  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.
