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Endovascular Detection of Catheter-Thrombus Contact by Vacuum Excitation

Jared Lawson, Madison Veliky, Colette P. Abah, Mary S. Dietrich, Rohan Chitale, Nabil Simaan

TL;DR

Problem: reliably detecting when an aspiration catheter tip contacts a thrombus during mechanical thrombectomy to improve first-pass success. Approach: proximal vacuum excitation with inline pressure sensing and a Gaussian-kernel SVM classifier operating on two pressure-based features. Key findings: benchtop validation achieved 99.67% accuracy with robust performance across vessel geometries and heart rates, and a user study showed a significant improvement in detecting clot contact when auditory feedback from the classifier was provided (OR = 2.86, p = 0.031). Significance: the method uses off-the-shelf catheters without distal sensors, offering low-cost intraoperative feedback that can reduce procedure time and cognitive load, potentially improving first-pass effect.

Abstract

Objective: The objective of this work is to introduce and demonstrate the effectiveness of a novel sensing modality for contact detection between an off-the-shelf aspiration catheter and a thrombus. Methods: A custom robotic actuator with a pressure sensor was used to generate an oscillatory vacuum excitation and sense the pressure inside the extracorporeal portion of the catheter. Vacuum pressure profiles and robotic motion data were used to train a support vector machine (SVM) classification model to detect contact between the aspiration catheter tip and a mock thrombus. Validation consisted of benchtop accuracy verification, as well as user study comparison to the current standard of angiographic presentation. Results: Benchtop accuracy of the sensing modality was shown to be 99.67%. The user study demonstrated statistically significant improvement in identifying catheter-thrombus contact compared to the current standard. The odds ratio of successful detection of clot contact was 2.86 (p=0.03) when using the proposed sensory method compared to without it. Conclusion: The results of this work indicate that the proposed sensing modality can offer intraoperative feedback to interventionalists that can improve their ability to detect contact between the distal tip of a catheter and a thrombus. Significance: By offering a relatively low-cost technology that affords off-the-shelf aspiration catheters as clot-detecting sensors, interventionalists can improve the first-pass effect of the mechanical thrombectomy procedure while reducing procedural times and mental burden.

Endovascular Detection of Catheter-Thrombus Contact by Vacuum Excitation

TL;DR

Problem: reliably detecting when an aspiration catheter tip contacts a thrombus during mechanical thrombectomy to improve first-pass success. Approach: proximal vacuum excitation with inline pressure sensing and a Gaussian-kernel SVM classifier operating on two pressure-based features. Key findings: benchtop validation achieved 99.67% accuracy with robust performance across vessel geometries and heart rates, and a user study showed a significant improvement in detecting clot contact when auditory feedback from the classifier was provided (OR = 2.86, p = 0.031). Significance: the method uses off-the-shelf catheters without distal sensors, offering low-cost intraoperative feedback that can reduce procedure time and cognitive load, potentially improving first-pass effect.

Abstract

Objective: The objective of this work is to introduce and demonstrate the effectiveness of a novel sensing modality for contact detection between an off-the-shelf aspiration catheter and a thrombus. Methods: A custom robotic actuator with a pressure sensor was used to generate an oscillatory vacuum excitation and sense the pressure inside the extracorporeal portion of the catheter. Vacuum pressure profiles and robotic motion data were used to train a support vector machine (SVM) classification model to detect contact between the aspiration catheter tip and a mock thrombus. Validation consisted of benchtop accuracy verification, as well as user study comparison to the current standard of angiographic presentation. Results: Benchtop accuracy of the sensing modality was shown to be 99.67%. The user study demonstrated statistically significant improvement in identifying catheter-thrombus contact compared to the current standard. The odds ratio of successful detection of clot contact was 2.86 (p=0.03) when using the proposed sensory method compared to without it. Conclusion: The results of this work indicate that the proposed sensing modality can offer intraoperative feedback to interventionalists that can improve their ability to detect contact between the distal tip of a catheter and a thrombus. Significance: By offering a relatively low-cost technology that affords off-the-shelf aspiration catheters as clot-detecting sensors, interventionalists can improve the first-pass effect of the mechanical thrombectomy procedure while reducing procedural times and mental burden.
Paper Structure (19 sections, 3 equations, 8 figures, 2 tables, 1 algorithm)

This paper contains 19 sections, 3 equations, 8 figures, 2 tables, 1 algorithm.

Table of Contents

  1. Introduction
  2. Clinical Motivation
  3. Relevant Works
  4. Materials and Methods
  5. System Overview
  6. Clinical Workflow of Aspiration Thrombectomy
  7. The Proposed Sensory-Guided Workflow
  8. Vacuum Sensing System Overview
  9. Phantom Models
  10. Detection Algorithm
  11. SVM Training and Validation
  12. Algorithm Implementation
  13. Benchtop Validation of Detection Robustness to Vessel Geometry and Heartbeat
  14. User Study Protocol
  15. Results
  16. ...and 4 more sections

Figures (8)

  • Figure 1: M1 Segment MCA Occlusion Angiogram. (a) is the true digital subtraction angiogram (DSA), while (b) is the roadmap of the DSA used for navigation guidance. radiopaque catheter tip as viewed by the interventionalist, location of halting contrast flow, expert estimated location of the true thrombus location
  • Figure 2: Clinical Workflow for Mechanical Thrombectomy with Aspiration (ADAPT ADAPT2014). The first block (a) represents the starting point of the procedure. Blocks labeled (b) require manual navigation steps of the procedure. (c) blocks indicate where intraoperative imaging is used to visualize the anatomy. The (d) block and dotted lines indicate steps that are introduced with the proposed clinical workflow, which include sensing by vacuum excitation. Dashed lines refer to steps which are in the current workflow, but would not be used during the proposed workflow
  • Figure 3: Sensing System Overview. (a) shows a higher-level image including the control computers, motorized syringe connecting to the aspiration catheter (left 'Catheters' arrow which is inserted in the guide catheter (top 'Catheters' arrow), which is inserted into the phantom model. (b) focuses on the motorized syringe to show the pressure sensor connected to the syringe output.
  • Figure 4: Phantom Models including vessels and mock thrombi. (a) shows an aspiration catheter inserted in a single Tygon tube vessel with a mock thrombus made from TrueClot synthetic clot material. (b) shows the aspiration catheter inserted in a branch of the United Biologics Neuro System Trainer, with a noise putty used for mock thrombus.
  • Figure 5: An example validation of the model using 30% of the data to train and 70% to validate.
  • ...and 3 more figures