Quantum cascade laser-based hyperspectral imaging of biological tissue

Area of Science:

• Biomedical Optics
• Spectroscopy
• Histopathology

Background:

• Vibrational spectroscopy enables label-free histopathology by analyzing molecular vibrations in tissue.
• Current biomedical vibrational imaging is limited by long acquisition times and high equipment costs, hindering clinical adoption.
• Existing methods like Fourier transform infrared (FTIR) imaging are time-consuming for large-area, high-resolution hyperspectral data.

Purpose of the Study:

• To develop a rapid and cost-effective hyperspectral imaging method for unstained tissue sections.
• To overcome the limitations of slow acquisition speeds in current vibrational microscopy techniques.
• To demonstrate the potential of this new approach for routine histopathological analysis.

Main Methods:

• Utilized a fast-tuning quantum cascade laser (QCL) coupled with a microbolometer array detector.
• Acquired hyperspectral images of an unstained mouse jejunum thin section (3.1 x 2.8 mm²) in the 9.2–9.7 μm range.
• Achieved spectral resolution of approximately 1 cm⁻¹ with diffraction-limited spatial resolution within 5 minutes.

Main Results:

• Demonstrated rapid hyperspectral image acquisition of unstained tissue in under 5 minutes.
• Achieved significant reductions in acquisition time compared to standard FTIR imaging (over 1 order of magnitude per wavenumber interval and 3 orders of magnitude per image area).
• Showcased the potential for substantial cost reduction in biomedical vibrational imaging equipment.

Conclusions:

• The combination of a fast-tuning QCL and microbolometer array detector enables rapid hyperspectral imaging of tissues.
• This technique significantly accelerates image acquisition, paving the way for routine label-free histopathology.
• The approach holds promise for reducing the cost and increasing the accessibility of advanced molecular imaging in diagnostics.