Accurate T1 mapping for oxygen‐enhanced MRI in the mouse lung using a segmented inversion‐recovery ultrashort echo‐time sequence

Abstract

A segmented inversion-recovery module combined with the 2D ultrashort echo time radial technique is proposed that allows accurate pixel level T(1) mapping of mouse lung in vivo. Numerical simulations were performed to estimate T(1) measurement accuracy and precision versus flip angle and signal-to-noise ratio. Phantom measurements were used for protocol validation, where the segmented inversion-recovery ultrashort echo-time sequence was compared with the reference technique (inversion-recovery rapid acquisition with refocused echoes). The in vivo experiments were carried out on free-breathing C57 mice (n = 10), breathing first air and then oxygen. The simulations demonstrated the high potential of the technique for accurate and precise T(1) assessment. Phantom experiments showed good agreement for T(1) values measured with segmented inversion-recovery ultrashort echo-time and the reference technique. The in vivo experiment demonstrated the utility of the technique in oxygen-enhanced assessment, where small T(1) changes were detected with high precision. Segmented inversion-recovery ultrashort echo-time provides accurate, high resolution T(1) mapping of the lung parenchyma.