Implications of respiratory motion for the quantification of 2D MR spectroscopic imaging data in the abdomen.
Implications of respiratory motion for the quantification of 2D MR spectroscopic imaging data in the abdomen.
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DOI：
10.1088/0031-9155/45/8/304
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发表时间：
2000-08
影响因子：
3.5
通讯作者：
A J Schwarz;M O Leach
中科院分区：
文献类型：
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作者：
A J Schwarz;M O Leach
在存在呼吸运动的情况下采集腹部或乳房中的磁共振光谱成像（MRSI）研究。这修改了点扩散函数（PSF），从而修改了重建的光谱。我们评估了定量的影响，周期性和非周期性运动的光谱定位MRSI。伪信号变化，包括体素固有信号的修改和其他地方产生的伪信号，主要取决于相对于体素尺寸的运动幅度。对于简谐运动（SHM），准周期运动和随机位移，观察到类似的运动振幅依赖性。没有系统的依赖于SHM的周期或初始相位或阵列的大小。也没有显着的变化与运动方向相对于内部和外部的相位编码方向。在20个乳腺和腹部肿瘤的测量偏移范围内，70%移动≤ 5 mm，而30%移动6-23 mm。肠道中的隔膜和脂肪组织通常移动约15-20 mm。虽然小于体素尺寸一半的肿瘤/器官偏移基本上不会影响原生信号，但在1H研究中，强脂质信号的出血将是个问题。因此，腹部MRSI研究，即使是相对固定良好的肿瘤，也可能受益于增加呼吸触发或其他运动补偿策略。
Magnetic resonance spectroscopic imaging (MRSI) studies in the abdomen or breast are acquired in the presence of respiratory motion. This modifies the point spread function (PSF) and hence the reconstructed spectra. We evaluated the quantitative effects of both periodic and aperiodic motion on spectra localized by MRSI. Artefactual signal changes, both the modification of native to a voxel and spurious signals arising elsewhere, depend primarily upon the motion amplitude relative to the voxel dimension. A similar dependence on motion amplitude was observed for simple harmonic motion (SHM), quasi-periodic motion and random displacements. No systematic dependence upon the period or initial phase of SHM or on the array size was found. There was also no significant variation with motion direction relative to the internal and external phase-encoding directions. In measured excursion ranges of 20 breast and abdominal tumours, 70% moved < or = 5 mm, while 30% moved 6-23 mm. The diaphragm and fatty tissues in the gut typically moved approximately 15-20 mm. While tumour/organ excursions less than half the voxel dimension do not substantially affect native signals, the bleeding in of strong lipid signals will be problematic in 1H studies. MRSI studies in the abdomen, even of relatively well-anchored tumours, are thus likely to benefit from the addition of respiratory triggering or other motion compensation strategies.