Name: two-dimensional x-ray angiography to examine fine vascular structure using a silicone rubber injection compound
Uploaded: 2019-01-07T14:00:00
Description: Watch this Scientific Journal Video about Two-Dimensional X-Ray Angiography to Examine Fine Vascular Structure Using a Silicone Rubber Injection Compound at JoVE.com

This work (2017R1A2B1006403) was supported by the Mid-Career Researcher Program through a National Research Foundation grant funded by the Korean government (Ministry of Science and ICT).

All procedures, including animal subjects, have been approved by the Institutional Animal Care and Use Committees of Seoul National University Hospital (IACUC No. 10-0184). This protocol is optimized for research on flap vasculature. This example is based on a four-territory flap model in our previous reports.
1. Establishing a Flap Condition
NOTE: It is important to generate a vascular change in a rat flap model 4 to 5 days before visible estimation...

<ol>
	<li>Taylor, G. I., Minabe, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Angiosomes+of+the+Mammals+and+Other+Vertebrates.">The Angiosomes of the Mammals and Other Vertebrates.</a> Plastic and Reconstructive Surgery. 89 (2), 181-215 (1992).</li><li>Taylor, G. I., Palmer, J. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+vascular+territories+(angiosomes)+of+the+body:+experimental+study+and+clinical+applications.">The vascular territories (angiosomes) of the body: experimental study and clinical applications.</a> British Journal of Plastic Surgery. 40 (2), 113-141 (1987).</li><li>Geddes, C. R., Morris, S. F., Neligan, P. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Perforator+flaps:+evolution,+classification,+and+applications.">Perforator flaps: evolution, classification, and applications.</a> Annals of Plastic Surgery. 50 (1), 90-99 (2003).</li><li>Saint-Cyr, M., Schaverien, M. V., Rohrich, R. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Perforator+Flaps:+History,+Controversies,+Physiology,+Anatomy,+and+Use+in+Reconstruction.">Perforator Flaps: History, Controversies, Physiology, Anatomy, and Use in Reconstruction.</a> Plastic and Reconstructive Surgery. 123 (4), 132-145 (2009).</li><li>Lie, K. H., Taylor, G. I., Ashton, M. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hydrogen+peroxide+priming+of+the+venous+architecture:+a+new+technique+that+reveals+the+underlying+anatomical+basis+for+venous+complications+of+DIEP,+TRAM,+and+other+abdominal+flaps.">Hydrogen peroxide priming of the venous architecture: a new technique that reveals the underlying anatomical basis for venous complications of DIEP, TRAM, and other abdominal flaps.</a> Plastic and Reconstructive Surgery. 133 (6), 790-804 (2014).</li><li>Chang, H., Nobuaki, I., Minabe, T., Nakajima, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparison+of+Three+Different+Supercharging+Procedures+in+a+Rat+Skin+Flap+Model.">Comparison of Three Different Supercharging Procedures in a Rat Skin Flap Model.</a> Plastic and Reconstructive Surgery. 113 (1), 277-283 (2004).</li><li>Chang, H., Minn, K. W., Imanishi, N., Minabe, T., Nakajima, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+Venous+Superdrainage+on+a+Four-Territory+Skin+Flap+Survival+in+Rats.">Effect of Venous Superdrainage on a Four-Territory Skin Flap Survival in Rats.</a> Plastic and Reconstructive Surgery. 119 (7), 2046-2051 (2007).</li><li>Rozen, W. M., Stella, D. L., Ashton, M. W., Phillips, T. J., Taylor, G. I. <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+CT+angiography:+a+new+technique+for+imaging+microvascular+anatomy.">Three-dimensional CT angiography: a new technique for imaging microvascular anatomy.</a> Clinical Anatomy. 20 (8), 1001-1003 (2007).</li><li>Taylor, G. I., Chubb, D. P., Ashton, M. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=True+and+"choke"+anastomoses+between+perforator+angiosomes:+part+i.+anatomical+location.">True and "choke" anastomoses between perforator angiosomes: part i. anatomical location.</a> Plastic and Reconstructive Surgery. 132 (6), 1447-1456 (2013).</li><li>Feng, J., Fitz, Y., 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=Catheterization+of+the+carotid+artery+and+jugular+vein+to+perform+hemodynamic+measures,+infusions+and+blood+sampling+in+a+conscious+rat+model.">Catheterization of the carotid artery and jugular vein to perform hemodynamic measures, infusions and blood sampling in a conscious rat model.</a> Journal of Visualized Experiments. (95), e51881 (2015).</li><li>Park, S. O., Cho, J., Imanishi, N., Chang, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+distal+venous+drainage+on+the+survival+of+four-territory+flaps+with+no+pedicle+vein:+Results+from+a+rat+model.">Effect of distal venous drainage on the survival of four-territory flaps with no pedicle vein: Results from a rat model.</a> Journal of Plastic, Reconstructive &amp; Aesthetic Surgery. 71 (3), 410-415 (2018).</li><li>Park, S. O., Chang, H., Imanishi, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+free+serratus+anterior+artery+perforator+flap-A+case+report+and+anatomic+study.">The free serratus anterior artery perforator flap-A case report and anatomic study.</a> Microsurgery. 36 (4), 339-344 (2016).</li><li>Imanishi, N., Nakajima, H., Minabe, T., Chang, H., Aiso, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Anatomical+relationship+between+arteries+and+veins+in+the+paraumbilical+region.">Anatomical relationship between arteries and veins in the paraumbilical region.</a> British Journal of Plastic Surgery. 56 (6), 552-556 (2003).</li><li>Schaverien, M., Saint-Cyr, M., Arbique, G., Rohrich, R. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Three-+and+four-dimensional+arterial+and+venous+anatomies+of+the+thoracodorsal+artery+perforator+flap.">Three- and four-dimensional arterial and venous anatomies of the thoracodorsal artery perforator flap.</a> Plastic and Reconstructive Surgery. 121 (5), 1578-1587 (2008).</li><li>Schaverien, M., Saint-Cyr, M., Arbique, G., Hatef, D., Brown, S. A., Rohrich, R. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Three-+and+Four-Dimensional+Computed+Tomographic+Angiography+and+Venography+of+the+Anterolateral+Thigh+Perforator+Flap.">Three- and Four-Dimensional Computed Tomographic Angiography and Venography of the Anterolateral Thigh Perforator Flap.</a> Plastic and Reconstructive Surgery. 121 (5), 1685-1696 (2008).</li></ol>

Silicone rubber injection compound angiography can be performed easily, does not require expensive equipment, and offers many advantages. In contrast to the preoperative and intraoperative evaluations of patients, experiments using animals and cadavers can provide details on specific conditions, enabling more diverse and in-depth studies. The flap model using rats is particularly valuable to clinicians because changes in various contexts can be observed before clinical applications6,<su...

Examining vascular structures such as arteries and veins is an important area of interest, particularly in reconstructive surgery. In this field, flap surgery is widely performed. Therefore, angiographic imaging is actively used to study the flap territory, angiosome, and vascular supply of fresh tissue1. Specifically, there have been continuous efforts to observe the fine vasculature, including fine vessels such as perforators (vessels emerging from deep vessels reaching the skin), and choke vessels (connecting vessels between adjacent angiosomes)2. These two types of vessels are important in the perforator flap reconstruction field and are the main focus of the research3,4.
Various materials are used in angiography. First, there is India ink, which is helpful in observing the gross anatomy of blood vessels. However, it is radiolucent, so angiographic images cannot be obtained. The more commonly-used radiopaque materials are lead oxide and barium. However, toxicity is a crucial drawback of lead oxide, and it is inconvenient to use when mixed with water because of its powdered form. Barium is free from toxicity; however, it is not very feasible, as it should be used after dilution. Both of these radiopaque materials cannot cross capillaries; therefore, if a whole vascular structure must be analyzed, it is necessary to inject them into the artery and vein separately5. In addition, the two materials cause dye leakage during anatomical dissection, so they should be combined with gelatin. Lead oxide-gelatin and barium-gelatin mixtures take at least one day to solidify1,6,7.
Computed tomography (CT) angiography is another widely-used method and can aid in viewing three-dimensional (3D) structures8. However, veins cannot be visualized effectively5. In this modality, clear visualization of the fine vasculature such as choke veins is difficult, except when using specific equipment. The need for more expensive equipment can be a disadvantage, so CT angiography cannot be utilized in all laboratories. By contrast, the soft tissue X-ray system is relatively cheap and can operate more easily. This system is optimal for viewing soft tissues and can provide higher quality soft tissue images than the simple X-ray system. Although the soft tissue X-ray system itself cannot show 3D images, it can help visualize fine vascular structures more clearly than CT angiography. Therefore, we have used the soft tissue X-ray system in many experiments, particularly in various flap models and basic anatomy2,9.
Finally, the use of silicone rubber injection compound angiography has numerous advantages. Because various color agents are prepared, it can be injected and display distinguishable colors such as India ink. Therefore, simultaneously studying the gross anatomy and angiography is possible. It can both pass through capillaries and allow veins to be visualized, making examinations of fine vascular structures possible. Unlike the gelatin mixture, the silicone rubber injection compound solidifies within a short time period, approximately 15 minutes, without any additional procedures. The entire process is summarized in the schematic image in Figure 1.

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		<col />
	</colgroup>
	<tbody>
		<tr height="40">
			<td height="40" style="height:40px;width:339px;">MICROFIL Silicone Rubber Injection Compounds</td>
			<td style="width:151px;">Flow Tech Inc.</td>
			<td style="width:115px;">MV-112</td>
			<td style="width:273px;">White color agent</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:339px;">MICROFIL Silicone Rubber Injection Compounds</td>
			<td style="width:151px;">Flow Tech Inc.</td>
			<td style="width:115px;">MV-117</td>
			<td style="width:273px;">Orange color agent</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:339px;">MICROFIL Silicone Rubber Injection Compounds</td>
			<td style="width:151px;">Flow Tech Inc.</td>
			<td style="width:115px;">MV-120</td>
			<td style="width:273px;">Blue color agent</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:339px;">MICROFIL Silicone Rubber Injection Compounds</td>
			<td style="width:151px;">Flow Tech Inc.</td>
			<td style="width:115px;">MV-122</td>
			<td style="width:273px;">Yellow color agent</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:339px;">MICROFIL Silicone Rubber Injection Compounds</td>
			<td style="width:151px;">Flow Tech Inc.</td>
			<td style="width:115px;">MV-130</td>
			<td style="width:273px;">Red color agent</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:339px;">MICROFIL Silicone Rubber Injection Compounds</td>
			<td style="width:151px;">Flow Tech Inc.</td>
			<td style="width:115px;">MV-132</td>
			<td style="width:273px;">Clear agent</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:339px;">MICROFIL Silicone Rubber Injection Compounds</td>
			<td style="width:151px;">Flow Tech Inc.</td>
			<td style="width:115px;">MV-Diluent</td>
			<td style="width:273px;">Diluent</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:339px;">MICROFIL CP-101 For Cast Corrosion Preparations</td>
			<td style="width:151px;">Flow Tech Inc.</td>
			<td style="width:115px;">CP-101</td>
			<td style="width:273px;">Curing agent</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:339px;">SOFTEX X-ray film photographing inspection equipment</td>
			<td style="width:151px;">SOFTEX</td>
			<td style="width:115px;">CMB-2</td>
			<td style="width:273px;">Soft tissue x-ray system</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:339px;">Film&#160;</td>
			<td style="width:151px;">Fujifilm</td>
			<td style="width:115px;">Industrial X-ray Film (FR 12x16.5cm)</td>
			<td style="width:273px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:339px;">Automatic Development Machine</td>
			<td style="width:151px;">Fujifilm</td>
			<td style="width:115px;">FPM 2800</td>
			<td style="width:273px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:339px;">Rat&#160;</td>
			<td style="width:151px;"></td>
			<td style="width:115px;"></td>
			<td style="width:273px;">Sprague-Dawley rat weighing 200-250 g</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:339px;">Three-way stopcock</td>
			<td style="width:151px;"></td>
			<td style="width:115px;"></td>
			<td style="width:273px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:339px;">24-guage catheter</td>
			<td style="width:151px;"></td>
			<td style="width:115px;"></td>
			<td style="width:273px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:339px;">Image J</td>
			<td style="width:151px;">National Institutes of Health&#160;</td>
			<td style="width:115px;"></td>
			<td style="width:273px;">https://imagej.nih.gov/ij/</td>
		</tr>
	</tbody>
</table>

two-dimensional x-ray angiography to examine fine vascular structure using a silicone rubber injection compound

Angiography is an essential tool for the study of vascular structures in various research fields. The aim of this study is to introduce a simple angiographic method for examining the fine vascular structure of unfixed, fresh tissue using a silicone rubber injection compound and soft tissue X-ray system. This study is especially focused on flap territories used in reconstructive surgery. This study employs angiography with a silicone rubber injection compound in various experimental conditions using Sprague-Dawley rats. First, 15 mL of MV compound and 15 mL of diluent is mixed. Then, 1.5 mL of the curing agent is prepared, and a 24G catheter is cannulated in the common carotid artery of the rat. A three-way stopcock is then connected to a catheter, and the radiopaque agent, after being mixed with the prepared curing agent, is injected immediately without spillage. Finally, as the agent solidifies, the specimen is harvested, and an angiographic image is obtained using a soft tissue X-ray system. This method indicates that high-quality angiography showing fine vascular structures can be easily and simply obtained within in a short period of time.

Through following this protocol, the flap vascularity of the Sprague-Dawley rat was examined. A circumferential skin flap from the lower abdomen to the back that measured 4 x 12 cm was marked based on our previous reports. Each specimen was in a different vascular condition.
All the flaps were elevated based on the deep circumflex iliac artery (DCIA) and vein and then supercharged with arteries from various locations. Group 1 wa...

Watch this Scientific Journal Video about Two-Dimensional X-Ray Angiography to Examine Fine Vascular Structure Using a Silicone Rubber Injection Compound at JoVE.com

Two-Dimensional X-Ray Angiography to Examine Fine Vascular Structure Using a Silicone Rubber Injection Compound

This study presents a simple two-dimensional angiographic method to examine fine vascular structures using a silicone rubber injection compound and soft tissue X-ray system.

Angiography is an essential tool for the study of vascular structures in various research fields. The aim of this study is to introduce a simple ...

This method can help answer key questions in the reconstructive surgery field about how to perform the perforative lift surgery. Main advantage of this technique is that the variation of fine vascular structures, such as choke vessels, can be performed easily under various vascular flap conditions. To establish a flap condition, confirm the appropriate level of sedation by a lack of response to toe pinch in an anesthetized 200 to 250 gram 7 week old male Sprague-Dawley rat and mark a 4 by 12 centimeter circumferential skin flap design from the lower abdomen to the back.With the center of the flap halfway between the xiphoid process and the penis. Use a surgical blade to make the incision as marked and use scissors to dissect the flap, including the skin and panniculus carnosus. Dissect around the vascular pedicle at the lower abdomen and use a microscope or surgical loop to expose the vascular tissue.Ligate the vessels and divide the flap along the dorsal midline. The return the flap to its original position and secure the flap with the skin stapler. It is important to make flaps that have obvious vascular territories to allow changes to be easily made to the vascular condition of the flap as required for doing experimental protocol.On the day of the procedure, make a 2 centimeter midline skin incision between the scapulae and use mosquito forceps and blunt scissors to expose the salivary gland complex. After longitudinal dissection of the omohyoid muscle, dissect around the common carotid artery and use black silk to retract the cephalic and caudal sides of the artery. Make a tie on the proximal suture and keep traction to maintain engorgement of the artery and loosely place the caudal suture.The insert a 24 gauge catheter into the prepared artery and secure the catheter with the caudal suture. Connect a three way stopcock to the catheter and use an empty syringe to apply negative pressure to the catheter confirming a back flow of blood into the catheter. Next, inject 25 to 30 milliliters of freshly prepared silicone rubber injection compound into the catheter until the colors of the eye and foot have changed.When all of the compound has been injected, lock the three way stopcock and allow the agent to solidify for about 15 minutes. Then place a protective barrier around the syringe of compound so as not to contaminate the radio opaque agent. And remove the syringe from the stopcock.To harvest the specimen, use a surgical blade to make an incision in the panniculus carnosus one centimeter away from the flap to prevent damage to any vascular structures inside the flap and dissect around the flap below the panniculus carnosus plane. Then use scissors to harvest the tissue including the flap and and vascular pedicle within the flap and use a five o silk suture to ligate the pedicle of the flap, separating the flap from the body. Silicone rubber injection angiography clearly reveals fine vascular structures, allowing the acquisition of high-quality angiographic images of the dilated choke veins even under otherwise difficult imaging conditions.For example, in this representative experiment, it can be observed that all of the flaps were elevated based on the deep circumflex iliac artery and vein before being supercharged with arteries from various locations. If an entire flap is divided into four zones as the standard with the main vessel charging the flap territory, the angiographic agent that reaches the main vessel charges the next distal zone beyond the supercharging artery. The dilated choke vein can also be observed, even though it was not seen in the normal skin angiography.Once mastered, this technique can be completed in one hour per rat if it is performed properly. While attempting this procedure, it is important to remember not to contaminate or spill the angiographic agent during the injection. After watching this video, you should have a good understanding of how to make a specific condition flap and to perform an angiography.

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Medicine

Guide Wire Assisted Catheterization and Colored Dye Injection for Vascular Mapping of Monochorionic Twin Placentas

Monochorionic (MC) twin pregnancies are associated with significantly higher morbidity and mortality rates than dichorionic twins. Approximately 50% of MC twin pregnancies develop complications arising from the shared placenta and associated vascular connections1. Severe twin-to-twin syndrome (TTTS) is reported to account for approximately 20% of these complications2,3. Inter-twin vascular connections occur in almost all MC placentas and are related to the prognosis and outcome of these high-risk twin pregnancies. The number, size and type of connections have been implicated in the development of TTTS and other MC twin conditions. Three types of inter-twin vascular connections occur: 1) artery to vein connections (AVs) in which a branch artery carrying deoxygenated blood from one twin courses along the fetal surface of the placenta and dives into a placental cotyledon. Blood flows via a deep intraparenchymal capillary network into a draining vein that emerges at the fetal surface of the placenta and brings oxygenated blood toward the other twin. There is unidirectional flow from the twin supplying the afferent artery toward the twin receiving the efferent vein; 2) artery to artery connections (AAs) in which a branch artery from each twin meets directly on the superficial placental surface resulting in a vessel with pulsatile bidirectional flow, and 3) vein to vein connections (VVs) in which a branch vein from each twin meets directly on the superficial placental surface allowing low pressure bidirectional flow. In utero obstetric sonography with targeted Doppler interrogation has been used to identify the presence of AV and AA connections4. Prenatally detected AAs that have been confirmed by postnatal placental injection studies have been shown to be associated with an improved prognosis for both twins5. Furthermore, fetoscopic laser ablation of inter-twin vascular connections on the fetal surface of the shared placenta is now the preferred treatment for early, severe TTTS. 
Postnatal placental injection studies provide a valuable method to confirm the accuracy of prenatal Doppler ultrasound findings and the efficacy of fetal laser therapy6. Using colored dyes separately hand-injected into the arterial and venous circulations of each twin, the technique highlights and delineates AVs, AAs, and VVs. This definitive demonstration of MC placental vascular anatomy may then be correlated with Doppler ultrasound findings and neonatal outcome to enhance our understanding of the pathophysiology of MC twinning and its sequelae. Here we demonstrate our placental injection technique.

Vascular mapping of monochorionic (MC) twin placentas after birth provides a means for detailed demonstration of vascular connections between the twins&#x2019; circulations. 
Imbalance of these connections is thought to play a pivotal role in the development of complications of MC twinning including twin-to-twin transfusion syndrome.

Monochorionic (MC) twin pregnancies are associated with significantly higher morbidity and mortality rates than dichorionic twins. Approximately 50% of MC ...

X-ray Dose Reduction through Adaptive Exposure in Fluoroscopic Imaging

X-ray fluoroscopy is widely used for image guidance during cardiac intervention. However, radiation dose in these procedures can be high, and this is a significant concern, particularly in pediatric applications. Pediatrics procedures are in general much more complex than those performed on adults and thus are on average four to eight times longer1. Furthermore, children can undergo up to 10 fluoroscopic procedures by the age of 10, and have been shown to have a three-fold higher risk of developing fatal cancer throughout their life than the general population2,3.
We have shown that radiation dose can be significantly reduced in adult cardiac procedures by using our scanning beam digital x-ray (SBDX) system4-- a fluoroscopic imaging system that employs an inverse imaging geometry5,6 (Figure 1, Movie 1 and Figure 2). Instead of a single focal spot and an extended detector as used in conventional systems, our approach utilizes an extended X-ray source with multiple focal spots focused on a small detector. Our X-ray source consists of a scanning electron beam sequentially illuminating up to 9,000 focal spot positions. Each focal spot projects a small portion of the imaging volume onto the detector. In contrast to a conventional system where the final image is directly projected onto the detector, the SBDX uses a dedicated algorithm to reconstruct the final image from the 9,000 detector images.
For pediatric applications, dose savings with the SBDX system are expected to be smaller than in adult procedures. However, the SBDX system allows for additional dose savings by implementing an electronic adaptive exposure technique. Key to this method is the multi-beam scanning technique of the SBDX system: rather than exposing every part of the image with the same radiation dose, we can dynamically vary the exposure depending on the opacity of the region exposed. Therefore, we can significantly reduce exposure in radiolucent areas and maintain exposure in more opaque regions. In our current implementation, the adaptive exposure requires user interaction (Figure 3). However, in the future, the adaptive exposure will be real time and fully automatic.
We have performed experiments with an anthropomorphic phantom and compared measured radiation dose with and without adaptive exposure using a dose area product (DAP) meter. In the experiment presented here, we find a dose reduction of 30%.

We are developing a dynamic adaptive exposure technique using our scanning beam digital X-ray system. Rather than exposing an object uniformly, the exposure is adapted depending on the opacity of the object. Here we show an experiment on an anthropomorphic phantom that resulted in a dose saving of 30%.

X-ray fluoroscopy is widely used for image guidance during cardiac intervention. However, radiation dose in these procedures can be high, and this is a ...

Segmentation and Measurement of Fat Volumes in Murine Obesity Models Using X-ray Computed Tomography

Obesity is associated with increased morbidity and mortality as well as reduced metrics in quality of life.1 Both environmental and genetic factors are associated with obesity, though the precise underlying mechanisms that contribute to the disease are currently being delineated.2,3 Several small animal models of obesity have been developed and are employed in a variety of studies.4 A critical component to these experiments involves the collection of regional and/or total animal fat content data under varied conditions.
Traditional experimental methods available for measuring fat content in small animal models of obesity include invasive (e.g. ex vivo measurement of fat deposits) and non-invasive (e.g. Dual Energy X-ray Absorptiometry (DEXA), or Magnetic Resonance (MR)) protocols, each of which presents relative trade-offs. Current invasive methods for measuring fat content may provide details for organ and region specific fat distribution, but sacrificing the subjects will preclude longitudinal assessments. Conversely, current non-invasive strategies provide limited details for organ and region specific fat distribution, but enable valuable longitudinal assessment. With the advent of dedicated small animal X-ray computed tomography (CT) systems and customized analytical procedures, both organ and region specific analysis of fat distribution and longitudinal profiling may be possible. Recent reports have validated the use of CT for in vivo longitudinal imaging of adiposity in living mice.5,6 Here we provide a modified method that allows for fat/total volume measurement, analysis and visualization utilizing the Carestream Molecular Imaging Albira CT system in conjunction with PMOD and Volview software packages.

Fat content analysis is routinely conducted in studies utilizing murine obesity models. Emerging methods in small animal CT imaging and analysis are providing for longitudinal detail rich fat content analysis. Here we detail step by step procedures for performing small animal CT imaging, analysis, and visualization.

Obesity is associated with increased morbidity and mortality as well as reduced metrics in quality of life.1 Both environmental and genetic factors are ...

Intranasal Administration of CNS Therapeutics to Awake Mice

Intranasal administration is a method of delivering therapeutic agents to the central nervous system (CNS). It is non-invasive and allows large molecules that do not cross the blood-brain barrier access to the CNS. Drugs are directly targeted to the CNS with intranasal delivery, reducing systemic exposure and thus unwanted systemic side effects1. Delivery from the nose to the CNS occurs within minutes along both the olfactory and trigeminal neural pathways via an extracellular route and does not require drug to bind to any receptor or axonal transport2. Intranasal delivery is a widely publicized method and is currently being used in human clinical trials3.
Intranasal delivery of drugs in animal models allows for initial evaluation of pharmacokinetic distribution and efficacy. With mice, it is possible to administer drugs to awake (non-anesthetized) animals on a regular basis using a specialized intranasal grip. Awake delivery is beneficial because it allows for long-term chronic dosing without anesthesia, it takes less time than with anesthesia, and can be learned and done by many people so that teams of technicians can dose large numbers of mice in short periods. Efficacy of therapeutics administered intranasally in this way to mice has been demonstrated in a number of studies including insulin in diabetic mouse models 4-6 and deferoxamine in Alzheimer's mouse models. 7,8
The intranasal grip for mice can be learned, but is not easy and requires practice, skill, and a precise grip to effectively deliver drug to the brain and avoid drainage to the lung and stomach. Mice are restrained by hand using a modified scruff in the non-dominant hand with the neck held parallel to the floor, while drug is delivered with a pipettor using the dominant hand. It usually takes 3-4 weeks of acclimating to handling before mice can be held with this grip without a stress response. We have prepared this JoVE video to make this intranasal delivery technique more accessible.

A method to intranasally administer drugs to awake mice for the purpose of targeting the brain is described. This method allows for repeat dosing over long periods using intranasal administration of drug without anesthesia, and nose-to-brain delivery with minimal systemic exposure.

Intranasal administration is a method of delivering  therapeutic agents to the central nervous system (CNS). It is  non-invasive and allows large ...

Dual-phase Cone-beam Computed Tomography to See, Reach, and Treat Hepatocellular Carcinoma during Drug-eluting Beads Transarterial Chemo-embolization

The advent of cone-beam computed tomography (CBCT) in the angiography suite has been revolutionary in interventional radiology. CBCT offers 3 dimensional&#160;(3D) diagnostic imaging in the interventional suite and can enhance minimally-invasive therapy beyond the limitations of 2D angiography alone. The role of CBCT has been recognized in transarterial chemo-embolization (TACE) treatment of hepatocellular carcinoma (HCC). The recent introduction of a CBCT technique: dual-phase CBCT (DP-CBCT) improves intra-arterial HCC treatment with drug-eluting beads (DEB-TACE). DP-CBCT can be used to localize liver tumors with the diagnostic accuracy of multi-phasic multidetector computed tomography (M-MDCT) and contrast enhanced magnetic resonance imaging (CE-MRI) (See the tumor), to guide intra-arterially guidewire and microcatheter to the desired location for selective therapy (Reach the tumor), and to evaluate treatment success during the procedure (Treat the tumor). The purpose of this manuscript is to illustrate how DP-CBCT is used in DEB-TACE to see, reach, and treat HCC.

Dual-phase cone-beam computed tomography (DP-CBCT) is a useful intraprocedural imaging technique for transarterial chemo-embolization treatment with drug-eluting beads of hepatocellular carcinoma. DP-CBCT has been used to perform three major steps in oncologic interventional radiology: tumor localization (see), navigation and intraprocedural catheter guidance (reach), and intraprocedural evaluation of treatment success (treat).

The advent of cone-beam computed tomography (CBCT) in the angiography suite has been revolutionary in interventional radiology. CBCT offers 3 ...

Real-time X-ray Imaging of Lung Fluid Volumes in Neonatal Mouse Lung

At birth, the lung undergoes a profound phenotypic switch from secretion to absorption, which allows for adaptation to breathing independently. Promoting and sustaining this phenotype is critically important in normal alveolar growth and gas exchange throughout life. Several in vitro studies have characterized the role of key regulatory proteins, signaling molecules, and steroid hormones that can influence the rate of lung fluid clearance. However, in vivo examinations must be performed to evaluate whether these regulatory factors play important physiological roles in regulating perinatal lung liquid absorption. As such, the utilization of real time X-ray imaging to determine perinatal lung fluid clearance, or pulmonary edema, represents a technological advancement in the field. Herein, we explain and illustrate an approach to assess the rate of alveolar lung fluid clearance and alveolar flooding in C57BL/6 mice at post natal day 10 using X-ray imaging and analysis. Successful implementation of this protocol requires prior approval from institutional animal care and use committees (IACUC), an in vivo small animal X-ray imaging system, and compatible molecular imaging software.

We present a protocol to assess the rate of alveolar fluid clearance or pulmonary edema in neonatal mouse lung using X-ray imaging technology.

At birth, the lung undergoes a profound phenotypic switch from secretion to absorption, which allows for adaptation to breathing independently. Promoting ...

Using the Sleeve Technique in a Mouse Model of Aortic Transplantation - An Instructional Video

Orthotopic aortic transplantation using the sleeve technique reduces injury to the aorta with failure rate of only 10-20%. The time to anastomose the aorta in mice using the sleeve method was short and easy averaging 20 min, permitting studies of iso/allo grafts. The following article describes the aortic transplantation procedure used in our laboratory. The mice were anesthetized with a mixture of 1.5% volume isoflurane and 100% oxygen through a face mask. At this point, the segment of the aorta between the renal arteries and its bifurcation was separated from the vena cava, freely prepared and clampedat the proximal and distal segments with a single silk suture. Prior to the removal of the aorta, a saline solution containing heparin was injected into the inferior vena cava. Then the aorta was cut between the clamps and a saline heparin solution was used to flush the lumen. The sleeve technique with monofilament sutures was used in order to transplant the abdominal aorta in the orthotopic position.

We present an orthotopic aortic transplantation model using the sleeve technique in mice. It is a very rapid anastomosis method, which can be employed in studies of vascular disease.

Orthotopic aortic transplantation using the sleeve technique reduces injury to the aorta with failure rate of only 10-20%. The time to anastomose the ...

Improved Registration of 3D CT Angiography with X-ray Fluoroscopy for Image Fusion During Transcatheter Aortic Valve Implantation

The fusion of 3D anatomical models derived from high-fidelity pre-interventional computed tomography angiography (CTA), and x-ray (XR) fluoroscopy to facilitate anatomical guidance is of huge interest for complex cardiac interventions like TAVI procedures with cerebral protection. Co-registration of CTA and XR has been introduced either based on additional intraoperative non-/contrast-enhanced cone-beam computed tomography (CBCT) or two separate aortograms. With the related increase of radiation exposure and/or contrast agent (CA) dose, a potential additional risk for the patient is introduced. Here, we propose a modified co-registration approach making use of arteriograms of the iliofemoral arteries, routinely performed during the femoral puncture and sheath introduction. On-the-fly refinement of the co-registration during the on-going procedure enables accurate co-registration without any additional angiograms, thus reducing CA, XR dose and procedure time, while simultaneously improving operator confidence and procedure safety.

The aim of this study was to improve the co-registration for image fusion (IF) of pre-interventional CT data with real-time x-ray (XR) fluoroscopy during transfemoral transcatheter aortic valve implantation (TAVI).

The fusion of 3D anatomical models derived from high-fidelity pre-interventional computed tomography angiography (CTA), and x-ray (XR) fluoroscopy to ...

Time-Resolved, Dynamic Computed Tomography Angiography for Characterization of Aortic Endoleaks and Treatment Guidance via 2D-3D Fusion-Imaging

In the United States, more than 80% of all abdominal aortic aneurysms are treated by endovascular aortic aneurysm repair (EVAR). The endovascular approach warrants good early results, but adequate follow-up imaging after EVAR is imperative to maintain long-term positive outcomes. Potential graft-related complications are graft migration, infection, fraction, and endoleaks, with the last one being the most common. The most frequently used imaging after EVAR is computed tomography angiography (CTA) and duplex ultrasound. Dynamic, time-resolved computed tomography angiography (d-CTA) is a reasonably new technique to characterize the endoleaks. Multiple scans are done sequentially around the endograft during acquisition that grants good visualization of the contrast passage and graft-related complications. This high diagnostic accuracy of d-CTA can be implemented into therapy via image fusion and reduce additional radiation and contrast material exposure.
This protocol describes the technical aspects of this modality: patient selection, preliminary image review, d-CTA scan acquisition, image processing, qualitative and quantitative endoleak characterization. The steps of integrating dynamic CTA into intra-operative fluoroscopy using 2D-3D fusion-imaging to facilitate targeted embolization are also demonstrated. In conclusion, time-resolved, dynamic CTA is an ideal modality for endoleak characterization with additional quantitative analysis. It can reduce radiation and iodinated contrast material exposure during endoleak treatment by guiding interventions.

Time-Resolved, Dynamic Computed Tomography Angiography for Characterization of Aortic Endoleaks and Treatment Guidance via 2D-3D Fusion-Imaging

Dynamic computed tomography angiography (CTA) imaging provides additional diagnostic value in characterizing aortic endoleaks. This protocol describes a qualitative and quantitative approach using time-attenuation curve analysis to characterize endoleaks. The technique of integrating dynamic CTA imaging with fluoroscopy using 2D-3D image fusion is illustrated for better image guidance during treatment.

In the United States, more than 80% of all abdominal aortic aneurysms are treated by endovascular aortic aneurysm repair (EVAR). The endovascular approach ...

Characterizing Different Lesion Types of Laser-Induced CNV in Mouse

Characterization of Vascular Morphology of Neovascular Age-Related Macular Degeneration by Indocyanine Green Angiography

Age-related macular degeneration (AMD) is a leading cause of blindness among older individuals, and its prevalence is rapidly increasing due to the aging population. Choroidal neovascularization (CNV) or wet AMD, which accounts for 10%-20% of all AMD cases, is responsible for an alarming 80%-90% of AMD-related blindness. Current anti-VEGF therapies show suboptimal responses in approximately 50% of patients. Resistance to anti-VEGF treatment in CNV patients is often associated with arteriolar CNV, while responders tend to have capillary CNV. While fluorescein angiography (FA) is commonly used to assess leakage patterns in wet AMD patients and animal models, it does not provide information about CNV vascular morphology (arteriolar CNV vs. capillary CNV). This protocol introduces the use of indocyanine green angiography (ICGA) to characterize lesion types in laser-induced CNV mouse models. This method is crucial for investigating the mechanisms and treatment strategies for anti-VEGF resistance in wet AMD. It is recommended to incorporate ICGA alongside FA for comprehensive assessment of both leakage and vascular features of CNV in mechanistic and therapeutic studies.

Author Spotlight: Overcoming Anti-VEGF Resistance Through Advanced Vascular Morphology Assessment in Choroidal Neovascularization

Currently, fluorescein angiography (FA) is the preferred method for identifying leakage patterns in animal models of choroidal neovascularization (CNV). However, FA does not provide information about vascular morphology. This protocol outlines the use of indocyanine green angiography (ICGA) to characterize different lesion types of laser-induced CNV in mouse models.

Age-related macular degeneration (AMD) is a leading cause of blindness among older individuals, and its prevalence is rapidly increasing due to the aging ...