Origin and quantification of differences between normal and tumor tissues observed by terahertz spectroscopy

Area of Science:

• Biomedical Optics
• Medical Physics
• Cancer Research

Background:

• Differences in refractive index between normal and tumor tissues are observed using terahertz spectroscopy.
• Understanding these differences is crucial for developing non-invasive diagnostic tools.

Purpose of the Study:

• To quantitatively describe the origin of refractive index differences between normal and tumor tissues.
• To estimate the contribution of water content and cell density to these differences.

Main Methods:

• Terahertz time domain spectroscopy (THz-TDS) was used to measure the refractive index of fresh and paraffin-embedded rat tissue samples.
• Hematoxylin and eosin staining was employed to quantify cell nuclei density.

Main Results:

• Tumor tissues exhibited approximately 5% higher water content compared to normal tissues.
• Tumor tissues showed a greater than 15% increase in cell nuclei percentage per unit area.
• Both increased water content and cell density contributed to a higher refractive index (approx. 0.05) in tumor tissues.

Conclusions:

• The higher refractive index in tumor tissues is attributed to both increased water content and cell density.
• Terahertz spectroscopy holds potential for detecting brain tumors in human tissues based on these optical property differences.