Ultra-wideband three-dimensional optoacoustic tomography

Abstract

Broadband optoacoustic waves generated by biological tissues excited with nanosecond laser pulses carry information corresponding to a wide range of geometrical scales. Typically, the frequency content present in the signals generated during optoacoustic imaging is much larger compared to the frequency band captured by common ultrasonic detectors, the latter typically acting as bandpass filters. To image optical absorption within structures ranging from entire organs to microvasculature in three dimensions, we implemented optoacoustic tomography with two ultrasound linear arrays featuring a center frequency of 6 and 24 MHz, respectively. In the present work, we show that complementary information on anatomical features could be retrieved and provide a better understanding on the localization of structures in the general anatomy by analyzing multi-bandwidth datasets acquired on a freshly excised kidney.

Unleashing Optics and Optoacoustics for Developmental Biology

“…Higher resolution might be achieved with optoacoustic tomography, as seen in Figure 1B-D where Razansky et al [34] show how MSOT can be used to resolve fluorophores in the brain of an adult transgenic zebrafish in vivo with a scalable spatial resolution of a few tenths of microns. In addition, Gateau et al have shown that 3D optoacoustic tomography enables imaging depths of several millimeters to centimeters with scalable resolution under $100 mm [35]. Even higher resolution can be obtained, as shown by Omar et al, by making use of an ultra-wideband single element transducer with a bandwidth of 20-180 MHz [36], demonstrating an axial resolution of $4 mm and a lateral resolution of $18 mm for imaging depths up to 5 mm, allowing imaging of vascular structures under the skin or in small-animal model systems.…”

Optical mesoscopy without the scatter: broadband multispectral optoacoustic mesoscopy

“…The experimental setup used in this study is based on a translate-rotate geometry previously described [11,12]. Figure 1(a) shows a schematic of the system.…”

“…Data sets were obtained by employing a rotation range of 178.5° and a fixed translation range for each of the transducer arrays employed (Table 1). This translation range ensured a good coverage of the sample in planes transversal to the detection probe (perpendicular to the z-axis) and enabled to obtain a homogeneous resolution over the covered scanning area [12,16]. The scanner allowed imaging biological samples contained in a cylinder of 10 mm diameter and 10 mm height.…”

“…), we have shown that optoacoustic mesoscopy implemented in tomographic mode can yield superior imaging performance, providing an isotropic in-plane resolution through volumetric specimen [10]. Tomographic Optoacoustic Mesoscopy (TOM) employs sampling of ultrasonic waves at multiple angles (projections) around the object imaged [11,12] and reconstructs the origin of the sound waves within the sample; the sound generated in response to the absorption of photon-intensity gradients (typically photon pulses) due to thermo-elastic expansion. The reconstruction of the sound origin yields images characteristic of optical absorption at the wavelength of emission.…”

All-optical highly sensitive akinetic sensor for ultrasound detection and photoacoustic imaging

“…While broad-band detection can be achieved with polyvinylidene-fluorid-based (PVDF) hydrophones, for the most sensitive PZT transducers, the BW is typically on the same order of magnitude as the center frequency, resulting in narrow bandwidths, especially if highly sensitive detection of frequencies below 10 MHz is required. In photoacoustic imaging, artifacts are created by the simultaneous detection of small and large structures, where both high-and low-frequency spectral components are integrated for image reconstruction [8,9]. Therefore, a sensor with a high sensitivity to low-and high-frequency spectral components would be best suited for PAI.…”