Spatially offset Raman spectroscopy for photon migration studies in bones with different mineralization levels

Area of Science:

• Biomedical Optics
• Spectroscopy
• Materials Science

Background:

• Spatially Offset Raman Spectroscopy (SORS) offers non-invasive subsurface chemical analysis.
• Estimating SORS penetration depth in bone is challenging due to complex material properties.
• Understanding bone composition's effect on SORS is vital for in vivo diagnostics.

Purpose of the Study:

• Investigate how bone mineralization influences photon migration in SORS.
• Determine the maximum depth SORS can penetrate through different bone types.
• Inform the optimal SORS parameters for non-invasive bone condition diagnosis.

Main Methods:

• Utilized 830 nm laser excitation for SORS analysis.
• Examined deer antler, equine metacarpal, and whale tympanic bone samples.
• Constructed bone stacks with embedded polytetrafluoroethylene (PTFE) for signal recovery tests.

Main Results:

• Recovered Raman signals through 4.4-4.7 mm of cortical bone at SORS offsets of 8.0-9.5 mm.
• Demonstrated that bone mineralization and porosity impact SORS penetration depth.
• Successfully detected PTFE signals through mineralized bone samples.

Conclusions:

• Bone mineralization significantly affects SORS signal recovery depth.
• SORS shows potential for non-invasive diagnosis of bone diseases through skin.
• Data guides selection of optimal SORS offsets for detecting bone pathologies.