The research leading to these results has received funding from the European Research Council under grant agreement ERC-2010-StG-260991.

The detailed procedure for operating with the volumetric hand-held optoacoustic probe is described below. This procedure is performed according to approved institutional regulations regarding animal and human experiments.
1. System Preparation
<ol>
	<li>Switch on the laser for a warm-up period of ~15&#160;min prior to operation for stabilizing the output light beam.</li>
	<li>Place the water enclosing part with the isolating membrane that is in contact with the skin (Figure 1</strong...

<ol>
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B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=4-D+Photoacoustic+Tomography.">4-D Photoacoustic Tomography.</a> Sci Rep-Uk. 3, 10-1038 (2013).</li><li>Buehler, A., Dean-Ben, X. L., Claussen, J., Ntziachristos, V., Razansky, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Three-dimensional+optoacoustic+tomography+at+video+rate.">Three-dimensional optoacoustic tomography at video rate.</a> Optics express. 20 (20), 22712-22719 (2012).</li><li>Dean-Ben, X. 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The unique advantages offered by optoacoustic imaging techniques in small animal research have created strong motivation for translating the technology into clinical practice, with a number of diagnostics and treatment monitoring applications envisioned e.g., in breast and skin cancer, inflammation or peripheral vasculature diseases. However, as opposed to mice or smaller animals, which can be surrounded by a sufficient number of illumination sources and detection elements to create an effective tomographic imag...

Optoacoustic (photoacoustic) imaging attracts growing interest from the biological and medical research communities, as manifested by the ever increasing number of publications encompassing variety of new applications that exploit the unique advantages offered by the technology 1-5. In particular, the capacity to image spectrally distinctive photo-absorbing agents with high spatio-temporal resolution at depths far beyond the diffusive limit of light opens unprecedented capabilities for functional and molecular imaging 6-10.
Indeed, translation of the optoacoustic technology into clinical practice comes with promising prospects in diagnostics and treatment monitoring of many diseases. Yet, the limited propagation of photons in optically scattering and absorbing tissues and the generally weak responses associated with the optoacoustic phenomenon limit the applicable depth of the method. As a result, hand-held optoacoustic probes have been attempted to image parts accessible from outside of the body 11,12 while endoscopic systems are used to provide images from within the body by inserting them via natural orifices 13. Some low absorbing parts of human body, such as female breast, are also accessible by tomographic optoacoustic scanners 14,15. Of particular interest is the hand-held approach as it enables large versatility, similarly to ultrasonography. Here, adaptation of the common ultrasound linear array probes for optoacoustic imaging remains challenging, mainly due to fundamental differences in tomographic imaging requirements between ultrasound and optoacoustics. While high frame rates in standard ultrasonography are enabled by sequential transmit-receive schemes employing high pulse repetition frequencies in the kHz range, real-time three-dimensional optoacoustic imaging is achieved by simultaneous collection of volumetric tomographic data from a single interrogating laser pulse. Thus, high quality optoacoustic imaging implies acquisition of three-dimensional data from the largest possible solid angle around the imaged object.
Recently, we introduced the first handheld optoacoustic probe for three-dimensional (volumetric) imaging in real time16. The system is based on a two-dimensional array of 256 piezoelectric elements arranged upon a spherical surface (blue dots in Figure&#160;1A) covering an angle of 90&#176;. The size of the individual elements of approximately 3 x 3&#160;mm2, as well as their orientation and frequency bandwidth (approximately 2-6&#160;MHz) guarantee effective signal collection from a centimeter-scale volume surrounding the center of the sphere (black cube in Figure&#160;1A). Optical excitation of the imaging region is provided with a fiber bundle inserted through a central cylindrical cavity of the array, so that any wavelength susceptible of being transmitted through the fiber bundle can be used for imaging. An actual picture of the array of transducers along with the optical fiber bundle is shown in Figure&#160;1B. The efficient excitation and simultaneous detection of signals allows deep-tissue imaging with single-shot excitation (one laser pulse), so that real-time imaging at a frame rate determined by the pulse repetition frequency of the laser is further enabled with a graphics-processing-unit (GPU) implementation of the reconstruction procedure 17. A cylindrical casing with a transparent polyethylene membrane (Figure&#160;1C) is attached to the transducer array to enclose an acoustically transmitting liquid medium (water). The membrane is further coupled to the tissue by means of acoustic gel. A picture of the optoacoustic probe as being used in hand-held operation mode is shown in Figure&#160;1D.
The demonstrated three dimensional hand-held optoacoustic imaging combined with the real time functional imaging capacity come with important advantages for clinical diagnostics and a number of potential applications are envisioned for various indications, such as peripheral vascular disease, lymphatic system disorders, breast cancer, skin lesions, inflammation or arthritis 18. Furthermore, the fast imaging capacity enables visualization of dynamic biological events with the probe arranged in a stationary position. Combined with fast wavelength-tuning optical parametric oscillator (OPO) laser technology, this approach allows for real-time imaging of biodistribution of photo-absorbing agents. Thereby, new possibilities may equally emerge in small animal imaging applications, e.g., in studying tissue hemodynamics, in vivo cell tracking, visualization of pharmacokinetics, organ perfusion, targeted molecular imaging of tumors and cardiovascular system, or neuroimaging.
In this work we provide a detailed description of the experimental imaging protocol to operate with the spherical array optoacoustic hand-held probe and showcase performance in several typical clinical and small animal imaging scenarios.

<table border="0" cellpadding="0" cellspacing="0" width="1663">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:327px;">Name of Material/ Equipment</td>
			<td style="width:389px;">Company</td>
			<td style="width:171px;">Catalog Number</td>
			<td style="width:777px;">Comments/Description</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:327px;">Optical parametric oscillator (OPO)-based laser</td>
			<td style="width:389px;">Innolas Laser GmbH, Krailling (Germany)</td>
			<td style="width:171px;">custom-made</td>
			<td style="width:777px;">The laser provides laser pulses with a duration around 10ns and an energy up to 80mJ. 
			The wavelength is tunable between 680-950nm.</td>
		</tr>
		<tr height="45">
			<td height="45" style="height:45px;width:327px;">Spherical array of piezocomposite detectors</td>
			<td style="width:389px;">Imasonic SaS, Voray (France)</td>
			<td style="width:171px;">custom-made</td>
			<td style="width:777px;">The array consists of 256 piezoelectric sensors distributed on a spherical surface. 
			Each element has dimensions 3x3mm2, a central frequency of 4MHz and a bandwidth of 100%.&#160;</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:327px;">Data acquisition system (DAQ)</td>
			<td style="width:389px;">Falkenstein Mikrosysteme GmbH, Taufkirchen (Germany)</td>
			<td style="width:171px;">custom-made</td>
			<td style="width:777px;">The DAQ simultaneously acquires 256 signals at 40 megasamples per second and 2030 samples. 
			The input impedance is 1MW.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:327px;">Fiber bundle</td>
			<td style="width:389px;">CeramOptec GmbH, Bonn (Germany)</td>
			<td style="width:171px;">custom-made</td>
			<td style="width:777px;">The bundle consists of 480 individual fibers randomly distributed in the input and output. 
			The numerical aperture of each individual fiber is 0.22.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:327px;">Athymic Nude mouse</td>
			<td style="width:389px;">Harlan Laboratories (The Netherlands)</td>
			<td style="width:171px;">Athymic nude - Foxn1nu</td>
			<td style="width:777px;">The mouse was 8 weeks old (adult) at the time of the experiment. 
			The ethical protocol was approved by the Bavarian goverment (number 55.2.1.54-2632-102-11)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:327px;">Bepanthen cream</td>
			<td style="width:389px;">Bayer AG (Germany)</td>
			<td style="width:171px;">N/A</td>
			<td>Vet ointment to protect the eyes during anesthesia</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:327px;">Data processing software</td>
			<td style="width:389px;">Matlab (Mathworks, Natick, MA, USA)</td>
			<td style="width:171px;">custom-made</td>
			<td style="width:777px;">The data processing software was devoped at our institute. 
			It allows reconstruction at each wavelength and multi-wavelength unmixing, as well as further data processing.</td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;width:327px;">Water-enclosing part</td>
			<td style="width:389px;">N/A</td>
			<td style="width:171px;">custom-made</td>
			<td>This part contains the water that acts as an acoustic coupling medium between skin and transducer elements</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:327px;">Indocyanine green (ICG)</td>
			<td style="width:389px;">PULSION Medical Systems SE</td>
			<td style="width:171px;">N/A</td>
			<td style="width:777px;">ICG-PULSION (active ingredient: indocyanine green dye) is a drug used in cardiac, circulatory and micro-circulatory diagnostics, liver function diagnostics and ophthalmic angiography diagnostics.</td>
		</tr>
	</tbody>
</table>

universal hand-held three-dimensional optoacoustic imaging probe for deep tissue human angiography and functional preclinical studies in real time

The exclusive combination of high optical contrast and excellent spatial resolution makes optoacoustics (photoacoustics) ideal for simultaneously attaining anatomical, functional and molecular contrast in deep optically opaque tissues. While enormous potential has been recently demonstrated in the application of optoacoustics for small animal research, vast efforts have also been undertaken in translating this imaging technology into clinical practice. We present here a newly developed optoacoustic tomography approach capable of delivering high resolution and spectrally enriched volumetric images of tissue morphology and function in real time. A detailed description of the experimental protocol for operating with the imaging system in both hand-held and stationary modes is provided and showcased for different potential scenarios involving functional and molecular studies in murine models and humans. The possibility for real time visualization in three dimensions along with the versatile handheld design of the imaging probe make the newly developed approach unique among the pantheon of imaging modalities used in today&#8217;s preclinical research and clinical practice.

Representative results, demonstrating the capabilities of the described volumetric hand-held optoacoustic probe, are showcased in this section. In all cases, the light fluence on the skin surface was kept below the safety exposure limit of 20&#160;mJ/cm2 19.
The performance of the probe in real-time tracking peripheral human vasculature is showcased in Figure&#160;2. During the course of this experiment, the probe was slowly scanned along the hand of a he...

Watch this Scientific Journal Video about Universal Hand-held Three-dimensional Optoacoustic Imaging Probe for Deep Tissue Human Angiography and Functional Preclinical Studies in Real Time at JoVE.com

Universal Hand-held Three-dimensional Optoacoustic Imaging Probe for Deep Tissue Human Angiography and Functional Preclinical Studies in Real Time

We provide herein a detailed description of the experimental protocol for imaging with a newly developed hand-held optoacoustic (photoacoustic) system for three-dimensional functional and molecular imaging in real time. The demonstrated powerful performance and versatility may define new application areas of the optoacoustic technology in preclinical research and clinical practice.

The exclusive combination of high optical contrast and excellent spatial resolution makes optoacoustics (photoacoustics) ideal for simultaneously ...

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Bioengineering

10.6K visualizações.  Helmholtz Zentrum München. We provide herein a detailed description of the experimental protocol for imaging with a newly developed hand-held optoacoustic (photoacoustic) system for three-dimensional functional and molecular imaging in real time. The demonstrated powerful performance and versatility may define new application areas of the optoacoustic technology in preclinical research and clinical practice.

Vídeo: Universal Hand-held Three-dimensional Optoacoustic Imaging Probe for Deep Tissue Human Angiography and Functional Preclinical Studies in Real Time