Acoustoelectric cardiac imaging (ACI) is a hybrid modality that exploits the interaction of an ultrasonic pressure wave and the resistivity of tissue to map current densities in the heart. This study demonstrates for the first time in vivo ACI in a swine model. ACI measured beat-to-beat variability (n = 20) of the peak of the cardiac activation wave at one location of the left ventricle as 5.32 ± 0.74 ~V, 3.26 ± 0.54 mm below the epicardial surface, and 2.67 ± 0.56 ms before the peak of the local electrogram. Cross-sectional ACI images exhibited propagation velocities of 0.192 ± 0.061 m/s along the epicardial-endocardial axis with an SNR of 24.9 dB. This study demonstrates beat-to-beat and multidimensional ACI, which might reveal important information to help guide electroanatomic mapping procedures during ablation therapy.

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Acoustoelectric Imaging (AEI) is a disruptive technology that exploits an ultrasound (US) beam to transiently interact with physiologic or artificial currents, producing a radiofrequency signature detected by one or more surface electrodes. By rapidly sweeping the US beam and simultaneously detecting the acoustoelectric modulations, 4D current density images are generated at high spatial resolution determined by the ultrasound beam focus. The principle has been used for in vivo mapping of currents in the swine heart during the cardiac activation wave. When applied to the brain, transcranial acoustoelectric imaging (tABI) overcomes limitations with electroencephalography (EEG), which suffers from poor spatial resolution and inaccuracies due to blurring of electrical signals as they pass through the brain and skull, and, unlike fMRI and PET that measure slow metabolic or hemodynamic signals, tABI directly maps fast time-varying current within a defined brain volume at the mm and ms scales. This invited presentation will describe the underlying physics and mathematics of tABI, recent progress and challenges using numerical simulations and bench-top models, and its potential impact as a cutting-edge noninvasive modality for fast and accurate electrical brain mapping in humans.

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