The authors would like to thank the Ulm University Center for Translational Imaging MoMAN for its support.

The study protocol is in compliance with the ethical guidelines of the 1975 Declaration of Helsinki as reflected in a priori approval by the institution&#39;s ethics committee. Written informed consent was obtained from all individual participants included in the study (CSI-Ulm, clinicaltrials.gov NCT02162069).
1. CT Examination
<ol>
	<li>Perform cardiac CT angiography with retrospective ECG-gating using 80 mL of iodinated contrast media injected at a flow rate of 4.0 mL/s followed ...

<ol>
	<li>S&#225;nchez, 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=Navigational+Guidance+and+Ablation+Planning+Tools+for+Interventional+Radiology.">Navigational Guidance and Ablation Planning Tools for Interventional Radiology.</a> Current Problems in Diagnostic Radiology. 32 (2), 225-233 (2017).</li><li>Schwein, A., 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=Feasibility+of+three-dimensional+magnetic+resonance+angiography-fluoroscopy+image+fusion+technique+in+guiding+complex+endovascular+aortic+procedures+in+patients+with+renal+insufficiency.">Feasibility of three-dimensional magnetic resonance angiography-fluoroscopy image fusion technique in guiding complex endovascular aortic procedures in patients with renal insufficiency.</a> Journal of Vascular Surgery. 65 (5), 1440-1452 (2017).</li><li>Ierardi, A. 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J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+quantitative+analysis+of+3-D+coronary+modeling+from+two+or+more+projection+images.">A quantitative analysis of 3-D coronary modeling from two or more projection images.</a> IEEE Transactions on Medical Imaging. 23 (12), 1517-1531 (2004).</li><li>Vernikouskaya, I., 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=Image-guidance+for+transcatheter+aortic+valve+implantation+(TAVI)+and+cerebral+embolic+protection.">Image-guidance for transcatheter aortic valve implantation (TAVI) and cerebral embolic protection.</a> International Journal of Cardiology. 249, 90-95 (2017).</li><li>Ramlawi, B., Anaya-Ayala, J. E., Reardon, M. 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On behalf of all authors, the corresponding authors state that there are no relationships that could be construed as a conflict of interest.

The main focus of this study was to investigate the feasibility of IF without modifying the clinically established TAVI workflow. Whereas the gold standard for the co-registration of the pre-interventional CTA data and XR fluoroscopy uses dedicated aortograms8, we propose using multiple approximate registrations with on-the-fly refinements to provide accurate 3D model overlay during the entire course of the intervention.
The continuous manual registration refinement req...

Image fusion (IF) is the process of superimposing datasets acquired at the different time- and viewpoints on different modalities into a single-frame of reference1. XR is the most frequently used imaging modality for intervention guidance. Even though, providing high temporal and spatial resolution, XR has low dimensionality (2D projections) and lacks anatomical details. 3D organ shape models derived from e.g. high-quality pre-interventional CTA data superimposed onto the live fluoroscopy image can augment XR by relevant anatomic soft-tissue structures. Prerequisite step for IF is the co-registration of the different imaging modalities.
Typically, co-registration of preoperative 3D image datasets with XR fluoroscopy involves one of the following techniques2: a) image-based 3D-3D registration of the preoperative 3D dataset with an intraoperative non-/contrast-enhanced CBCT dataset3,4,5,6, or b) direct image-based 2D-3D registration, where two angiographic images with a minimum of 30&#176; angular spacing7,8 are used for co-registration.
With the recent introduction of fusion packages on commercial XR systems, IF can be made more readily available for a wide range of applications. Using those systems, we have previously shown that it is technically feasible and safe to overlay an aortic root model by means of direct image-based 2D-3D registration for supporting transfemoral transcatheter aortic valve implantation (TAVI)8. Without compromising the overall CA or XR dose, IF proved itself highly valuable during TAVI procedure by adding 3D anatomical details to the conventional XR fluoroscopy image, especially during deployment of the cerebral protection device. However, the additional acquisition of the aortograms used for the co-registration required additional CA and XR dose. Therefore, an optimized workflow providing accurate IF without the need of any additional aortograms was highly desirable.
Here, we present an approach to improved co-registration of pre-interventional CTA with real-time XR without requiring any additional CA or C-arm CT scans for IF. The femoral access TAVI is performed as described elsewhere9,10,11. Briefly, both femoral arteries are accessed: one for the guidance of the contralateral puncture, followed by placement of a pigtail catheter through a 6F sheath to allow arteriography during placement of the valve prosthesis; the second for placement of the valve delivery system and subsequent balloon valvuloplasty and device placement. Angiographic confirmation of appropriate puncture is performed in our institution as a standard of care for localization of the puncture height (above the femoral bifurcation) and estimation of the position of the covered stent in case of access-related complications12. For capturing embolic debris, a double-filter cerebral protection system is introduced after insertion of the TAVI delivery sheath prior to the passage of the aortic arch with any further device.
We use arteriograms performed routinely during the puncture of the femoral arteries to establish the initial co-registration. On-the-fly refinement of the co-registration is subsequently performed during the on-going procedure using the position of the pigtail catheter within the aortic root, the double-filter cerebral embolic protection system in the supraaortal vessels and the aortograms performed before the implantation of the valve prosthesis, thus ensuring accurate model overlay at any time point during the intervention.

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	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:247px;">Philips Allura FD10&#160;&#160;</td>
			<td style="width:149px;">Philips Healthcare</td>
			<td style="width:136px;"></td>
			<td style="width:201px;">x-ray system</td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:247px;">EP Navigator Release 5.2.10</td>
			<td style="width:149px;">Philips Healthcare</td>
			<td style="width:136px;"></td>
			<td style="width:201px;">image segmentation and fusion SW</td>
		</tr>
		<tr height="39">
			<td height="39" style="height:39px;width:247px;">Iomeron 350</td>
			<td style="width:149px;">Bracco Imaging Deutschland GmbH</td>
			<td style="width:136px;"></td>
			<td>x-ray contrast agent</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:41px;width:247px;">Sentinel&#160; double-filter cerebral protection system</td>
			<td style="width:149px;">Claret Medical, Inc.</td>
			<td style="width:136px;"></td>
			<td style="width:201px;">double-filter cerebral protection system&#160;</td>
		</tr>
		<tr height="27">
			<td height="27" style="height:27px;width:247px;">Matlab R2013</td>
			<td style="width:149px;">MathWorks</td>
			<td style="width:136px;"></td>
			<td>statistical analysis</td>
		</tr>
	</tbody>
</table>

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.

We introduced a novel co-registration approach for image fusion during TAVI, which allows overlaying the patient-specific anatomic model onto the live XR images during the entire TAVI procedure without the need for any additional aortograms.
Several interventional steps will benefit from the IF: (1) guidance of the puncture of the common femoral artery above the femoral bifurcation on the sheath side (Figure...

Watch this Scientific Journal Video about Improved Registration of 3D CT Angiography with X-ray Fluoroscopy for Image Fusion During Transcatheter Aortic Valve Implantation at JoVE.com

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

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 ...

This method can help answer key questions in the field of inter-procedural image-based guidance, about the limited anatomical information available from x-ray fluoroscopy, with respect to a patient's 3D anatomy. The main advantage of this technique is that it represents a further incremental advancement in real-time navigation of complex interventions that will ultimately lead to increased efficacy and safety of the procedures. The number of TAVR procedures is continuously increasing in Germany, and with that, in some cases, the complexity is also very high.To treat those patients properly, we do need image solution, especially in the field of cerebral embolic protection. Although this procedure has been demonstrated for a specific system, it can easily be transferred to other systems as long as a similar software is available. To segment the computer tomography, or CT, aorta and left ventricle images, drag the CT data into the patient's view within the image fusion software and deselect the other tissues until only the aorta and left ventricle remain.Verify that the edges of the tissues are correctly detected in each slice, using the edit button to modify the automatic segmentation in the tissue window as necessary. To perform manual segmentation of any additional structures, click Add and use the editing tools to fill the structure, drag the edges of the structure in the 2D view, or remove structure parts in the 3D view. Then perform manual segmentation of the main trunks of the left and right coronary arteries, main artery branches, left and right iliofemoral arteries, hip bones, and hip joints as just demonstrated.After merging the selected patient's data with the current patient's data in the x-ray system, place three reference markers at the aortic valve cusps in the Live Work setting by clicking Add New Tack Point in the Tack Points window. Next, open the Registration Workstep to acquire the x-ray runs. Click Copy to Reference View 1 to copy the angiographic projection of the appropriate puncture, and approximately 20-30 degrees in the left anterior oblique orientation, or approximately 20-30 degrees in the right anterior oblique orientation, depending on the initial puncture side, into the Reference View 1.Click Copy to Reference View 2 to copy the x-ray projection acquired in approximately the anterior/posterior orientation during visualization of the transition from the contralateral a. iliaca communis to the a. femoralis communis into Reference View 2.Use the Registration Pan, Registration Rotate, and Registration Roll interaction tools to manually align the model of the iliofemoral arteries with the acquired x-ray projections. Use the initial course co-registration to guide the puncture of the common femoral artery on the sheath side, and click Copy to Reference View to record an angiographic projection of the device sheath femoral artery in the right anterior oblique 20-30 degree orientation. Then finalize the image co-registration in the iliofemoral region.To use these data for further overlay realignment, copy any additional acquired projections to the reference view during the transition from the iliofemoral to the thoracic region, as well as any catheterization of the brachiocephalic trunk via the right radial artery. After placing the pigtail catheter into the aortic arch, acquire two fluoroscopic projections without a contrast agent in the left anterior oblique 30-40 degree and right anterior oblique 20-30 degree orientations, and copy the projections into Reference Views 1 and 2 as demonstrated. Use the interaction tools to manually adjust the registration in the thoracic region, and guide the placement of the protection device based entirely on the anatomic overlay.Then use the interaction tools to manually correct the overlay position on each acquired x-ray projection over the entire course of the intervention as necessary to ensure an accurate overlay at each time point, using the positions of the pigtail catheter, the double filter cerebral embolic protection system, and the aortogram as landmarks. Technical difficulties can arise from the static nature of the anatomic models, caused by overlay misalignment in instances of cardiac and respiratory motion, the formation of the structures during device manipulation, or inconsistent patient positioning between the settee and catheterization tables. Several interventional steps will benefit from the image fusion.For example, the guidance of a common femoral artery puncture above the femoral bifurcation on the sheath side, the accurate placement of the cerebral embolic protection device, even in very torturous anatomies, based solely on the anatomic overlay, the visualization of the model in an arbitrary c-arm angulation without x-ray exposure or contrast agent administration, as well as identification of the optimal view before the valve deployment, and the alignment of the valve prosthesis in even very complex anatomies. Once mastered, the manual segmentation of all of the related anatomic structures can be completed in 20-30 minutes, depending on the quality of the CT images. While attempting this procedure, it's important to consider that the more projections that are available for the co-registration, the higher the accuracy of the overlay will be.The demonstrated protocol is applicable to a wide variety of transcatheter interventions, from the clinically established, such as atrial and ventricular ablations, to procedures on the verge of clinical implementations, such as percutaneous treatment of the tricuspid valve.

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10.3K visualizações.  Ulm University Medical Center. This method can help answer key questions in the field of inter-procedural image-based guidance, about the limited anatomical information available from x-ray fluoroscopy, with respect to a patient's 3D anatomy. The main advantage of this technique is that it represents a further incremental advancement in real-time navigation of complex interventions that will ultimately lead to increased efficacy and safety of the procedures. The number of TAVR procedures is continuously increasing in Germa...