In vivo Breast T1 Mapping at Ultra-Low Field (6.5 mT): Variable Flip Angle Method

Motivation: The fractional T1 differences between healthy and abnormal tissue are significant larger in the ultra-low-field (ULF) regime (<10 mT) compared to high field. Goal(s): Despite the challenges of imaging at ULF (predominately low SNR and spatial-temporal resolution), we demonstrate in vivo T1 mapping in the breast at 6.5 mT in 43 minutes. Approach: A variable flip angle (VFA) method with B1 correction was used. Results: T1 mapping of CuSO4 solutions showed an average T1 deviation <7% compared to reference T1 measurements. Breast phantom T1 mapping was also performed. Finally, this method was applied on two healthy female volunteers. Impact: This work explores ultra-low field T1 mapping as potential biomarker for low-cost breast imaging. We demonstrate the feasibility of quantitative T1 mapping of the human breast in healthy female volunteers at 6.5 mT using a variable flip angle method.