Compressed sensing to accelerate magnetic resonance spectroscopic imaging: evaluation and application to 23Na-imaging of mouse hearts.
Compressed sensing to accelerate magnetic resonance spectroscopic imaging: evaluation and application to 23Na-imaging of mouse hearts.
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DOI：
10.1186/s12968-015-0149-6
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发表时间：
2015-06-15
期刊：
影响因子：
--
通讯作者：
Schneider JE
中科院分区：
文献类型：
--
作者：
Maguire ML;Geethanath S;Lygate CA;Kodibagkar VD;Schneider JE
磁共振波谱成像(MRSI)在临床和临床前的非侵入性生化评估中具有广泛的适用性，但扫描时间较长。压缩传感技术(CS)已成功应用于临床1H磁共振成像，但对其在常规化学位移成像中的应用缺乏详细的评价。在这里，我们评估了CS加速MRSI的性能，并将其具体应用于9.4℃下在活体小鼠心脏上加速23Na-MRSI。合成体模数据代表了小鼠胸部的简化切片，用于评估CS重建在不同欠采样水平、分辨率和信噪比(SNR)下的保真度。相对于无噪声傅立叶变换(FT)数据，确定了来自隔室内的信号的幅度以及来自隔室外部的信号污染。模拟结果随后在模体和三个活体小鼠心脏上得到了实验验证。CS重建的MRSI数据相对于来自全采样FT重建情况的绝对信号强度线性缩放(R2 &> 0.8，p-Value <； 0.001)。较高的加速系数会导致重建光谱的去噪，但也会增加隔室边界的模糊，特别是在较低的空间分辨率下。分辨率和信噪比的提高减少了跨舱污染，并产生了更接近FT数据的信号幅度。可在~23分钟内获得概念验证的高分辨率、3倍加速的小鼠心肌~(23)Na幅值图。相对信号幅度(即代谢物比率)和代谢物浓度的绝对量化可以通过最多5倍欠采样、CS重建的MRSI来准确确定。虽然这项工作集中在小鼠心脏23Na-MRSI上，但结果同样适用于其他核和组织(例如脑中的1H MRSI)。MRSI扫描时间的显著减少将减轻受试者的负担，增加扫描仪的吞吐量，并可能为(临床前)代谢研究开辟新的途径。
Magnetic Resonance Spectroscopic Imaging (MRSI) has wide applicability for non-invasive biochemical assessment in clinical and pre-clinical applications but suffers from long scan times. Compressed sensing (CS) has been successfully applied to clinical 1H MRSI, however a detailed evaluation of CS for conventional chemical shift imaging is lacking. Here we evaluate the performance of CS accelerated MRSI, and specifically apply it to accelerate 23Na-MRSI on mouse hearts in vivo at 9.4 T. Synthetic phantom data representing a simplified section across a mouse thorax were used to evaluate the fidelity of the CS reconstruction for varying levels of under-sampling, resolution and signal-to-noise ratios (SNR). The amplitude of signals arising from within a compartment, and signal contamination arising from outside the compartment relative to noise-free Fourier-transformed (FT) data were determined. Simulation results were subsequently verified experimentally in phantoms and in three mouse hearts in vivo. CS reconstructed MRSI data are scaled linearly relative to absolute signal intensities from the fully-sampled FT reconstructed case (R2 > 0.8, p-value < 0.001). Higher acceleration factors resulted in a denoising of the reconstructed spectra, but also in an increased blurring of compartment boundaries, particularly at lower spatial resolutions. Increasing resolution and SNR decreased cross-compartment contamination and yielded signal amplitudes closer to the FT data. Proof-of-concept high-resolution, 3-fold accelerated 23Na-amplitude maps of murine myocardium could be obtained within ~23 mins. Relative signal amplitudes (i.e. metabolite ratios) and absolute quantification of metabolite concentrations can be accurately determined with up to 5-fold under-sampled, CS-reconstructed MRSI. Although this work focused on murine cardiac 23Na-MRSI, the results are equally applicable to other nuclei and tissues (e.g. 1H MRSI in brain). Significant reduction in MRSI scan time will reduce the burden on the subject, increase scanner throughput, and may open new avenues for (pre-) clinical metabolic studies.
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