Quantification techniques to minimize the effects of native T1 variation and B1 inhomogeneity in dynamic contrast-enhanced MRI of the breast at 3 T.

The variation of the native T₁ ( T₁₀) of different tissues and B₁ transmission-field inhomogeneity at 3 T are major contributors of errors in the quantification of breast dynamic contrast-enhanced MRI. To address these issues, we have introduced new enhancement indices derived from saturation-recovery snapshot-FLASH (SRSF) images. The stability of the new indices, i.e., the SRSF enhancement factor (EF_SRSF) and its simplified version (EF′_SRSF) with respect to differences in T₁₀ and B₁ inhomogeneity was compared against a typical index used in breast dynamic contrast-enhanced MRI, i.e., the enhancement ratio (ER), by using computer simulations. Imaging experiments with Gd-DTPA-doped gel phantoms and a female volunteer were also performed. A lower error was observed in the new indices compared to enhancement ratio in the presence of typical T₁₀ variation and B₁ inhomogeneity. At changes of relaxation rate (Δ R₁) of 8 s⁻¹, the differences between a T₁₀ of 1266 and 566 ms are <1, 12, and 58%, respectively, for EF_SRSF, EF′_SRSF, and ER, whereas differences of 20, 8, and 51%, respectively, result from a 50% B₁ field reduction at the same Δ R₁. These quantification techniques may be a solution to minimize the effect of T₁₀ variation and B₁ inhomogeneity on dynamic contrast-enhanced MRI of the breast at 3 T. Magn Reson Med, 2012. © 2011 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]