Visualising lymphatic flow dynamics during complex physical therapy: A photoacoustic imaging study

Area of Science:

• Biomedical imaging
• Vascular biology
• Lymphedema research

Background:

• Complex physical therapy (CPT), combining compression and exercise, is crucial for lymphedema management.
• Visualizing lymphatic vessels in vivo is challenging due to their small size and transparency.
• Current methods lack the detail for real-time lymphatic flow assessment during therapy.

Purpose of the Study:

• Introduce photoacoustic imaging (PAI) as a novel method for visualizing lymphatic flow dynamics.
• Evaluate the efficacy of PAI in assessing lymphatic function under CPT conditions.
• Explore the synergistic effects of compression and exercise on lymphatic flow.

Main Methods:

• Employed photoacoustic lymphangiography with indocyanine green in four healthy subjects.
• Simulated compression therapy (approx. 20 mmHg) using transparent film dressing.
• Applied exercise stress to mimic CPT conditions while monitoring lymphatic vessels via PAI.

Main Results:

• PAI provided detailed visualization of lymphatic and blood vessels.
• Compression caused superficial vein collapse while lymphatic vessels remained intact.
• Lymphatic pumping frequency was highest during combined compression and exercise, indicating synergy.

Conclusions:

• PAI is a promising tool for understanding CPT mechanisms in lymphedema.
• PAI allows simultaneous assessment of veins and lymphatic vessels, aiding vascular change evaluation.
• Further research is needed due to the study's small sample size and specific exercise regimen.