Zhou Zhengwei, Bez Maxim, Tawackoli Wafa, Giaconi Joseph, Sheyn Dmitriy, de Mel Sandra, Maya Marcel M, Pressman Barry D, Gazit Zulma, Pelled Gadi, Gazit Dan, Li Debiao
Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA.
Department of Bioengineering, University of California Los Angeles, Los Angeles, California, USA.
Magn Reson Med. 2016 Dec;76(6):1677-1683. doi: 10.1002/mrm.26457. Epub 2016 Sep 26.
Previous studies have associated low pH in intervertebral discs (IVDs) with discogenic back pain. The purpose of this study was to determine whether quantitative CEST (qCEST) MRI can be used to detect pH changes in IVDs in vivo.
The exchange rate k between glycosaminoglycan (GAG) protons and water protons was determined from qCEST analysis. Its dependence on pH value was investigated in GAG phantoms with varying pH and concentrations. The relationship between k and pH was studied further in vivo in a porcine model on a 3T MR scanner and validated using a pH meter. Sodium lactate was injected into the IVDs to induce various pH values within the discs ranging from 5 to 7.
Phantom and animal results revealed that k measured using qCEST MRI is highly correlated with pH level. In the animal studies, the relationship can be described as k =9.2 × 10 × 10 + 196.9, R = 0.7883.
The exchange rate between GAG and water protons determined from qCEST MRI is closely correlated with pH value. This technique has the potential to noninvasively measure pH in the IVDs of patients with discogenic pain. Magn Reson Med 76:1677-1683, 2016. © 2016 International Society for Magnetic Resonance in Medicine.
以往研究表明椎间盘（IVD）的低pH值与椎间盘源性背痛相关。本研究的目的是确定定量化学交换饱和转移（qCEST）磁共振成像（MRI）是否可用于在体检测IVD中的pH值变化。
通过qCEST分析确定糖胺聚糖（GAG）质子与水质子之间的交换率k。在不同pH值和浓度的GAG模型中研究其对pH值的依赖性。在3T MR扫描仪上的猪模型中进一步在体研究k与pH之间的关系，并使用pH计进行验证。向IVD中注射乳酸钠以诱导椎间盘内的各种pH值，范围为5至7。
模型和动物实验结果表明，使用qCEST MRI测量的k与pH水平高度相关。在动物研究中，这种关系可描述为k = 9.2×10×10 + 196.9，R = 0.7883。
由qCEST MRI确定的GAG与水质子之间的交换率与pH值密切相关。该技术有可能无创测量椎间盘源性疼痛患者IVD中的pH值。《磁共振医学》76:1677 - 1683, 2016。© 2016国际磁共振医学学会。
