Magnetization transfer in magnetic resonance fingerprinting
Magnetization transfer in magnetic resonance fingerprinting
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DOI：
10.1002/mrm.28096
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发表时间：
2019-11-25
影响因子：
3.3
通讯作者：
Cloos, Martijn A.
中科院分区：
文献类型：
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作者：
Hilbert, Tom;Xia, Ding;Cloos, Martijn A.
目的研究半固体自旋池与自由池相互作用的磁化转移（MT）在磁共振指纹识别（MRF）中的影响。方法通过模拟和模拟实验，研究MT对MRF信号的影响及其对T-1和T-2估计的潜在影响。随后，利用一个实现非共振MT脉冲的MRF序列和一个包含MT维度的字典（由合并两池模型生成），除B1+、T-1和T-2值外，还用于估计分数池大小。在人脑中对所提出的方法进行了评估。结果模拟和模拟实验表明，从交联牛血清样品中获得的磁共振信号受到MT的影响。使用基于MT模型的字典，可以获得模拟和获取的磁共振信号之间更好的匹配（NRMSE为1.3% vs. 4.7%）。加入非共振MT脉冲可以提高MT与T-1和T-2的分化。体内实验结果显示，MT会影响来自白质（分数池大小约为16%）和灰质（分数池大小约为10%）的MRF信号。此外，如果考虑到MT，可以在白质中观察到更长的T-1（类似于1060 ms vs. 860 ms）和T-2值（类似于47 ms vs. 35 ms）。结论我们的实验证明了MT对MRF定量T-1和T-2的潜在影响。包含MT效应的模型可以提高估计松弛参数的准确性，并允许对分数池大小进行量化。
Purpose To study the effects of magnetization transfer (MT, in which a semi-solid spin pool interacts with the free pool), in the context of magnetic resonance fingerprinting (MRF). Methods Simulations and phantom experiments were performed to study the impact of MT on the MRF signal and its potential influence on T-1 and T-2 estimation. Subsequently, an MRF sequence implementing off-resonance MT pulses and a dictionary with an MT dimension, generated by incorporating a two-pool model, were used to estimate the fractional pool size in addition to the B1+, T-1, and T-2 values. The proposed method was evaluated in the human brain. Results Simulations and phantom experiments showed that an MRF signal obtained from a cross-linked bovine serum sample is influenced by MT. Using a dictionary based on an MT model, a better match between simulations and acquired MR signals can be obtained (NRMSE 1.3% vs. 4.7%). Adding off-resonance MT pulses can improve the differentiation of MT from T-1 and T-2. In vivo results showed that MT affects the MRF signals from white matter (fractional pool-size similar to 16%) and gray matter (fractional pool-size similar to 10%). Furthermore, longer T-1 (similar to 1060 ms vs. similar to 860 ms) and T-2 values (similar to 47 ms vs. similar to 35 ms) can be observed in white matter if MT is accounted for. Conclusion Our experiments demonstrated a potential influence of MT on the quantification of T-1 and T-2 with MRF. A model that encompasses MT effects can improve the accuracy of estimated relaxation parameters and allows quantification of the fractional pool size.