Multiple bandwidth volumetric optoacoustic tomography using conventional ultrasound linear arrays

In optoacoustic imaging absorbing structures excited with short laser pulses generate broadband ultrasound waves, which tomographically detected outside the sample enable reconstruction of initial pressure distribution. As light scatters in biological tissues, the excitation has a three-dimensional (3D) pattern allocation. Accurate reconstruction of the 3D distribution of optical absorption requires a large solid angle of detection of the ultrasonic field. Moreover, the center frequency and bandwidth of a given detector define the range of structure sizes it is able to resolve. Therefore, detectors with different frequency bandwidths record different subsets of information. A volumetric optoacoustic system using linear ultrasound arrays with different central frequencies, 6MHz and 24MHz, is introduced. By employing a novel scanning geometry that takes advantage of the high sensitivity on the transversal dimension of these linear probes, high resolution optoacoustic signals are being recorded. Resolution performance and biological capabilities are demonstrated with a 20um crossed-suture phantom and an excised mouse liver lobe.