Usefulness and Consideration of Multi-Band EPI using Simultaneous Multi-Slice for Diffusion Kurtosis Imaging at 1.5 Tesla Magnetic Resonance Imaging

Multiband Echo Planar Imaging (MB-EPI) was developed as a sequence for the Human Connectome Project of a large-scale clinical trial in the US. Recently, the concomitant use of MB-EPI with functional Magnetic Resonance Imaging (MRI) or diffusion MRI was reported; however, the combination of MB-EPI with Diffusional Kurtosis Imaging (DKI) has not been reported. We investigated the characteristics of Mean Kurtosis (MK) when MB-EPI was applied to DKI in a clinical 1.5 Tesla MRI. We obtained two DKIs, one of an MB-short when acquisition time was shortened and one of an MB-Motion Probing Gradient (MPG) with an increased number of directions at acquisition, similar to a conventional DKI by MB-EPI. These were compared to the reference DKI. An MK map or a quantitative value map of DKI and a tractography of a pyramidal tract were prepared. The latter was designated as the volume of interest, and a tract-specific analysis was conducted to detect statistically significant differences in MK values. When MB-EPI was used (MB-short and MB-MPG), the mean MK value of the pyramidal tract decreased compared to the reference DKI, and both were statistically significant from the DKI. Unlike other studies, we used a 12-channel receiver coil in a 1.5 Tesla MRI. Because the properties of the coil and MRI equipment adversely affect image reconstruction accuracy, this might have led to the statistical significance that we found. Equipment specifications in the imaging environment should be considered when carrying out quantitative evaluations.