Unit of Academic Radiology, University of Sheffield, Sheffield, UK.
Magn Reson Med. 2010 Apr;63(4):1059-69. doi: 10.1002/mrm.22302.
In this work, the application of compressed sensing techniques to the acquisition and reconstruction of hyperpolarized (3)He lung MR images was investigated. The sparsity of (3)He lung images in the wavelet domain was investigated through simulations based on fully sampled Cartesian two-dimensional and three-dimensional (3)He lung ventilation images, and the k-spaces of 2D and 3D images were undersampled randomly and reconstructed by minimizing the L1 norm. The simulation results show that temporal resolution can be readily improved by a factor of 2 for two-dimensional and 4 to 5 for three-dimensional ventilation imaging with (3)He with the levels of signal to noise ratio (SNR) (approximately 19) typically obtained. The feasibility of producing accurate functional apparent diffusion coefficient (ADC) maps from undersampled data acquired with fewer radiofrequency pulses was also demonstrated, with the preservation of quantitative information (mean ADC(cs) approximately mean ADC(full) approximately 0.16 cm(2) sec(-1)). Prospective acquisition of 2-fold undersampled two-dimensional (3)He images with a compressed sensing k-space pattern was then demonstrated in a healthy volunteer, and the results were compared to the equivalent fully sampled images (SNR(cs) = 34, SNR(full) = 19).
本工作研究了压缩感知技术在超极化 (3)He 肺部磁共振成像的采集和重建中的应用。通过基于完全采样笛卡尔二维和三维 (3)He 肺部通气图像的模拟,研究了 (3)He 肺部图像在小波域中的稀疏性,并且随机对二维和三维图像的 k 空间进行欠采样,并通过最小化 L1 范数来重建。模拟结果表明,对于二维和三维通气成像,信号噪声比 (SNR) (约 19)通常较高的情况下,时间分辨率可以轻易地提高 2 倍因子。还证明了从具有较少射频脉冲采集的欠采样数据中生成准确的功能表观扩散系数 (ADC) 图的可行性,同时保留定量信息(平均 ADC(cs) 约等于平均 ADC(full) 约等于 0.16 cm(2) sec(-1))。然后在健康志愿者中进行了前瞻性采集具有压缩感知 k 空间模式的 2 倍欠采样二维 (3)He 图像,并将结果与等效的完全采样图像进行了比较(SNR(cs) = 34,SNR(full) = 19)。
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