A long-duration, low-power, off-resonance spin-locking pulse was incorporated into the COSY revamped by asymmetric z gradient-echo detection (CRAZED) pulse sequence in order to evaluate the effects of intermolecular double-quantum longitudinal relaxation in the tilted rotating frame (T1rho,DQ(eff)). This modified CRAZED sequence was followed by a standard fast spin-echo imaging sequence to form images with T1rho,DQ(eff)-weighted contrast. Imaging experiments were performed on an agarose-gel phantom and mouse-tail tissue at 600 MHz. Experimental results demonstrated the feasibility of imaging applications based on T1rho,DQ(eff) as a novel contrast mechanism, and showed that iDQC off-resonance longitudinal relaxation in the rotating frame T1rho,DQ(eff) is sensitive to the tilt angle theta and the effective spin-locking field omegae. Imaging based on T1rho,DQ(eff)) has reduced RF power deposition compared to on-resonance spin-locking, which is advantageous for human applications.
Copyright 2006 Wiley-Liss, Inc.