B-1 Transmission-Field Inhomogeneity and Enhancement Ratio Errors in Dynamic Contrast-Enhanced MRI (DCE-MRI) of the Breast at 3T

Che A. Azlan, Pierluigi Di Giovanni, Trevor S. Ahearn, Scott I. K. Semple, Fiona J. Gilbert, Thomas W. Redpath

Research output: Contribution to journalArticlepeer-review

Abstract

Purpose: To quantify B-1 transmission-field inhomogeneity in breast imaging of normal volunteers at 3T using 3D T-1-weighted spoiled gradient echo and to assess the resulting errors in enhancement ratio (ER) measured in dynamic contrast-enhanced MRI (DCE-MRI) studies of the breast.

Materials and Methods: A total of 25 volunteers underwent breast imaging at 3T and the B-1 transmission-fields were mapped. Gel phantoms that simulate pre- and postcontrast breast tissue T-1 were developed. The effects of B-1-field inhomogeneity on ER, as measured using a 3D spoiled gradient echo sequence, were investigated by computer simulation and experiments on gel phantoms.

Results: It was observed that by using the patient orientation and MR scanner employed in this study. the B-1 transmission-field field is always reduced toward the volunteer's right side. The median B-1-field in the right breast is reduced around 40% of the expected B-1-field. For some volunteers the amplitude was reduced by more than 50%. Computer simulation and experiment showed that a reduction in B-1-field decreases ER. This reduction increases with both B-1-field error and contrast agent uptake.

Conclusion: B-1 transmission-field inhomogeneity is a critical issue in breast imaging at 3T and causes errors in quantifying ER. These errors would be sufficient to reduce the conspicuity of a malignant lesion and could result in reduced sensitivity for cancer detection.

Original languageEnglish
Pages (from-to)234-239
Number of pages6
JournalJournal of Magnetic Resonance Imaging
Volume31
Issue number1
DOIs
Publication statusPublished - Jan 2010

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