MULTISLICE T1-WEIGHTED HYBRID RARE IN CNS IMAGING - ASSESSMENT OF MAGNETIZATION-TRANSFER EFFECTS AND ARTIFACTS

using a T1-weighted hybrid rapid acquisition with relaxation enhanceme nt (RARE) MR sequence that implements an echo-to-view mapping scheme t ermed ''low-high profile order,'' we evaluated signal intensity change s in different brain tissues as a function of number of slices, inters lice gap, and echo train length (ETL). We also measured phase-encode a nd frequency-encode noise as well as blurring artifacts along the phas e-encode direction as a function of ETL. Off-resonance magnetization t ransfer effects were demonstrated to be responsible for signal intensi ties changes in white matter and gray matter when using multislice tec hniques, These effects are amplified by increasing the number of slice s and ETL. Due to the nature of the implemented echo-to-view mapping s cheme, no on-resonance magnetization transfer effects were observed fr om the intraslice echo train, Selective background (white matter and g ray matter) suppression in multislice T1-weighted hybrid RARE, seconda ry to off-resonance magnetization transfer effects, may provide better contrast resolution of enhancing central nervous system (CNS) lesions at much shorter scan time as compared to conventional spin-echo T1-we ighted sequences. This improvement in contrast resolution as a functio n of ETL maybe limited by worsening phase-encode noise and blurring ar tifacts.