Electron paramagnetic resonance imaging of tumor hypoxia:: Enhanced spatial and temporal resolution for in vivo pO2 determination
Electron paramagnetic resonance imaging of tumor hypoxia:: Enhanced spatial and temporal resolution for in vivo pO2 determination
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DOI：
10.1002/mrm.20872
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发表时间：
2006-05-01
影响因子：
3.3
通讯作者：
Krishna, MC
中科院分区：
文献类型：
--
作者：
Matsumoto, K;Subramanian, S;Krishna, MC
电子顺磁共振 (EPR) 数据收集的时域 (TD) 模式提供了一种估计顺磁探针浓度和氧相关线宽 (LW) 的方法，以生成误差最小的 pO(2) 图。提出了一种基于 TD-EPR 应用的无创 pO(2) 成像方法，该方法使用氧诱导三芳基甲基 (TAM) 基自由基的 LW 展宽。图像中像素强度的衰减用于估计 T-2(*)，它与 pO(2) 成反比。严格分析每个像素中影响 T-2(*) 的因素，以提取溶解氧对 EPR 谱线展宽的贡献。获得了合适的实验和图像处理参数，以生成具有最小伪影的 pO(2) 图。通过使用多重梯度的新颖数据收集策略，图像伪影也被最小化。荷瘤小鼠的体模和体内成像结果验证了这种新的无创血氧测定方法。当前的成像协议实现了 2D pO(2) 映射的空间分辨率类似于 1.0 mm 的空间分辨率和类似于 9 s 的时间分辨率，可靠的氧气分辨率类似于 1 mmHg（气相中的氧气为 0.12%）。这项工作表明，体内血氧定量法可以具有良好的灵敏度、准确性以及高空间和时间分辨率。
The time-domain (TD) mode of electron paramagnetic resonance (EPR) data collection offers a means of estimating the concentration of a paramagnetic probe and the oxygen-dependent linewidth (LW) to generate pO(2) maps with minimal errors. A methodology for noninvasive pO(2) imaging based on the application of TD-EPR using oxygen-induced LW broadening of a triarylmethyl (TAM)-based radical is presented. The decay of pixel intensities in an image is used to estimate T-2(*), which is inversely proportional to pO(2). Factors affecting T-2(*) in each pixel are critically analyzed to extract the contribution of dissolved oxygen to EPR line-broadening. Suitable experimental and image-processing parameters were obtained to produce pO(2) maps with minimal artifacts. Image artifacts were also minimized with the use of a novel data collection strategy using multiple gradients. Results from a phantom and in vivo imaging of tumor-bearing mice validated this novel method of noninvasive oximetry. The current imaging protocols achieve a spatial resolution of similar to 1.0 mm and a temporal resolution of similar to 9 s for 2D pO(2) mapping, with a reliable oxygen resolution of similar to 1 mmHg (0.12% oxygen in gas phase). This work demonstrates that in vivo oximetry can be performed with good sensitivity, accuracy, and high spatial and temporal resolution.