Versatile vasculature chips for ultrasound localization microscopy.

Area of Science:

• Biomedical Engineering
• Medical Imaging
• Microfluidics

Background:

• Ultrasound localization microscopy (ULM) offers high-resolution microvasculature imaging beyond the diffraction limit using microbubbles.
• Evaluating ULM performance is difficult due to the absence of realistic, hierarchical microvascular phantoms.

Purpose of the Study:

• To develop a versatile and customizable fabrication protocol for creating microvascular network phantoms with ground truth.
• To establish a platform for evaluating and optimizing ultrasound-based microvascular imaging techniques.

Main Methods:

• An organ-on-a-chip protocol using agarose-based micro-vessel networks was adapted from microfluidic chip techniques.
• Two phantom patterns were created: a leaf-inspired venation network and a human kidney vasculature projection.
• Microbubble solutions were introduced into the phantoms via capillary force and gravity.

Main Results:

• ULM-reconstructed vasculature maps showed good agreement with the ground truth.
• High sensitivity (0.97 and 0.95) but lower precision (0.37 and 0.60) was observed for the leaf and kidney phantoms, respectively.
• ULM demonstrated vessel reconstruction capability but also produced false positive predictions.

Conclusions:

• The developed protocol provides a flexible platform for generating realistic microvascular phantoms.
• This facilitates the advancement and validation of ultrasound microvascular imaging technologies.
• The phantoms enable rigorous performance evaluation of ULM in preclinical and clinical settings.