Characterization of optical clearing mechanisms in muscle during treatment with glycerol and gadobutrol solutions

Abstract

The recent increasing interest in the application of radiology contrasting agents to create transparency in biological tissues implies that the diffusion properties of those agents need evaluation. The comparison of those properties with the ones obtained for other optical clearing agents allows to perform an optimized agent selection to create optimized transparency in clinical applications. In this study, the evaluation and comparison of the diffusion properties of gadobutrol and glycerol in skeletal muscle was made, showing that although gadobutrol has a higher molar mass than glycerol, its low viscosity allows for a faster diffusion in the muscle. The characterization of the tissue dehydration and refractive index matching mechanisms of optical clearing was made in skeletal muscle, namely by the estimation of the diffusion coefficients for water, glycerol and gadobutrol. The estimated tortuosity values of glycerol (2.2) and of gadobutrol (1.7) showed a longer path‐length for glycerol in the muscle.

Clinical MRI contrast agent improves fluorescent imaging of red fluorescent protein expression in-vivo due to the effect of tissue optical clearing

“…The measurement of the refractive index of the Gadavist TM (1.0 mmol/ml) was 1.4260 at a wavelength of 589.6 nm. 11 Effective OC and the validity of the concept of refractive index matching of tissue optical inhomogeneities causing strong light scattering was shown for the action of an 80% aqueous solution of Gadavist TM , having a refractive index of 1.4074, on muscle tissue. 11 This refractive index is much higher than of interstitial fluid (1.35), thus solution is effective for OC.…”

“…11 Effective OC and the validity of the concept of refractive index matching of tissue optical inhomogeneities causing strong light scattering was shown for the action of an 80% aqueous solution of Gadavist TM , having a refractive index of 1.4074, on muscle tissue. 11 This refractive index is much higher than of interstitial fluid (1.35), thus solution is effective for OC. The measurement of the refractive index of Gadavist TM (1.0 mmol/ml) was 1.4260 at a wavelength of 589.6 nm.…”

“…This indicates the improvement of refractive index matching between the skin and various layers of subcutaneous tissue over time. 11 The presence of DMSO in the 0.7 M GB OC composition is the main cause of this sustained effect. The direct comparison of two OC regimens indicates that the differences in composition of 1M GB and 0.7 M GB-containing OC mixture are responsible for prolonged modification of tissue scattering environment, potentially due to the penetration of the OC composition into the deeper layers of tissue enabled by DMSO.…”

“…The measurement of the refractive index of Gadavist TM (1.0 mmol/ml) was 1.4260 at a wavelength of 589.6 nm. 11 The effectiveness of OС and the validity of the concept of matching the refractive index of optical inhomogeneities of the tissue, initially causing strong light scattering, is shown when the muscle tissue is exposed to an 80% aqueous solution of Gadavist TM , which has a refractive index of 1.4074. 11 This refractive index is much higher than that of the interstitial fluid (1.35), so the solution is effective in OC.…”