Department of Electrical and Computer Engineering, University of Calgary, Alberta, Canada.
Magn Reson Med. 2010 Feb;63(2):473-83. doi: 10.1002/mrm.22237.
Passive MRI is a promising approach to visualize catheters in guiding and monitoring endovascular intervention and may offer several clinical advantages over the current x-ray fluoroscopy "gold standard." Endovascular MRI has limitations, however, such as difficulty in visualizing catheters and insufficient temporal resolution. The multicycle projection dephaser method is a background signal suppression technique that improves the conspicuity of passive catheters by generating a sparse (i.e., catheter only) image. One approach to improve the temporal resolution is to undersample the k-space and then apply nonlinear methods, such as compressed sensing, to reconstruct the MR images. This feasibility study investigates the potential synergies between multicycle projection dephaser and compressed sensing reconstruction for real-time passive catheter tracking. The multicycle projection dephaser method efficiently suppressed the background signal, and compressed sensing allowed MR images to be reconstructed with superior catheter conspicuity and spatial resolution when compared to the more conventional zero-filling reconstruction approach. Moreover, compressed sensing allowed the shortening of total acquisition time (by up to 32 times) by vastly undersampling the k-space while simultaneously preserving spatial resolution and catheter conspicuity.
被动式 MRI 是一种很有前途的方法，可以可视化导管，用于指导和监测血管内介入治疗，并且可能比目前的 X 射线透视“金标准”具有几个临床优势。然而，血管内 MRI 具有一些局限性，例如难以可视化导管和时间分辨率不足。多周期投影去相器方法是一种背景信号抑制技术，通过生成稀疏（即仅导管）图像来提高被动式导管的显著性。提高时间分辨率的一种方法是欠采样 k 空间，然后应用非线性方法（例如压缩感知）来重建 MR 图像。这项可行性研究探讨了多周期投影去相器和压缩感知重建在实时被动式导管跟踪方面的潜在协同作用。多周期投影去相器方法能够有效地抑制背景信号，与更传统的零填充重建方法相比，压缩感知允许使用更高的导管显著性和空间分辨率重建 MR 图像。此外，压缩感知允许通过大幅欠采样 k 空间来缩短总采集时间（最多可达 32 倍），同时保持空间分辨率和导管显著性。
