Quantitative chemical exchange saturation transfer MRI of intervertebral disc in a porcine model.
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 kswbetween 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 kswand 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 kswmeasured using qCEST MRI is highly correlated with pH level. In the animal studies, the relationship can be described as ksw=9.2 × 106× 10-pH+ 196.9, R2= 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.
Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA.|Department of Bioengineering, University of California Los Angeles, Los Angeles, California, USA.
Zhengwei
Z
Zhou
Skeletal Biotech Laboratory, The Hebrew University-Hadassah Faculty of Dental Medicine, Ein Kerem, Jerusalem, Israel.
Maxim
M
Bez
Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA.|Department of Surgery, Cedars-Sinai Medical Center, Los Angeles, California, USA.|Board of Governors Regenerative Medicine Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA.
Wafa
W
Tawackoli
Department of Imaging, Cedars-Sinai Medical Center, Los Angeles, California, USA.
Joseph
J
Giaconi
Department of Surgery, Cedars-Sinai Medical Center, Los Angeles, California, USA.|Board of Governors Regenerative Medicine Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA.
Dmitriy
D
Sheyn
Department of Surgery, Cedars-Sinai Medical Center, Los Angeles, California, USA.|Board of Governors Regenerative Medicine Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA.
Sandra
S
de Mel
Department of Imaging, Cedars-Sinai Medical Center, Los Angeles, California, USA.
Marcel M
MM
Maya
Department of Imaging, Cedars-Sinai Medical Center, Los Angeles, California, USA.
Barry D
BD
Pressman
Skeletal Biotech Laboratory, The Hebrew University-Hadassah Faculty of Dental Medicine, Ein Kerem, Jerusalem, Israel.|Department of Surgery, Cedars-Sinai Medical Center, Los Angeles, California, USA.|Board of Governors Regenerative Medicine Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA.
Zulma
Z
Gazit
Skeletal Biotech Laboratory, The Hebrew University-Hadassah Faculty of Dental Medicine, Ein Kerem, Jerusalem, Israel.|Department of Surgery, Cedars-Sinai Medical Center, Los Angeles, California, USA.|Board of Governors Regenerative Medicine Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA.
Gadi
G
Pelled
Skeletal Biotech Laboratory, The Hebrew University-Hadassah Faculty of Dental Medicine, Ein Kerem, Jerusalem, Israel.|Department of Surgery, Cedars-Sinai Medical Center, Los Angeles, California, USA.|Board of Governors Regenerative Medicine Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA.
Dan
D
Gazit
Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA.|Department of Bioengineering, University of California Los Angeles, Los Angeles, California, USA.|Department of Imaging, Cedars-Sinai Medical Center, Los Angeles, California, USA.
Debiao
D
Li
D000465:Algorithms; D000818:Animals; D015415:Biomarkers / Q000032:analysis; D006025:Glycosaminoglycans / Q000032:analysis*; D006863:Hydrogen-Ion Concentration; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D007403:Intervertebral Disc / Q000033:anatomy & histology / Q000737:chemistry*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods*; D008297:Male; D057054:Molecular Imaging / Q000379:methods*; D019047:Phantoms, Imaging; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013552:Swine; D013556:Swine, Miniature
D015415:Biomarkers; D006025:Glycosaminoglycans
CEST; gagCEST; intervertebral disc; low back pain; pH; quantitative CEST
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