Detection of low back pain using pH level-dependent imaging of the intervertebral disc using the ratio of R1ρ dispersion and -OH chemical exchange saturation transfer (RROC).
OBJECTIVE
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.


METHODS
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.


RESULTS
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).


CONCLUSIONS
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.
Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA; Department of Biomedical Engineering, Northwestern University, Chicago, Illinois, USA.
Qi
Q
Liu
Wafa
W
Tawackoli
Gadi
G
Pelled
Zhaoyang
Z
Fan
Ning
N
Jin
Yutaka
Y
Natsuaki
Xiaoming
X
Bi
Avrom
A
Gart
Hyun
H
Bae
Dan
D
Gazit
Debiao
D
Li
D000465:Algorithms; D000818:Animals; D015415:Biomarkers / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D006878:Hydroxides; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D007403:Intervertebral Disc / Q000737:chemistry*; D055959:Intervertebral Disc Degeneration / Q000150:complications / Q000175:diagnosis*; D017116:Low Back Pain / Q000175:diagnosis* / Q000209:etiology; D008279:Magnetic Resonance Imaging / Q000379:methods*; D019047:Phantoms, Imaging; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013552:Swine
D015415:Biomarkers; D006878:Hydroxides; C031356:hydroxide ion
CEST; Intervertebral disc; R1ρ dispersion; RROC; pH imaging