Switchable preamplifier for dual modal photoacoustic and ultrasound imaging

Photoacoustic (PA) imaging is a high-fidelity biomedical imaging
 technique based on the principle of molecular-specific optical
 absorption of biological tissue constitute. Because PA imaging shares
 the same basic principle as that of ultrasound (US) imaging, the use
 of PA/US dual-modal imaging can be achieved using a single system.
 However, because PA imaging is limited to a shallower depth than US
 imaging due to the optical extinction in biological tissue, the PA
 signal yields a lower signal-to-noise ratio (SNR) than US images. To
 selectively amplify the PA signal, we propose a switchable
 preamplifier for acoustic-resolution PA microscopy implemented on an
 application-specific integrated circuit. Using the preamplifier, we
 measured the increments in the SNR with both carbon lead and wire
 phantoms. Furthermore, in vivo whole-body PA/US
 imaging of a mouse with a preamplifier showed enhancement of SNR in
 deep tissues, unveiling deeply located organs and vascular networks.
 By selectively amplifying the PA signal range to a level similar to
 that of the US signal without contrast agent administration, our
 switchable amplifier strengthens the mutual complement between PA/US
 imaging. PA/US imaging is impending toward clinical translation, and
 we anticipate that this study will help mitigate the imbalance of
 image depth between the two imaging modalities.