Practical methods for improving B1+ homogeneity in 3 Tesla breast imaging.
| Publication Type | Academic Article |
| Authors | Winkler S, Rutt B |
| Journal | J Magn Reson Imaging |
| Volume | 41 |
| Issue | 4 |
| Pagination | 992-9 |
| Date Published | 04/10/2014 |
| ISSN | 1522-2586 |
| Keywords | Algorithms, Artifacts, Breast, Image Enhancement, Image Interpretation, Computer-Assisted, Magnetic Resonance Imaging |
| Abstract | PURPOSE: To improve image contrast and B1+ field homogeneity in 3 Tesla (T) breast MR. MATERIALS AND METHODS: Two practical B1+ shimming methods for 3T breast MR are presented; low-cost passive shimming using local pads of high dielectric permittivity (εr from 0 to 100), and two-channel radiofrequency (RF) shimming (adjusting Q-I amplitude ratios and phase differences of 0 to -4 dB and 90 to 45 degrees), as well as a combination of both methods. The technique has been studied both in simulation using a numerical body model with added mammary tissue and in vivo in six subjects. RESULTS: Large improvements are observed with both methods, leading to a decrease in left-right B1+ asymmetry ratio of 1.24 to 1.00 (simulation) and from 1.26 to 1.01 (in vivo). RF safety was not adversely affected. CONCLUSION: Both RF shimming and dielectric shimming were shown to improve inhomogeneity in the B1+ field in 3T breast MR. |
| DOI | 10.1002/jmri.24635 |
| PubMed ID | 24723508 |
| PubMed Central ID | PMC4831901 |