Assessment of glycosaminoglycan content in intervertebral discs using chemical exchange saturation transfer at 3.0 Tesla: preliminary results in patients with low-back pain.
OBJECTIVE
To evaluate glycosaminoglycan-dependent chemical exchange saturation transfer (gagCEST) imaging at 3-T magnetic resonance imaging (MRI) for quantification of glycosaminoglycan (GAG) content in intervertebral discs (IVDs) in patients with low-back pain (LBP).


METHODS
Sixteen patients with LBP were examined in this Institutional Review Board-approved study using a clinical whole-body system. The MRI protocol included standard morphological imaging, sagittal T2-mapping and gagCEST imaging. IVD grading according to the Pfirrmann score and region-of-interest analysis of the annulus fibrosus (AF) and the nucleus pulposus (NP) in gagCEST and T2 maps were performed before data were statistically tested for correlations between imaging techniques and quantitative differences between different grades of IVD degeneration.


RESULTS
GagCEST values of the NP were significantly (P < 0.001) lower in degenerative IVDs (Pfirrmann 3 + 4) compared with non-degenerative IVDs (Pfirrmann 1 + 2), but only a weak linear correlation (r = 0.299) with the T2 relaxation times was found. GagCEST values of the NP exhibited a moderate negative correlation with Pfirrmann grades (r = -0.449).


CONCLUSIONS
The known loss of GAG in the NP with increasing grade of morphological degeneration can be assessed using gagCEST imaging at 3.0 T. The correlation with single Pfirrmann grades and T2 relaxation times only seems to be moderate, indicating a substantial difference in information provided by the techniques.
Department of Radiology, Centre for High-Field MR, Medical University of Vienna, Lazarettgasse 14, 1090 Vienna, Austria.
Stefan
S
Haneder
Sebastian R
SR
Apprich
Benjamin
B
Schmitt
Henrik J
HJ
Michaely
Stefan O
SO
Schoenberg
Klaus M
KM
Friedrich
Siegfried
S
Trattnig
D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000032:analysis; D005260:Female; D006025:Glycosaminoglycans / Q000032:analysis*; D006801:Humans; D007403:Intervertebral Disc / Q000737:chemistry* / Q000473:pathology; D055959:Intervertebral Disc Degeneration / Q000150:complications / Q000175:diagnosis / Q000378:metabolism*; D017116:Low Back Pain / Q000175:diagnosis* / Q000209:etiology / Q000378:metabolism*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D057054:Molecular Imaging / Q000379:methods*; D010865:Pilot Projects; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
D015415:Biomarkers; D006025:Glycosaminoglycans