Results: 3

1.
Fig. 1

Fig. 1. From: Multi-Coil Shimming of the Mouse Brain.

Technical drawing (left) and experimental realization (right) of the MC setup for magnetic field homogenization of the mouse brain at 9.4 Tesla. The head of the mouse is surrounded by a Bolinger RF coil and the MC setup on the outside of the RF coil. The multi-coil's color coding represents an example set of coil-specific currents for the generation of a magnetic shim field in the mouse brain (as applied for static MC shimming, Fig. 2D). The individual circular coils are mounted with cable ties on the inside of an acrylic, cylindrical former. Solid mounting of the MC setup inside a scanner insert and the scanner bore allowed the predictable and accurate generation of shim fields in the mouse brain.

Christoph Juchem, et al. Magn Reson Med. ;66(3):893-900.
2.
Fig. 3

Fig. 3. From: Multi-Coil Shimming of the Mouse Brain.

Impact of the magnetic field homogeneity on the quality of gradient echo images in the mouse brain at 9.4 Tesla. Multi-slice axial images with a slice thickness of 500 μm were acquired at an echo time of 15 ms after static whole brain SH shimming (column 2), after static whole brain MC shimming (column 3) and after DMC shimming that was optimized over individual axial brain slices (column 4). Short echo time reference images of the selected 7 slices at 2 mm slice spacing are shown in the first column. The largely improved magnetic field homogeneity after global static and morevoer after slice-specific DMC shimming minimized local signal dropouts (white arrows) and provided significant signal gain over the entire brain compared to SH shimming.

Christoph Juchem, et al. Magn Reson Med. ;66(3):893-900.
3.
Fig. 2

Fig. 2. From: Multi-Coil Shimming of the Mouse Brain.

Magnetic field homogenization of the mouse brain at 9.4 Tesla with different shimming techniques. (A) A three-dimensional anatomical image of the head of the mouse allowed the extraction of the mouse brain (overlayed in purple). (B) Reference field map of the mouse brain in the absence of any shim fields. (C) Global static shimming with zero to second SH order terms allowed the removal of the shallow magnetic field components, however, multiple localized spots remained over the brain as well as transition bands connecting them. (D) Static whole brain MC shimming was able to suppress several hot spots e.g. in the olfactory bulb and to further flatten the central brain areas. (E) The dynamic application of slice-specific MC shim fields in individual axial slices removed almost all magnetic field inhomogeneity in the mouse brain and only minor variations remained in some voxels in the direct vicinity of the auditory cavities.

Christoph Juchem, et al. Magn Reson Med. ;66(3):893-900.

Supplemental Content

Recent activity

Your browsing activity is empty.

Activity recording is turned off.

Turn recording back on

See more...
Write to the Help Desk