MUSCULOSKELETAL MR-IMAGING AT 4 T AND AT 1.5 T - COMPARISON OF RELAXATION-TIMES AND IMAGE-CONTRAST

PURPOSE: To evaluate the relaxation time-based contrast between the ma in tissues of the musculoskeletal system as measured in the human knee with magnetic resonance imaging at 4 T and 1.5 T. MATERIALS AND METHO DS: Five volunteers underwent 4-T and 1.5-T imaging. Inversion-recover y series were used to measure T1 values, and T2 values were; measured with a spin-echo sequence. RESULTS: T1 values increased in all tissues with 4-T imaging. Values increased in muscle from 1 to 1.8 seconds, i n fat from 0.3 to 0.4 Seconds, and in cartilage from 0.8 to 1.5 second s. T2 values were 10%-20% Shorter in all tissues at 4 T. CONCLUSION: A dvantages of 4-T imaging compared with 1.5-T imaging include a higher signal-to noise ratio and an improved signal difference-to-noise ratio . However, any improvement in signal-to-noise ratio at high field stre ngths can partially be reduced by the increase in the T1 value. The sl ightly shorter T2 values at 4 T do not affect image contrast.