Work

Cross amplitude modulation imaging: theory and basic principles

Year: 2025

Type: article

Abstract: The introduction of genetically encoded gas vesicles (GVs), protein nanostructures with the ability to scatter sound, has created the possibility for deep tissue cellular imaging. GVs establish a platform for biomolecular engineering and were successfully repurposed into acoustic reporter genes and acoustic biosensors. Alongside molecular engineering developments, a method called cross amplitude modulation (xAM) has emerged as the gold standard for nondestructive ultrasound imaging of GVs, thanks to its sensitivity and specificity in living biological tissues. Here, we present latest xAM theory and imaging principles. Specifically, we report 1) analytical expressions for the X-wave beamwidth and primary-tosecondary lobes distance; 2) experimental observations of nondiffractive xAM beams; 3) a method to modulate the secondary lobe level of xAM beams; 4) a demonstration of the incoherent nature of the xAM image noise that can be leverage to increase sensitivity through frame averaging; and 5) a beamforming formalism to enhance xAM contrast-to-noise ratio without reducing framerate. Ultimately, the rise of the field of biomolecular ultrasound will rest on the co-development of genetically encoded probes and dedicated imaging methods such as xAM and its 3-D extension, nonlinear sound-sheet microscopy (NSSM).

Source: IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control

DOI: 10.1109/tuffc.2025.3614145

Authors: Hugues Favre, David Maresca

Institution: Delft University of Technology

Language: English

Topic: Photoacoustic and Ultrasonic Imaging

Subfield: Biomedical Engineering

Field: Engineering

Domain: Physical Sciences

Open Access status: hybrid

Estimated APC paid: $2,645

Funders: Chan Zuckerberg Initiative, H2020 Marie Skłodowska-Curie Actions