Single‐shot spiral image acquisition with embedded z‐shimming for susceptibility signal recovery

Abstract

Purpose To efficiently and effectively recover the susceptibility‐induced signal losses for functional MRI (fMRI) experiments. Materials and Methods The signal losses near air/tissue interfaces at the ventral brain regions introduce difficulties in the neuroimaging studies concerned with brain functions such as memory, emotion, and olfaction processes. The z‐shimming technique has been introduced in fMRI image acquisition to recover such losses. One significant drawback of such an approach is its time consuming nature. In this report, a single‐shot spiral imaging method, which combines spiral‐in and spiral‐out acquisitions along with embedded z‐shimming gradient, was proposed and implemented to achieve signal recovery without sacrificing temporal resolution. Results Using the proposed method, final images were shown in the ventral brain regions. The images were acquired with a throughput of 16 slices/second and demonstrated effectiveness and efficiency in signal recovery near air/tissue interfaces. Conclusion Uniform recovery can be achieved efficiently near air/tissue interfaces where susceptibility‐induced spatial gradients are pronounced. We anticipate that our method would be well suited for fMRI studies involving the ventral brain areas. J. Magn. Reson. Imaging 2003;18:389–395.