Tracking of devices and of structures for the endovascular treatment of aortic pathologies
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Transcript of Tracking of devices and of structures for the endovascular treatment of aortic pathologies
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
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