and fatty infiltration of the liver in which there is mixed lipid and water. The SR sequence can be used to control flow effects as well as to calculate values of T1. Although PS and SR sequences display less T1 and T2 dependent contrast than conventional highly T1 and T2 dependent inversion recovery and spin echo sequences, they may still be of clinical value when the mechanism of contrast formation is change in proton density, chemical shift effects, flow effects, or detection of short T2 tissue components.