Wallace Tess E, Manavaki Roido, Graves Martin J, Patterson Andrew J, Gilbert Fiona J
Department of Radiology, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK. NIHR Cambridge Biomedical Research Centre, Cambridge Biomedical Campus, Cambridge, UK.
Phys Med Biol. 2017 Jan 7;62(1):127-145. doi: 10.1088/1361-6560/62/1/127. Epub 2016 Dec 14.
Physiological fluctuations are expected to be a dominant source of noise in blood oxygenation level-dependent (BOLD) magnetic resonance imaging (MRI) experiments to assess tumour oxygenation and angiogenesis. This work investigates the impact of various physiological noise regressors: retrospective image correction (RETROICOR), heart rate (HR) and respiratory volume per unit time (RVT), on signal variance and the detection of BOLD contrast in the breast in response to a modulated respiratory stimulus. BOLD MRI was performed at 3 T in ten volunteers at rest and during cycles of oxygen and carbogen gas breathing. RETROICOR was optimized using F-tests to determine which cardiac and respiratory phase terms accounted for a significant amount of signal variance. A nested regression analysis was performed to assess the effect of RETROICOR, HR and RVT on the model fit residuals, temporal signal-to-noise ratio, and BOLD activation parameters. The optimized RETROICOR model accounted for the largest amount of signal variance ([Formula: see text] = 3.3 ± 2.1%) and improved the detection of BOLD activation (P = 0.002). Inclusion of HR and RVT regressors explained additional signal variance, but had a negative impact on activation parameter estimation (P < 0.001). Fluctuations in HR and RVT appeared to be correlated with the stimulus and may contribute to apparent BOLD signal reactivity.
在用于评估肿瘤氧合作用和血管生成的血氧水平依赖（BOLD）磁共振成像（MRI）实验中，生理波动预计是噪声的主要来源。这项研究调查了各种生理噪声回归器：回顾性图像校正（RETROICOR）、心率（HR）和单位时间呼吸量（RVT）对信号方差以及乳腺中BOLD对比响应调制呼吸刺激检测的影响。在3T场强下，对10名志愿者在静息状态以及氧气和二氧化碳混合气体呼吸周期中进行BOLD MRI检查。使用F检验对RETROICOR进行优化，以确定哪些心脏和呼吸相位项占显著量的信号方差。进行了嵌套回归分析，以评估RETROICOR、HR和RVT对模型拟合残差、时间信噪比和BOLD激活参数的影响。优化后的RETROICOR模型占信号方差的最大量（[公式：见正文] = 3.3 ± 2.1%），并改善了BOLD激活的检测（P = 0.002）。纳入HR和RVT回归器解释了额外的信号方差，但对激活参数估计有负面影响（P < 0.001）。HR和RVT的波动似乎与刺激相关，并可能导致明显的BOLD信号反应性。
