Spin-lock imaging in contrast-enhanced magnetic resonance imaging of human gliomas.

Abstract

t R ecent reports have described an improvement in contrast-to-noise ratios wtlen the use of paramagnetic contrast material is combined with magnetization transfer imaging [1-3]. It has been suggested that similar relaxation processes affect spin-lock and magnetization transfer imaging [4]. The spin-lock techniques enable the study of relaxation processes that are effective at low field strengths with a high signal-to-noise ratio. In a spin-lock experiment, nuclear spins are locked with a radiofrequency field. The locked nuclear magnetization relaxes along the locking field. Because tile observed relaxation time probes the low-frequency range, it is likely to be more sensitive to changes in concentration, mobility, and interactions of macromolecules than T1 obtained at higher field strengths. A muhislice spin-lock imaging technique has recently been introduced [5]. In this study, we investigated whether the use of paramagnetic contrast material with spin-lock imaging could improve the contrast-to-noise ratio or contrast ratio of enhancing brain tumors.