Ultrashort TE T1ρ magic angle imaging

Abstract

An ultrashort TE T1ρ sequence was used to measure T 1ρ of the goat posterior cruciate ligament (n = 1) and human Achilles tendon specimens (n = 6) at a series of angles relative to the B 0 field and spin-lock field strengths to investigate the contribution of dipole-dipole interaction to T1ρ relaxation. Preliminary results showed a significant magic angle effect. T1ρ of the posterior cruciate ligament increased from 6.9 ± 1.3 ms at 0° to 36 ± 5 ms at 55° and then gradually reduced to 12 ± 3 ms at 90°. Mean T1ρ of the Achilles tendon increased from 5.5 ± 2.2 ms at 0° to 40 ± 5 ms at 55°. T1ρ dispersion study showed a significant T1ρ increase from 2.3 ± 0.9 ms to 11 ± 3 ms at 0° as the spin-lock field strength increased from 150 Hz to 1 kHz, and from 30 ± 3 ms to 42 ± 4 ms at 55° as the spin-lock field strength increased from 100 to 500 Hz. These results suggest that dipolar interaction is the dominant T1ρ relaxation mechanism in tendons and ligaments. Copyright © 2012 Wiley Periodicals, Inc.