Non-invasive Quantitative Analysis of Specific Fat Accumulation in Subcutaneous Adipose Tissues using Raman Spectroscopy

Abstract

Subcutaneous adipose tissue (SAT), visceral adipose tissue (VAT), and fat beneath the dermis layer were investigated using a ball lens top hollow optical fiber Raman probe (BHRP). Hamsters were fed with trilinolein (TL) and tricaprin (TC) for six weeks and measurements were carried out every two weeks. The BHRP with an 800 μm diameter fused-silica ball lens was able to obtain information on the subcutaneous fat in a totally non-invasive manner. Changes in the concentration of TL and TC during the treatment were analyzed, and the relationship between fat accumulation and dietary fat was studied. It was found that SAT had, in general, a higher degree of unsaturation than VAT. The accumulation rate of TC found in SAT and VAT was 0.52 ± 0.38 and 0.58 ± 0.4%, respectively, while the TL accumulation rate was 4.45 ± 1.6 and 4.37 ± 2.4%, respectively. The results suggest different metabolic pathways for TC, a typical medium-chain fatty acid, and TL, a long-chain unsaturated fatty acid. Raman subsurface spectra were successfully obtained and used to analyze the subcutaneous fat layer. The accumulation rates of TL and TC found in skin fat were 5.01 ± 3.53% and 0.45 ± 0.36%, respectively. The results demonstrate the high feasibility of Raman spectroscopy for non-invasive analysis of adipose tissue.

Self-absorption corrected non-invasive transmission Raman spectroscopy (of biological tissue)

“…Most notable exhibited by the relative intensity variation between the two peaks highlighted with (*) as a function of sample thickness. These two bands are assigned to C-C bending modes of the lipid skeleton, 41,42 and relative changes would not be expected normally within a relatively homogeneous sample. This is evidenced clearly by plotting the peak intensity ratios as a function of sample thickness.…”

Raman spectroscopy and its use for live cell and tissue analysis

“…Meksiarun et al succeeded in collecting information on subsurface tissue using a painless method with the fiber optic Raman probe [14,15]. Fats are indispensable materials in the human body, but too much fat causes obesity which often correlates to other adult diseases.…”

Tracing molecular dephasing in biological tissue

“…As was discussed in the introduction, the latter condition represents the case of homogenously broadened line. Therefore, Some comparison can be made with spontaneous Raman data available for fats [14,15]. We did not find any data on the relevant case that is obtained with a coherent frequency-domain technique.…”