Absolute Quantification of Tissue Composition by Raman Spectroscopy

Phantom-calibrated Raman spectroscopy (PC-Raman) quantifies cartilage biochemical constituents as tissue wet-weight percentages, matching independent biochemical assays with R-squared 0.88–0.92 and slopes ~1.0.

• Why it matters: Absolute Raman quantification is limited by tissue-dependent optical properties, variable sampling volume, and the absence of normalization standards for scaling spectra to biochemical composition.
• What they did: PC-Raman trains nonlinear polynomial models on chemically defined phantoms that mimic essential constituent variability, then validates using biochemically perturbed live cartilage explants against independent biochemical assays.
• The result: PC-Raman resolves constituent-specific changes in cartilage with quantitative agreement (R-squared 0.88–0.92; 95% confidence intervals ±2.7–3.2%pt), enabling non-destructive longitudinal monitoring from imaging to in-vivo equine cartilage repair.