Referentin: Evgeniya Kirilina

Title: The quest for the best: sensitivity and specificity of three novel EPI sequences in second level group analysis.

Abstract:

The design of optimized functional MRI (fMRI) pulse sequences requires a well-balanced compromise between contradicting demands such as whole brain coverage and high spatial resolution on the one hand, and high temporal resolution as well as high BOLD-signal sensitivity on the other hand.
In 3T fMRI a reasonable trade-off is provided by the currently most frequently used echo planar imaging (EPI) sequence with TR of about 2 s, and isotropic resolution of 3 mm.

Recently, several advanced EPI approaches with increased sensitivity, temporal and spatial resolution were developed. These are: combined multi-echo EPI, high resolution 3D modified EPI and ultra-fast dual-echo 3D-EPI imaging, which allows for TR shortening with unchanged spatial resolution. All three methods are available at DINE and were demonstrated to perform better in single subject fMRI using fixed-effects analysis compared to standard 2D single-shot EPI. However, until now it has not been studied in how far reduced variance at the single subject level provides improved performance in the second level group analysis where inter-subject variance usually dominates.

The current study bridges this gap by comparing the performance of above mentioned EPI approaches fMRI sequences on the second level analysis for brain activations in multiple brain areas and to clarify the benefits of these methods for different specific, neuroimaging application.