Mousebed and anaesthetic delivery system for in vivo MRI

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Anderson, Melissa Sarah Lillian
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A 3D printed mousebed and anaesthetic device were designed and tested for use in a 7 T MRI machine. Images were obtained with samples in a radiofrequency (RF) coil inside the mousebed and with samples in the RF coil with makeshift holders to determine if the 3D printed mousebed could provide similar quality images and easier setup. Spin echo images were acquired of a 15 mL water phantom with the following parameters: field of view of 2cmx2cm, 64x64 matrix size, and slice thickness of 2mm. In theory, all voxels in the image within the water phantom should have the same signal intensity. In practice, there is a distribution of signal intensities due to magnetic field inhomogeneities and motion. The full width at half maximum (FWHM) of the distribution gives an indication of the image quality. With arbitrary values for signal intensities, comparisons of FWHM between images can be fairly made comparing the ratio of the FWHM and mean of the signal intensity. Oscillating gradient spin echo (OGSE) measurements were made of an unpreserved mouse head and the apparent diffusion coefficient (ADC) of the mouse brain was calculated to assess image quality of the type of image needed to infer axon diameters. The ADC of the mouse brain was found to be 0.2±0.1μm2/ms. The mousebed had a ratio of 0.11±0.02 and the plastic holder produced images with a ratio of 0.069±0.003. The mousebed and anaesthetic device satisfactorily centered the sample in the magnet without causing noticeable artifacts in the images. The anaesthetic device fit around the nose of the unpreserved mouse. We are now ready to test the device on a live mouse and proceed with measurements of axon diameters.
MRI, anaesthetic, mouse, RF coil, 3D printing