Reliable chemical exchange saturation transfer imaging of human lumbar intervertebral discs using reduced‐field‐of‐view turbo spin echo at 3.0 T

Abstract

The reduced field-of-view (rFOV) turbo-spin-echo (TSE) technique, which effectively suppresses bowel movement artifacts, is developed for the purpose of chemical exchange saturation transfer (CEST) imaging of the intervertebral disc (IVD) in vivo. Attempts to quantify IVD CEST signals in a clinical setting require high reliability and accuracy, which is often compromised in the conventionally used technique. The proposed rFOV TSE CEST method demonstrated significantly superior reproducibility when compared with the conventional technique on healthy volunteers, implying it is a more reliable measurement. Phantom study revealed a linear relation between CEST signal and glycosaminoglycan (GAG) concentration. The feasibility of detecting IVD degeneration was demonstrated on a healthy volunteer, indicating that the proposed method is a promising tool to quantify disc degeneration.

Age‐dependency of glycosaminoglycan content in lumbar discs: A 3t gagcEST study

“…Taken together, the observed loss of gagCEST effect with age may be explained by a loss of glycosaminoglycans due to physiological IVD degeneration and proteolysis in the aging discs. This finding is consistent with data acquired by Haneder et al and Liu et al, which show a decrease of gagCEST effect with anatomical disc degeneration. Our study is limited by a lack of knowledge of the true glycosaminoglycan content, which might be assessed by histological samples only.…”

“…In our study, we used the same B 1 amplitude averaged over time as reported by Haneder et al However, different field strengths have been used previously for gagCEST imaging (Liu et al: 0.8 μT, Saar et al: 1.8 μT, Kim et al: 1.5 μT in phantoms and 0.75 μT in IVDs) . The B 1 amplitude could have an influence on both, the gagCEST asymmetry as well as the spillover effect.…”

Detection of extracellular matrix degradation in intervertebral disc degeneration by diffusion magnetic resonance spectroscopy

“…Compared with T2 mapping, T1ρ imaging possesses a better dynamic range and, hence, a better sensitivity to tissue hydration and PG content change during IVDD . Chemical exchange saturation transfer (CEST) imaging can detect GAG loss, and several studies have demonstrated the feasibility of CEST imaging of GAG content and pH changes during IVDD . The use of 23 Na MRI has also been explored for measuring the sodium concentration in intervertebral disc as an index for fixed charge density and GAG content in the ECM .…”

Detection of low back pain using pH level-dependent imaging of the intervertebral disc using the ratio of R1ρdispersion and −OH chemical exchange saturation transfer (RROC)

“…A two‐dimension (2D) reduced field‐of‐view (rFOV) TSE CEST sequence was previously introduced . rFOV can effectively suppress motion artifacts caused by bowel movement, and improve measurement reproducibility.…”

“…Post processing was performed with custom‐written programs in Matlab (The Mathworks, Natick, MA). CEST images were processed as previously described . Spin‐lock images at different SLTs were fitted into a mono‐exponential decay model to obtain R 1ρ values using least‐squares fitting, pixel by pixel.…”