Joint myocardial T1 and T2 mapping
KeywordsSequence Diagram Simultaneous Estimation Joint Estimation Phantom Imaging Longitudinal Magnetization
Recent studies suggest that quantitative myocardial T1 mapping allows assessment of focal and diffuse fibrosis in the myocardium . Quantitative T2 mapping has also been proposed to overcome challenges associated with T2 weighted imaging . These maps are traditionally acquired with different sequences, necessitating image registration to evaluate them jointly. A sequence that can jointly estimate T1 and T2 maps has been proposed , but it requires multiple relaxation cycles, which necessitates a lengthy free-breathing acquisition. In , an alternative joint estimation sequence was proposed based on the inversion-recovery SSFP curve. In this study, we sought to develop a saturation-recovery based heart-rate independent sequence that can be acquired in a breath-hold and that allows for simultaneous estimation of quantitative T1 and T2 maps.
The T1 and T2 maps were estimated jointly by voxel-wise least squares fitting to a 4-parameter signal model, A (1- exp(-Tsatk/T1)) exp(-TEprepk/T2) + B. Phantom imaging of 14 vials with different T1/T2 values were performed and compared to inversion-recovery and CPMG spin-echo references, respectively. Breath-held in-vivo imaging was performed on 5 healthy adult subjects, and the maps were compared to SASHA T1 maps  and to T2 maps .
The proposed sequence allows for the simultaneous estimation of accurate and jointly registered quantitative T1 and T2 maps with similar accuracy and precision to saturation-based T1 mapping and to T2 mapping of same duration.
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