Joint myocardial T1 and T2 mapping
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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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