Reflection-mode virtual histology using photoacoustic remote sensing microscopy

Area of Science:

• Biomedical Imaging
• Histopathology
• Optical Physics

Background:

• Current histological methods require extensive tissue preparation, causing significant clinical feedback delays (2-3 weeks).
• Bright-field microscopy is standard but labor-intensive and time-consuming.
• Need for rapid, non-invasive imaging techniques in pathology.

Purpose of the Study:

• To comprehensively study the application of photoacoustic remote sensing (PARS) for label-free tissue visualization.
• To assess PARS's capability for rapid assessment of large tissue samples and high-contrast imaging.
• To demonstrate PARS's utility in various histopathological and fresh tissue preparations.

Main Methods:

• Utilized photoacoustic remote sensing (PARS), a reflection-mode imaging modality.
• Employed non-contact visualization of intrinsic endogenous optical absorption contrast.
• Applied PARS to formalin-fixed paraffin-embedded tissues, unstained slides, frozen sections, and fresh tissues.

Main Results:

• PARS visualized salient subcellular structures in diverse human and murine tissues.
• The technique provided rapid assessment (<10 min for >1 cm² samples).
• PARS simulated conventional stains (H&E) and identified pathologies like basal cell carcinoma.

Conclusions:

• PARS is a versatile, label-free imaging modality for histopathology.
• It overcomes limitations of traditional tissue preparation, enabling real-time assessment.
• PARS represents a significant advancement towards a real-time clinical microscope.