Free-breathing self-gated continuous-IR spiral T1 mapping: Comparison of dual flip-angle and Bloch-Siegert B1-corrected techniques.
Free-breathing self-gated continuous-IR spiral T1 mapping: Comparison of dual flip-angle and Bloch-Siegert B1-corrected techniques.
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DOI：
10.1002/mrm.29269
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发表时间：
2022-09
影响因子：
3.3
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建立一种用于螺旋T1标测的B1矫正单翻角连续采集策略，并与已有的双翻角方法进行比较。数据是使用螺旋形轨迹连续采集的，该轨迹在时间上以黄金角度旋转。在最初的2 S期间，应用非共振费米射频脉冲来产生Bloch-Siegert位移B1图，并通过每4 S施加一个反转RF脉冲来获取后续数据以创建T1*图。最终的T1图是通过使用考虑切片轮廓效应的查找表从B1和T1*图生成的，从而产生更准确的T1值。T1值与反转恢复(IR)自旋回波(仅限幻影)、Molli、饱和恢复单次激发采集(SAHA)以及先前提出的双翻转角结果进行了比较。这一策略在一个幻影和25名人类受试者中进行了评估。在体模实验中，该方法与红外自旋回波实验结果吻合较好。对于活体研究，所提出的技术和先前所提出的双翻转角方法更类似于Sasha结果而不是Molli结果。与先前提出的双激励翻转角度技术相比，经B1校正的单翻转角T1映射在自由呼吸、连续IR螺旋采集中成功获取了B1和T1映射图，提供了一种使用连续Look-Locker采集来测量T1的精度更高的方法。
To develop a B1‐corrrected single flip‐angle continuous acquisition strategy with free‐breathing and cardiac self‐gating for spiral T1 mapping, and compare it to a previous dual flip‐angle technique. Data were continuously acquired using a spiral‐out trajectory, rotated by the golden angle in time. During the first 2 s, off‐resonance Fermi RF pulses were applied to generate a Bloch‐Siegert shift B1 map, and the subsequent data were acquired with an inversion RF pulse applied every 4 s to create a T1* map. The final T1 map was generated from the B1 and the T1* maps by using a look‐up table that accounted for slice profile effects, yielding more accurate T1 values. T1 values were compared to those from inversion recovery (IR) spin echo (phantom only), MOLLI, SAturation‐recovery single‐SHot Acquisition (SASHA), and previously proposed dual flip‐angle results. This strategy was evaluated in a phantom and 25 human subjects. The proposed technique showed good agreement with IR spin‐echo results in the phantom experiment. For in‐vivo studies, the proposed technique and the previously proposed dual flip‐angle method were more similar to SASHA results than to MOLLI results. B1‐corrected single flip‐angle T1 mapping successfully acquired B1 and T1 maps in a free‐breathing, continuous‐IR spiral acquisition, providing a method with improved accuracy to measure T1 using a continuous Look‐Locker acquisition, as compared to the previously proposed dual excitation flip‐angle technique.