Advancements in 2D blood vessel angiography using magneto-thermo-acoustic imaging

Based on the thermoacoustic (TA) effect of magnetic nanoparticles (MNPs), we propose a novel TA imaging method for 2D vascular distribution mapping under a single-pulse magnetic field. By numerically simulating the forward problem, we model the propagation process of the TA signal, incorporating gradient-concentration MNPs to demonstrate the functional imaging capabilities of MTA. We constructed a 2D vessel model based on real vessels for the inverse problem. By comparing the filtered inverse projection algorithm with the time-reversal method, we verified the feasibility of reconstructing the vessel model image using magnetic-thermo-imaging. One major innovation of this work is the development and use of a 16-channel array ultrasound (US) transducer (16-CAUT) with a center frequency of 2.25 MHz. This device represents a significant advancement, achieving a spatial resolution of 0.35 mm in vascular phantoms for the first time. Additionally, we investigated the effect of different US transducer sampling numbers on image quality. We evaluated the image metrics using root mean square error, peak signal-to-noise ratio, and structural similarity. contrast-to-noise ratio and full width at half maximum were also evaluated for different filtering levels. Our results demonstrated the effectiveness of bilateral filtering, a post-filtering method suited for time-reversal image reconstruction. This method is particularly effective at preserving edges while removing background noise, due to its capability to handle the boundary inversion of the acoustic source. Experimentally, our magneto-thermo-acoustic imaging platform achieved high contrast and a spatial resolution greater than 0.35 mm, demonstrating the potential to assist in image monitoring for vascular thrombolysis therapy.