2D sodium MRI of the human calf using half-sinc excitation pulses and compressed sensing
2D sodium MRI of the human calf using half-sinc excitation pulses and compressed sensing
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DOI：
10.1002/mrm.29841
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发表时间：
2023-10-05
影响因子：
3.3
通讯作者：
Steeden，Jennifer A.
中科院分区：
文献类型：
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作者：
Baker，Rebecca R.;Muthurangu，Vivek;Steeden，Jennifer A.
目的钠离子MRI可用于定量体内组织钠离子浓度（TSC），但需要UTE序列来捕获快速衰减的信号。2D MRI能够实现高平面内分辨率，但通常具有较长的TE。半正弦激励可以启用UTE;但是，需要两倍的读数。扫描时间可以通过减少信号平均值（NSA）的数量来最小化，但以SNR为代价。我们建议使用压缩感知（CS），以加速2D half-sinc收购，同时保持SNR和TSC.MethodsEx体内和体内TSC之间的2D螺旋序列与全sinc（TE = 0.73毫秒，扫描时间为10分钟）和half-sinc激励（TE = 0.23毫秒，扫描时间为10分钟）进行了比较，与150个NSA。离体，将这些与参考3D序列（TE = 0.22 ms，扫描时间约24 min）进行比较。为了研究缩短2D扫描时间，使用较少的NSA回顾性重建半正弦数据，将非均匀快速傅立叶变换与CS进行比较。结果TSC和图像质量进行了比较，参考150个NSAs非均匀快速傅立叶变换images.ResultsTSC是显着高于从半正弦比全正弦采集，离体和体内。离体，半正弦数据与参考3D序列更接近匹配，表明准确性提高。计算机模拟证实，这是由于较短的TE最大限度地减少了体模和组织之间的弛豫差异引起的偏倚。CS成功应用于体内半正弦数据，使用≥50个NSA维持TSC和图像质量（估计的SNR、边缘清晰度和定性指标）。结论采用半正弦激励和CS的2D钠MRI经过验证，能够实现分辨率为2.25 × 2.25 mm 2的TSC定量，扫描时间≤5 min。
PurposeSodium MRI can be used to quantify tissue sodium concentration (TSC) in vivo; however, UTE sequences are required to capture the rapidly decaying signal. 2D MRI enables high in‐plane resolution but typically has long TEs. Half‐sinc excitation may enable UTE; however, twice as many readouts are necessary. Scan time can be minimized by reducing the number of signal averages (NSAs), but at a cost to SNR. We propose using compressed sensing (CS) to accelerate 2D half‐sinc acquisitions while maintaining SNR and TSC.MethodsEx vivo and in vivo TSC were compared between 2D spiral sequences with full‐sinc (TE = 0.73 ms, scan time ≈ 5 min) and half‐sinc excitation (TE = 0.23 ms, scan time ≈ 10 min), with 150 NSAs. Ex vivo, these were compared to a reference 3D sequence (TE = 0.22 ms, scan time ≈ 24 min). To investigate shortening 2D scan times, half‐sinc data was retrospectively reconstructed with fewer NSAs, comparing a nonuniform fast Fourier transform to CS. Resultant TSC and image quality were compared to reference 150 NSAs nonuniform fast Fourier transform images.ResultsTSC was significantly higher from half‐sinc than from full‐sinc acquisitions, ex vivo and in vivo. Ex vivo, half‐sinc data more closely matched the reference 3D sequence, indicating improved accuracy. In silico modeling confirmed this was due to shorter TEs minimizing bias caused by relaxation differences between phantoms and tissue. CS was successfully applied to in vivo, half‐sinc data, maintaining TSC and image quality (estimated SNR, edge sharpness, and qualitative metrics) with ≥50 NSAs.Conclusion2D sodium MRI with half‐sinc excitation and CS was validated, enabling TSC quantification with 2.25 × 2.25 mm2resolution and scan times of ≤5 mins.