Comparison of glycosaminoglycan chemical exchange saturation transfer using Gaussian-shaped and off-resonant spin-lock radiofrequency pulses in intervertebral disks.

PURPOSE

To investigate, if a train of spin-lock pulses (chemical exchange saturation transfer with spin-lock pulses = CESL) improves biochemical glycosaminoglycan imaging compared with conventional chemical exchange saturation transfer with Gaussian-shaped pulses (CEST) in lumbar intervertebral discs.

METHODS

T , CEST, and CESL imaging was performed in lumbar intervertebral discs of 15 healthy volunteers at 3 Tesla. Mean and standard deviation of the asymmetric magnetization transfer ratio (MTR ), the asymmetric spin-lock ratio (SLR ) and T values were calculated for nucleus pulposus (NP) and annulus fibrosus (AF). Wilcoxon test was used to analyze differences between MTR and SLR . Pearson correlation was used to determine the relationship between MTR , SLR and T .

RESULTS

Data showed no significant difference between MTR and SLR (NP: P = 0.35; AF: P = 0.34). MTR and SLR values differed significantly between NP and AF (MTR : P = 0.014, SLR : P = 0.005). T values correlated significantly with MTR (NP: ρ = 0.76, P < 0.001; AF: ρ = 0.60, P < 0.001) and SLR (NP: ρ = 0.73, P < 0.001; AF: ρ = 0.47, P < 0.001).

CONCLUSION

CESL does not improve the chemical exchange asymmetry effect compared with conventional CEST, but leads to comparable results. Magn Reson Med 78:280-284, 2017. © 2016 International Society for Magnetic Resonance in Medicine.