Author(s)

Tomokazu Numano, Koji Hyodo, Naotaka Nitta, Junichi Hata, Nobuaki Iwasaki, Kazuhiro Homma

Department of Pediatrics, Ibaraki Prefectural University of Health Sciences, Ibaraki, Japan.
Department of Radiological Science, Tokyo Metropolitan University, Tokyo, Japan；National Institute of Advanced Industrial Science and Technology, Tsukuba, Japan.
Department of Radiology, The University of Tokyo Hospital, Tokyo, Japan.
National Institute of Advanced Industrial Science and Technology, Tsukuba, Japan.

Purpose: Commonly used diffusion weighted (DW) imaging such as DW spin echo (SE) type echo planar imaging (DW-SE-EPI) is known to be a snapshot-like acquisition and to have a relatively high signal-to-noise ratio. Spiral MRI sequence (SPIRAL) has characteristics similar to these of EPI, but it has rarely been used for diffusion-weighted imaging (DWI). In vivo DW-SPIRAL of the rat brain has almost never been reported. Our purpose in this study was to examine the potential of SE-type two-dimensional (2D) multi-shot spiral acquisition MRI for apparent diffusion coefficient (ADC) mapping of the rat brain in vivo. Materials and Methods: We made an SE-type DW-2D-spiral MRI sequence (DW-SPIRAL) which was prepared on a 2.0-T animal-experiment MR scanner. Comparing the phantom experimental result of DW-SPIRAL with the phantom experimental result of DW SE-type echo-planar imaging (DW-SE-EPI) and conventional DW spin echo imaging (DW-SE), we estimated the characteristics of DW-SPIRAL and assessed the clinical application of DW-SPIRAL in an animal experiment on the rat brain. Results: There was not much difference between the calculated water/glycerol phantom diffusion coefficient of DW-SPIRAL and the calculated diffusion coefficient of DW-SE. This result shows that the DW-SPIRAL sequence is appropriate for use in diffusion weighted imaging. There were fewer phantom image distortions and ghosting artifacts with DW-SPIRAL than with DW-SE-EPI, and this tendency was similar in the animal experiment on the rat brain. Conclusion: The DW-SPIRAL sequence had been successfully tested in phantom experiments and rat brain experiments. It has been demonstrated that the DW-SPIRAL sequence is capable of producing in vivo rat brain DWI.

Diffusion Weighted Imaging (DWI); Echo Planner Imaging (EPI); Spiral MRI Sequence; Apparent Diffusion Coefficient (ADC)

Numano, T. , Hyodo, K. , Nitta, N. , Hata, J. , Iwasaki, N. and Homma, K. (2014) Apparent Diffusion Coefficient Mapping Using a Multi-Shot Spiral MRI Sequence of the Rat Brain. Open Journal of Radiology, 4, 13-24. doi: 10.4236/ojrad.2014.41003.