Improved imaging interfaces on a co-registered ultrasound and optical microscopy multiscale system

Area of Science:

• Biomedical Optics
• Acoustic Imaging
• Multimodal Microscopy

Background:

• Integrating ultrasound (US) with multiphoton microscopy (MPM) offers comprehensive tissue characterization by combining contrast mechanisms across spatial scales.
• Existing implementations suffer from degraded US image quality near the glass optical window due to off-axis acoustic noise (clutter).

Purpose of the Study:

• To reduce acoustic clutter near the optical window in US-MPM systems.
• To achieve this without compromising MPM image quality.
• To evaluate different optical window materials and ultrasound beamforming techniques.

Main Methods:

• Assessed clutter in B-mode US images using glass and polymer films (PMP, COC, PC, etc.).
• Employed physically or synthetically focused US beamforming with varied focal configurations (f/#).
• Evaluated MPM image quality using second harmonic generation (SHG) point spread function (PSF) measurements.
• Quantified collagen fiber alignment in rat tail tendon and collagen gels using SHG.

Main Results:

• Cyclic olefin copolymer (COC) and Ibidi® polymer coverslips reduced acoustic clutter by over 40% compared to glass at receive f/# ≥ 2.
• These materials showed minimal impact on SHG PSF and collagen alignment errors (<5% relative to glass).
• Ultrasound speckle clarity improved near the optical window with COC and high f/#.

Conclusions:

• COC or Ibidi® optical windows significantly enhance US image quality in multimodal systems.
• These materials do not compromise MPM image quality.
• The findings support future multimodal studies requiring high-quality, co-registered US and MPM data.