A comparison of shimming techniques for optimizing fat suppression in MR mammography

Abstract

We evaluated the degree of inhomogeneities of fat suppression by using the fully automated three-dimensional breast shimming technique (Image Based-Smart: IB-Smart) and manual setting of a rectangular parallelepiped shim (volume shimming) in MR mammography. Information on breast shape was collected from 9 patients whose images were insufficiently fat-suppressed. A breast phantom made of a

Assessment of the Quality of Breast MR Imaging Using the Modified Dixon Method and Frequency-Selective Fat Suppression: A Phantom Study

“…However, fat suppression tends to be non-uniform, depending on the shape of the breasts even, when IBS is used. 3 In a previous report, when volume shimming was optimized, fat suppression became uniform. 3 …”

“…Breast concavities arise from shrinkage due to aging and lead to non-uniform fat suppression. 3 Hyperintensities on MR images may pose a problem in making a clinical diagnosis because when a hyperintensive area is covered with gadolinium (Gd) administration, identifying the mammary lesion could become difficult. To physically assess an image with fat suppression, a breast phantom that could easily reveal the influence of non-uniform fat suppression owing to the shape of concavities could be convenient and quantitative.…”

“…Therefore, we created an original breast phantom that could easily reveal the influence of non-uniform fat suppression based on clinical data. 3 …”

“…In a previous study, to obtain the center frequency, a bottle of copper sulfate was placed between the two breasts of the oil phantom. 3 However, to perform the high-precision physical verification, a lipid-content phantom with a dielectric constant and conductivity similar to that of the human body was needed. Volume shimming is useful to obtain an image with fat suppression.…”

Fat suppression techniques in breast magnetic resonance imaging: a critical comparison and state of the art

“…By default, the shimming or optimization of B 0 homogeneity is performed by the scanner over the entire large FOV instead of just the breast region. To achieve better B 0 uniformity over the breasts and surrounding regions, a localized shim volume covering only the breasts, the axilla, and the chest wall can be set up manually to optimize the B 0 homogeneity only for those regions and ignore other regions such as the heart and lungs, 52 At the same time, the adjustment of the scanner's center frequency should be optimized for the same regions as well. Most of the MR scanners allow users to manually check or confirm the setting of center frequency after the automatic adjustment is made.…”