“…Recently, the combination of a sensitivity theorem [8,12,13] and the acousto-electric (AE) effect [14][15][16] first described in [17] has been used to map internal currents [18,19] and dipoles [20]. That is, the relation between the AE voltage signal detected using paired electrodes and the ultrasound (US) pulsed echo signal is used (for instance, the amplitude of the AE signal is proportional to that of the US signal [15], in which the proportional coefficient is about 0.1% MPa À1 in a 0.9% NaCl solution used [16]) for monitoring cardiac [18,20] and nerve [19] activity.…”