Abstract

PURPOSE: To quantify B?1+ variation across the breasts and to evaluate the accuracy of precontrast T(1) estimation with and without B?1+ variation in breast MRI patients at 3 Tesla (T). MATERIALS AND METHODS: B?1+ and variable flip angle (VFA) T(1) mapping were included in our dynamic contrast-enhanced (DCE) breast imaging protocol to study a total of 25 patients on a 3.0T GE MR 750 system. We computed precontrast T(1) relaxation in fat, which we assumed to be consistent across a cohort of breast imaging subjects, with and without compensation for B?1+ variation. The mean and standard deviation of B?1+ and T(1) values were calculated for statistical data analysis. RESULTS: Our measurements showed a consistent B?1+ field difference between the left and right breasts. The left breast has an average 15.4% higher flip angle than the prescribed flip angle, and the right breast has an average 17.6% lower flip angle than the prescribed flip angle. This average 33% flip angle difference, which can be vendor and model specific, creates a 52% T(1) estimation bias in fat between breasts using the VFA T(1) mapping technique. The T(1) variation is reduced to 7% by including B?1+ correction. CONCLUSION: We have shown that severe B?1+ variation over the breasts can cause a substantial error in T(1) estimation between the breasts, in VFA T(1) maps at 3T, but that compensating for these variations can considerably improve accuracy of T(1) measurements, which can directly benefit quantitative breast DCE-MRI at 3T. J. Magn. Reson. Imaging 2012;. © 2012 Wiley Periodicals, Inc.

View details for DOI 10.1002/jmri.23996

View details for Web of Science ID 000323205300024

View details for PubMedID 23292822

View details for PubMedCentralID PMC3620726