Spin locking for magnetic resonance imaging with application to human breast

The dependence of rotating frame spin‐lattice relaxation, T 1ρ , on locking field frequency, f 1 was measured for phantom materials and human breast tissues. These data were used to predict the relative signal strengths obtainable in a spin‐locking imaging sequence. This imaging sequence was implemented on a 0.15‐T imaging system and measurements of phantom and tissue signal strength for various imaging parameters agreed with predicted signal strengths. Compared to T 1 and T 2 , T 1ρ appears to have unique capability to distinguish tumor from normal fat and fibrous breast tissues. The applications of T 1ρ , to tissue characterization and imaging at high static field strengths are discussed. © 1989 Academic Press, Inc.