Name: ultrasound-based pulse wave velocity evaluation in mice
Uploaded: 2017-02-14T13:00:00
Description: Watch this Scientific Journal Video about Ultrasound-based Pulse Wave Velocity Evaluation in Mice Video at JoVE.com

Animal experiments were performed in accordance with the European Directive (2010/63/UE) and the Italian law (D.Lvo 26/2014), and it followed principles of laboratory animal care. The Local Ethical Approval Panel approved the study.
1. Imaging Procedure
<ol>
	<li>Place the mouse in an anesthesia induction chamber filled with 2.5% isoflurane in 1 L/min pure oxygen. Verify the depth of anesthesia by unresponsiveness to toe pinch.</li>
	<li>Place the animal on a temperature controlled board in a supine position. Mo...

<ol>
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W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Determination+of+wave+speed+and+wave+separation+in+the+arteries+using+diameter+and+velocity.">Determination of wave speed and wave separation in the arteries using diameter and velocity.</a> J Biomech. 43 (3), 455-462 (2010).</li><li>Borlotti, A., Khir, A. W., Rietzschel, E. R., De Buyzere, M. L., Vermeersch, S., Segers, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Noninvasive+determination+of+local+pulse+wave+velocity+and+wave+intensity:+changes+with+age+and+gender+in+the+carotid+and+femoral+arteries+of+healthy+human.">Noninvasive determination of local pulse wave velocity and wave intensity: changes with age and gender in the carotid and femoral arteries of healthy human.</a> J Appl Physiol. 113 (5), 727-735 (2012).</li><li>Ch&#233;rin, E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ultrahigh+frame+rate+retrospective+ultrasound+microimaging+and+blood+flow+visualization+in+mice+in+vivo.">Ultrahigh frame rate retrospective ultrasound microimaging and blood flow visualization in mice in vivo.</a> Ultrasound Med Biol. 32 (5), 683-691 (2006).</li><li>Gemignani, V., Faita, F., Ghiadoni, L., Poggianti, E., Demi, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+system+for+real-time+measurement+of+the+brachial+artery+diameter+in+B-mode+ultrasound+images.">A system for real-time measurement of the brachial artery diameter in B-mode ultrasound images.</a> IEEE Trans Med Imaging. 26 (3), 393-404 (2006).</li><li>Di Lascio, N., Stea, F., Kusmic, C., Sicari, R., Faita, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Non-invasive+assessment+of+pulse+wave+velocity+in+mice+by+means+of+ultrasound+images.">Non-invasive assessment of pulse wave velocity in mice by means of ultrasound images.</a> Atherosclerosis. 237 (1), 31-37 (2014).</li><li>Nichols, W. 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In this study, an image processing algorithm based on the lnD-V loop for PWV assessment in mice has been described in detail. The proposed approach is based on the processing of US images only and, thus, could represent a valid alternative to existing techniques6,13 for the evaluation of arterial stiffness in mouse models. In fact, conversely to invasive methods6 which are based on the acquisition of intra-arterial pressure signals and req...

Mouse models are increasingly employed for the investigation of cardiovascular disease (CVD) and particularly used in longitudinal studies which allow the characterization of different phases of disease development1. Elastic properties of large arteries are related to different pathological conditions; from a technical point of view, arterial stiffness can be assessed by measuring pulse wave velocity (PWV), which represents the speed with which the pulse wave travels in a conduit vessel2. Because of its clinical significance, it is increasingly measured even in preclinical small animal models3.
Different techniques are available for assessing PWV in mice. Invasive approaches are based on the use of catheter-tip pressure transducers. PWV is assessed by acquiring pressure signals at two different arterial sites and dividing the distance between the two measurement sites by the time shift between the signals4. The main disadvantage related to these kinds of techniques is that they require animal sacrifice for the evaluation of the distance between the two measurement sites and, thus, cannot be used in longitudinal studies. To overcome this limitation, non-invasive approaches, based on different imaging techniques, have been developed. Previous studies have reported PWV assessments in mice obtained by applying the transit time method on velocity-encoded magnetic resonance imaging data5 and Pulsed-Doppler signals6. However, the PWV value obtained with these methods is a regional evaluation of arterial stiffness. In fact, it represents an average value, accounting for different arteries in terms of size and elastic properties. In addition, these kinds of evaluations require the assessment of the distance between the two measurements sites which is a source of error that could influence the final result.
PWV can be assessed using the diameter-velocity (lnD-V) loop7. This method is based on the simultaneous evaluation of diameter and flow velocity values in a selected vessel. According to this approach, the lnD-V loop is obtained by plotting natural logarithm diameter values vs mean velocity values and PWV is estimated by calculating the slope of the linear part of the obtained loop corresponding to the early systolic phase. With regard to the practical implementation of this method, previous works have already reported results about its application in an in vitro set-up system7 and its use for the assessment of both carotid and femoral PWV in humans8.
The principal aim of the present study is to provide a detailed description of an image processing algorithm that provides a non-invasive arterial PWV measurement in mice using US images only. The proposed approach allows the evaluation of local arterial stiffness by means of the processing of both B-mode and Pulsed-Wave Doppler (PW-Doppler) images and can be applied on arteries of key importance, such as the abdominal aorta.

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		<tr height="41">
			<td height="41" style="height:41px;width:216px;">VEVO2100</td>
			<td style="width:260px;">FUJIFILM VisualSonics Inc, Toronto, Canada</td>
			<td style="width:119px;"></td>
			<td style="width:177px;">micro-ultrasound equipment</td>
		</tr>
		<tr height="32">
			<td height="32" style="height:32px;">MS250 Ultrasound Probe</td>
			<td style="width:260px;">FUJIFILM VisualSonics Inc, Toronto, Canada</td>
			<td style="width:119px;"></td>
			<td>micro-ultrasound probe</td>
		</tr>
		<tr height="55">
			<td height="55" style="height:55px;width:216px;">EKV Software</td>
			<td style="width:260px;">FUJIFILM VisualSonics Inc, Toronto, Canada</td>
			<td style="width:119px;"></td>
			<td>Software</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Matlab R2015a&#160;</td>
			<td style="width:260px;">MathWorks Inc, Natick, MA, USA</td>
			<td style="width:119px;"></td>
			<td>Software</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Conductive Paste</td>
			<td style="width:260px;">Chosen by the operator</td>
			<td style="width:119px;"></td>
			<td>Laboratory material</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Petroleum Jelly</td>
			<td style="width:260px;">Chosen by the operator</td>
			<td style="width:119px;"></td>
			<td>Laboratory material</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Depilatory Cream</td>
			<td style="width:260px;">Chosen by the operator</td>
			<td style="width:119px;"></td>
			<td>Laboratory material</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Acoustic Coupling Gel&#160;</td>
			<td style="width:260px;">Chosen by the operator</td>
			<td style="width:119px;"></td>
			<td>Laboratory material</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Developed Matlab Software</td>
			<td style="width:260px;"></td>
			<td style="width:119px;"></td>
			<td>The authors are willing to collaborate with those researchers who are interested in the software and to make the software available under their supervision</td>
		</tr>
	</tbody>
</table>

ultrasound-based pulse wave velocity evaluation in mice

Arterial stiffness can be evaluated by calculating pulse wave velocity (PWV), i.e., the speed with which the pulse wave travels in a conduit vessel. This parameter is being increasingly investigated in small rodent models in which it is used for assessing alterations in vascular function related to particular genotypes/treatments or for characterizing cardiovascular disease progression. This protocol describes an image processing algorithm which leads to non-invasive arterial PWV measurement in mice using ultrasound (US) images only. The proposed technique has been used to assess abdominal aorta PWV in mice and evaluate its age-associated changes.
Abdominal aorta US scans are obtained from mice under gaseous anesthesia using a specific US device equipped with high-frequency US probes. B-mode and Pulse-Wave Doppler (PW-Doppler) images are analyzed in order to obtain diameter and mean velocity instantaneous values, respectively. For this purpose, edge detection and contour tracking techniques are employed. The single-beat mean diameter and velocity waveforms are time aligned and combined in order to achieve the diameter-velocity (lnD-V) loop. PWV values are obtained from the slope of the linear part of the loop, which corresponds to the early systolic phase.
With the present approach, anatomical and functional information about the mouse abdominal aorta can be non-invasively achieved. Requiring the processing of US images only, it may represent a useful tool for the non-invasive characterization of different arterial sites in the mouse in terms of elastic properties. The application of the present technique can be easily extended to other vascular districts, such as the carotid artery, thus providing the possibility to obtain a multi-site arterial stiffness assessment.

The proposed approach has been applied to mice abdominal aorta in a previous study11. The following figures show the results of the application of the described approach on real mice images. These data are from a single animal (wild type mice, 13 weeks old, strain: C57BL6, weight: 33 g) In particular, Figure 1 represents the result of the analysis of the US images. Edge detection and contour tracking techniques applied to B-mode images acquired wit...

Watch this Scientific Journal Video about Ultrasound-based Pulse Wave Velocity Evaluation in Mice Video at JoVE.com

Ultrasound-based Pulse Wave Velocity Evaluation in Mice Video (Video) | JoVE

Arterial stiffness represents a key factor in cardiovascular disease and pulse wave velocity (PWV) can be considered as a surrogate index for arterial stiffness. This protocol describes an image processing algorithm for calculating PWV in mice based on ultrasound image processing that is applicable at different arterial sites.

Ultrasound-based Pulse Wave Velocity Evaluation in Mice

Arterial stiffness can be evaluated by calculating pulse wave velocity (PWV), i.e., the speed with which the pulse wave travels in a conduit vessel. This ...

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