Proposedmethod

Proposedmethod

Conclusions• Novel approach to track the aortic valve calcifications in fluoroscopy imaging. [Gretsi 2015]• Minimal user-interaction is required to initialize the algorithm.• Could be used to track the aortic valve plane that represents the moving target for THV

deployment, in order to limit the use of contrast agent. [EMBC 2013]• Could be applied also for the tracking of other structures of interest. [SURGETICA 2014]

Perspectives• Multi-tracking of calcifications and/or devices to improve the robustness of the approach.

ExperimentalResults

Objective: tracking of aortic valve calcifications in intra-operative fluoroscopic images.Difficulties: size and density of calcifications.

ExperimentalResults

Tracking errors reported from 10 sequences

Qualitative result and Displacement magnitude of the sample sequence 02

• Average detection rate greater than 88%.• Tracking error less than 1.0mm for

93.3% of the tracked frames.• Average processing time less than 30ms

for each frame.

Based on an adaptive detection scheme, the tracking process consists in:• Finding new patches that correspond to the initial calcification patch.• Learning of appearance changes of the target calcification.

To provide additional landmarks to guide THV navigation inside the moving aortic root.

Endovascular repairTranscatheter aortic valve

implantation (TAVI)Aortic valve stenosis

(AVS)

TranscatheterHeartValve

(THV)

Endovascular aneurysm repair (EVAR)

Aortic abdominal aneurysm(AAA)

X-ray angiographic / fluoroscopic guidance

- Catheterizationunder2DX-rayguidance.- Vasculaturesarevisibleonlyinstantlywithcontrastproductinjection.- Intra-operativepositioninganddeploymenthavetobeperformedatthesiteplannedfromthepre-operativeCT.

Catheter

Renal artery

Catheter

Motivation: to limit the use of X-rays and contrast agent in the course of endovascular interventions.Objectives: to reconsider/improve the tracking of endovascular devices and / or vasculatures (augmented perception)

Conclusions• RANSAC-based fiducially-free 3D-3D registration for electromagnetic navigation.• Without Intra-operative X-ray Imaging, without fiducial landmark. [SURGETICA 2014]• Phantom study: precision of 1.4mm.

Perspectives• Additional experiments, especially in-vivo experiments are required.

Electromagnetic tracking system (EMTS) could be used to locate devices through tissues.The first issue: Matching of the 3D EMT and the 3D patient coordinate systems.

Anatomy of the aorta

Aortic valve stenosis (AVS)

• Narrowing of the aortic valve opening• Calcified aortic valve leaflets

Pathologies

Aortic stenosis/Aortic aneurysm

Abdominal aortic aneurysm (AAA)

Localized rupture of the parallelism of the aortic walls

For example:

Using of the tracked trajectories of the magnetic sensor inside the vasculature[de Lambert A, Esneault S, Lucas A, Haigron P, Cinquin Ph, Magne J-L, European journal of vascular and endovascular surgery, 2012]

3D-3D registration

Analysis of different distance criteria between the electromagnetic trajectory and the 3D description of the patient vasculature.

Entire lumen Centerlines Minimum BendingEnergy Path (minBEP)

Reduced lumen

non constraint / constraint Potential location of the EM trajectory within the lumen

Intra-operative3D electromagnetic

Trajectory (ET)

Pre-operative CT3D description

of the patient vasculature (VL)

R - 3D Rotation / T - 3D Translation!" - acceptance functiondist – Point to vasculature description distance.

#∗ %,̇ )̇ = argmin1,2

3456(89 :)1,2, ;<), ;<

The EM outliers compared to the 3D vasculature description are managed by a robust framework (RANdom SAmple Consensus).

!

Trackingofaorticvalvecalcifications

Pre-operative3DModels

+3D/2DStaticRegistration

Intra-operative2DLandmarks

Dynamicoverlayof2DlandmarksLiveFluoroscopicImages Dynamicoverlayof3Dmodels

LongHungNGUYEN-DUCduclonghung.nguyen@gmail.com

INSERM, U1099, Rennes, F-35000 FranceUniversité de Rennes 1, LTSI, Rennes, F-35000 France

Trackingofstructuresfortheendovasculartreatmentofaorticpathologies

ContextandObjectives

Electromagnetictrackingofendovasculardevices Image-basedtrackingofmovingvasculatures

Positions/3D description

P1 P2 P3 P4 Mean Stdev

Entire lumen 1.825 1.801 1.576 2.627 1.957 0.433

Reduced lumen 1.720 0.887 0.897 2.205 1.427 0.211

Centerlines 1.596 1.313 0.677 2.080 1.416 0.285

minBEP 2.646 1.849 2.212 3.816 2.631 0.854

Registration and navigation interfaces implemented with CamiTK [C. Fouard et al., 2012]

- For each 3D vasculature description, the registration procedure was repeated 9 times.- Errors are reported from 4 different positions.- Error measurement by exploiting the CBCT.

Target Registration Errors

Constrained EM trajectory

Positions/3D description

P1 P2 P3 P4 Mean Stdev

Entire lumen 3.456 3.134 2.205 3.389 3.046 0.578

Reduced lumen 3.147 2.979 2.125 3.019 2.817 0.467

Centerlines 2.984 2.761 1.924 2.777 2.612 0.470

minBEP 2.653 2.796 1.695 2.527 2.417 0.494

Non constrained EM trajectory