Accurate T-1 Mapping for Oxygen-Enhanced MRI in the Mouse Lung Using a Segmented Inversion-Recovery Ultrashort Echo-Time Sequence

PurposeA 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. MethodsNumerical 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. ResultsThe 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. ConclusionSegmented inversion-recovery ultrashort echo-time provides accurate, high resolution T-1 mapping of the lung parenchyma. Magn Reson Med 71:2180-2185, 2014. (c) 2013 Wiley Periodicals, Inc.