This subproject is one of many research subprojects utilizing theresources provided by a Center grant funded by NIH/NCRR. The subproject andinvestigator (PI) may have received primary funding from another NIH source,and thus could be represented in other CRISP entries. The institution listed isfor the Center, which is not necessarily the institution for the investigator.Introduction: One problem in high resolution fMRI studies is the low SNR of images. Although using a surface coil could increase the SNR, it will limit the studies to a certain area of the brain. However there are cases where high resolution fMRI over the whole brain is desired which will result in a large number of slices. The 3D method (1,2), as an alternative, has the benefit of increased SNR compared to the multi-slice 2D methods especially when the number of slices is large. The temporal resolution is very poor since multi-shot spirals are used to achieve the high in-plane resolution. However, using UNFOLD (3) technique it can be improved to a level which is equivalent to that of a single-shot spiral.Methods and Discussion: Experiments were performed on normal volunteers using a 3 Tesla whole-body scanner with a small head coil. A 3D 2-shot stack-of-spirals trajectory was used to cover the k-space. In the slab-select direction, the excited slab thickness was 93mm with a FOV of 96mm and slice thickness of 1.5mm. Two end slices were discarded to reduce aliasing artifacts. The in-plane trajectory is a single shot, uniform density spiral with FA/TE/FOV/MAT = 20?/30ms/22cm/128*128. Therefore the voxel size is 1.5mm 1.7mm 1.7mm. 80 time frames were collected during the functional scan with a block design of 20s-on/20s-off and sensory task. UNFOLD technique was used to produce a separate time frame for each interleaved spiral. Therefore altogether 160 time frames were produced with an effective temporal resolution of 5.12s. Results did show activations in the motor, auditory and visual areas.
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