Name: label-free imaging of aortic blood and lipids
Uploaded: 2023-04-30T06:58:46.000Z
Duration: 8 min 38 s
Channel: JoVE

The following procedure describes the methods needed to set up VPAT for blood and lipid imaging of the infrarenal aorta in apolipoprotein-E deficient (apoE-/-) mice.
1. Laser-ultrasound Coupling
<ol>
	<li>Obtain a Nd:YAG pulsed optical parametric oscillator laser and an ultrasound system. Acquire a pulse generator, 1 BNC cable, and a D connector attached to two BNC cables.</li>
	<li>Using the D connector set-up, attach the &#39;Fire&#39; BNC cable to port A of the pulse generator, and &#39;Q-switch&#39; to port B of the pulse generator. Finally, attach a BNC cable from port C to &#39;trigger in&#39; on the back of the ultrasound system.</li>
	<li>Align the fiber optic cable with the laser and attach the fiber ends to the sides of the 40 MHz ultrasound transducer.</li>
	<li>Adjust the delay of ports A, B, and C to the values listed here (Port A: 0.00000000, Port B: 0.00021440, Port C: 0.00000910). Set ports A and B to inverted signal and port C to normal signal.</li>
</ol>
2. Animal Preparation and Image Acquisition
<ol>
	<li>Anesthetize an apoE-/- mouse using 3% isoflurane in an anesthesia induction chamber. Once the animal is anesthetized move the mouse to a nose cone to deliver 1-2% isoflurane.</li>
	<li>Apply eye lubricate to the animals eyes to prevent corneal desiccation. Tape the mouse&#39;s paws to electrodes built into the heated stage to monitor animal&#39;s respiration and heart rate. Finally, insert rectal probe to monitor body temperature.</li>
	<li>Apply depilatory cream to remove hair from the animal&#39;s abdomen. Wipe off after 30 s with a gauze pad.</li>
	<li>Place the ultrasound transducer on the animal&#39;s abdomen and locate the infrarenal aorta. The left renal vein and the aortic trifurcation into the tail artery are two landmarks that will help the user locate this area.</li>
	<li>Run the laser to output 1100 nm light to target blood followed by 1210 nm light to target lipid. Use appropriate laser safety goggles when the laser is in use.</li>
</ol>

VPAT is a rapid, noninvasive, label-free method to image blood and lipid accumulation in vivo. By delivering pulsed laser light to tissue, acoustic propagations were induced to obtain relative density and locate biological components. When coupled with ultrasound imaging, compositional, as well as structural and hemodynamic information from tissue, can be resolved. A current limitation of this technique is its penetration depth, which is roughly 3 mm for lipid-based imaging. While this is better than current opt...

photoacoustic tomography to image blood and lipids in the infrarenal aorta

Photoacoustic Tomography to Image Blood and Lipids in the Infrarenal Aorta

Source: Gurneet S. Sangha and <a href="https://www.jove.com/author/Craig+J._Goergen">Craig J. Goergen</a>, Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana
Photoacoustic tomography (PAT) is an emerging biomedical imaging modality that utilizes light generated acoustic waves to obtain compositional information from tissue. PAT can be used to image blood and lipid components, which is useful for a wide variety of applications, including cardiovascular and tumor imaging. Currently used imaging techniques have inherent limitations that restrict their use with researchers and physicians. For example, long acquisition times, high costs, use of harmful contrast, and minimal to high invasiveness are all factors that limit the use of various modalities in the laboratory and clinic. Currently, the only comparable imaging techniques to PAT are emerging optical techniques. But these also have disadvantages, such as limited depth of penetration and the need for exogenous contrast agents. PAT provides meaningful information in a rapid, noninvasive, label-free manner. When coupled with ultrasound, PAT can be used to obtain structural, hemodynamic, and compositional information from tissue, thereby complementing currently used imaging techniques. The advantages of PAT illustrate its capabilities to make an impact in both the preclinical and clinical environment.

Here, VPAT methods were used to perform lipid and blood specific imaging in vivo. By coupling a laser and ultrasound system, light was delivered to tissue and the resulting acoustic waves were detected. Ultrasound imaging allowed us to obtain structural information of the infrarenal aorta (Figure 1a) that can be used to better interpret VPAT compositional information. Specifically, a 1100 nm light was used to image blood within the aorta (<strong cla...

Source: Gurneet S. Sangha and Craig J. Goergen, Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana
Photoacoustic ...

Photoacoustic tomography, PAT, sometimes referred to as optoacoustic tomography, is an emerging biomedical imaging modality that utilizes light-generated acoustic waves to obtain compositional information from a tissue.
Photoacoustic tomography, or PAT, uses particular wavelengths of light to image specific components of the tissue. This is useful for a wide variety of preclinical and clinical applications, such as monitoring lipid-based disease progression.
Currently used imaging techniques are inherently limited in terms of acquisition times, depth of penetration, use of harmful contrasting agents, and costs. PAT, on the other hand, is a rapid, non-invasive, and contrast agent-free technique, which when combined with existing imaging modalities like ultrasound, can provide structural and compositional information simultaneously.
This video will illustrate the basic principles of vibrational PAT and the methodology to set up blood and lipid imaging in mice. Next, we will demonstrate how to interpret VPAT images in conjunction with ultrasound, followed by a few applications of the technique.
Let us begin by discussing the fundamentals of this imaging technique.
During VPAT imaging,

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label-free imaging of aortic blood and lipids

Photoacoustic tomography (PAT) is a biomedical imaging method that uses light-generated sound waves to study tissue composition. It can detect blood and lipid components in the infrarenal aorta, the lower part of the aorta below the kidneys. This makes PAT useful for cardiovascular research and tumor imaging.

PAT addresses several limits of current imaging methods. Many existing techniques can take a long time, cost a lot, use harmful contrast agents, or require more invasive procedures. Some newer optical methods also have limits, including shallow penetration depth and the need for external contrast agents.

PAT offers meaningful tissue information in a rapid, noninvasive, and label-free way. When it is combined with ultrasound, it can provide structural, hemodynamic, and compositional information from tissue. This combination helps PAT complement other imaging approaches in both preclinical and clinical settings.

Label-Free Imaging of Aortic Blood and Lipids

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Learn how photoacoustic tomography uses light-generated sound waves to image blood and lipids in the infrarenal aorta in a rapid, label-free way.

Label-Free Imaging of Aortic Blood and Lipids

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