Imaging Near Metal: The Impact of Extreme Static Local Field Gradients on Frequency Encoding Processes
Imaging Near Metal: The Impact of Extreme Static Local Field Gradients on Frequency Encoding Processes
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DOI：
10.1002/mrm.24862
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发表时间：
2014-06-01
影响因子：
3.3
通讯作者：
Hargreaves, Brian A.
中科院分区：
文献类型：
--
作者：
Koch, Kevin M.;King, Kevin F.;Hargreaves, Brian A.
随着三维多光谱成像（3D-MSI）方法的发展，金属器件直接附近的磁共振成像能力已经大大提高。当在金属硬件附近成像时，3D-MSI技术中的大块图像失真被降低到单像素水平。然而，通常使用的MSI技术最终受到频率编码过程的限制，并揭示了一类尚未正式分析的基于残余强度的磁化率伪影。方法利用实验测量和模拟技术研究金属植入体引起的局部磁场梯度及其对频率编码过程的影响。这些梯度对3D-MSI方法的具体后果也使用经验和模拟方法进行了分析。结果实验和模拟测量结果之间的密切一致清楚地表明，强局部梯度对金属植入物附近频率编码成像能力的影响。结论3d - msi技术可以显著增强金属植入物附近的磁共振成像能力。然而，强局部静场梯度会产生残余伪影，其直接缓解最终受到频率编码处理的限制。3D编码策略的应用或额外的后处理可能需要进一步减少金属植入物附近多光谱图像中的残留伪影。中华医学杂志（英文版），2014。(c) 2013 Wiley Periodicals, Inc.；
PurposeMagnetic resonance imaging capabilities in the direct vicinity of metallic devices have substantially improved with the recent development of three-dimensional multispectral imaging (3D-MSI) methods. When imaging near metallic hardware, the bulk image distortions in 3D-MSI techniques are reduced to the single-pixel level. However, commonly utilized MSI techniques are ultimately limited by frequency-encoding processes and reveal a class of residual intensity-based susceptibility artifacts that have yet to be formally analyzed.MethodsEmpirical measurements and simulation techniques are utilized to study the static local magnetic field gradients induced by metal implants and their general impact on frequency-encoding processes. The specific consequences of these gradients on 3D-MSI approaches are also analyzed using empirical and simulated approaches.ResultsClose agreements between empirical and simulated measurements clearly demonstrate the effects of strong local gradients on frequency-encoded imaging capabilities near metallic implants.Conclusions3D-MSI techniques can enable substantially enhanced magnetic resonance imaging capabilities near metallic implants. However, strong local static field gradients generate residual artifacts whose direct mitigation are ultimately limited by frequency encoding processes. Applications of 3D encoding strategies or additional post processing may be required to further reduce residual artifacts in multispectral images near metal implants. Magn Reson Med 71:2024-2034, 2014. (c) 2013 Wiley Periodicals, Inc.