Improved Accuracy and Precision In Simultaneous Myocardial T1 and T2 mapping with Multi-Parametric SASHA (mSASHA)

Purpose: To develop and validate a multi-parametric SAturation-recovery single-SHot Acquisition (mSASHA) cardiac T1 and T2 mapping technique with high accuracy and precision in a single breath-hold. Methods: The mSASHA acquisition consists of 9 images in an 11 heartbeat breath-hold -- the first without preparation, 6 images with saturation recovery preparation, and 2 images with both saturation recovery and T2-preparation. T1 and T2 values were calculated using a 3-parameter model. mSASHA was validated in simulations and phantoms on a Siemens 3T Prisma scanner with comparison to a joint T1-T2 technique with a 4-parameter model. mSASHA values were compared to reference MOLLI, SASHA and T2p-bSSFP sequences in 10 healthy volunteers. Results: mSASHA had high accuracy compared to reference spin-echo measurements, with an average of -0.7+/-0.4% T1 error and -1.3+/-1.3% T2 error. mSASHA coefficient of variation (CoV) in phantoms for T1 was lower than MOLLI (0.7+/-0.1% vs 0.9+/-0.2%, p<0.01) and similar to reference T2p-bSSFP for T2 (1.4+/-0.6% vs 1.5+/-0.5%, p>0.05). In simulations, 3-parameter mSASHA fitting had higher precision than 4-parameter joint T1-T2 fitting for both T1 and T2. In-vivo myocardial mSASHA T1 was similar to conventional SASHA (1523+/-18 ms vs 1520+/-18 ms, p>0.05) with similar CoV to both MOLLI and SASHA (3.3+/-0.6% vs 3.1+/-0.6% and 3.3+/-0.5% respectively, p>0.05 for both). Myocardial mSASHA T2 values were 37.1+/-1.1 ms with similar precision to T2p-bSSFP (6.7+/-1.7% vs 6.0+/-1.6%, p>0.05). Conclusion: mSASHA provides high accuracy cardiac T1 and T2 quantification in a single breath-hold, with similar precision to reference MOLLI and linear T2p-bSSFP reference techniques.