Liu Qi, Tawackoli Wafa, Pelled Gadi, Fan Zhaoyang, Jin Ning, Natsuaki Yutaka, Bi Xiaoming, Gart Avrom, Bae Hyun, Gazit Dan, Li Debiao
Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA; Department of Biomedical Engineering, Northwestern University, Chicago, Illinois, USA.
Magn Reson Med. 2015 Mar;73(3):1196-205. doi: 10.1002/mrm.25186. Epub 2014 Apr 2.
Low pH is associated with intervertebral disc (IVD)-generated low back pain (LBP). The purpose of this work was to develop an in vivo pH level-dependent magnetic resonance imaging (MRI) method for detecting discogenic LBP, without using exogenous contrast agents.
The ratio of R1ρ dispersion and chemical exchange saturation transfer (CEST) (RROC) was used for pH-level dependent imaging of the IVD while eliminating the effect of labile proton concentration. The technique was validated by numerical simulations and studies on phantoms and ex vivo porcine spines. Four male (ages 42.8 ± 18.3) and two female patients (ages 55.5 ± 2.1) with LBP and scheduled for discography were examined with the method on a 3.0 Tesla MR scanner. RROC measurements were compared with discography outcomes using paired t-test.
Simulation and phantom results indicated RROC is a concentration independent and pH level-dependent technique. Porcine spine study results found higher RROC value was related to lower pH level. Painful discs based on discography had significant higher RROC values than those with negative diagnosis (P < 0.05).
RROC imaging is a promising pH level dependent MRI technique that has the potential to be a noninvasive imaging tool to detect painful IVDs in vivo.
低pH值与椎间盘（IVD）源性腰痛（LBP）相关。本研究的目的是开发一种体内pH值依赖性磁共振成像（MRI）方法，用于检测椎间盘源性LBP，且无需使用外源性造影剂。
使用R1ρ色散与化学交换饱和转移（CEST）的比值（RROC）对IVD进行pH值依赖性成像，同时消除不稳定质子浓度的影响。该技术通过数值模拟以及对体模和离体猪脊柱的研究进行了验证。对4名男性（年龄42.8±18.3岁）和2名女性患者（年龄55.5±2.1岁）进行了研究，这些患者患有LBP且计划进行椎间盘造影，在3.0特斯拉MR扫描仪上用该方法对他们进行了检查。使用配对t检验将RROC测量结果与椎间盘造影结果进行比较。
模拟和体模结果表明RROC是一种与浓度无关且依赖于pH值的技术。猪脊柱研究结果发现，较高的RROC值与较低的pH值水平相关。基于椎间盘造影的疼痛椎间盘的RROC值显著高于诊断为阴性的椎间盘（P<0.05）。
RROC成像技术是一种很有前景的pH值依赖性MRI技术，有潜力成为一种在体内检测疼痛性IVD的非侵入性成像工具。
