List of Papers By topics Author List
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Authors
Sunish Mathews, Richard Caulfield, Callum Little, Malcolm Finlay, Adrien Desjardins
Abstract
Ultrasound imaging is widely used for guiding minimally invasive cardiovascular procedures such as structural heart repair and renal denervation. Visualisation of medical devices such as catheters is critically important and it remains challenging in many clinical contexts. When 2D ultrasound imaging is used, the catheter can readily stray from the imaging plane; with 3D imaging, there can be a loss of visibility at steep angles of insonification. When the catheter tip is not accurately identified, there can be damage to critical structures and procedural inefficiencies. In this paper, we present a tracking system to directly visualise the catheter tip with a custom fibre optic ultrasound sensor integrated into a microcatheter, in concert with an external ultrasound imaging probe. Pairs of co-registered images were acquired in rapid succession: a tracking image obtained from the ultrasonic sensor signals that were time-synchronised to the ultrasound imaging probe transmissions, and a conventional B-mode ultrasound image. The custom fibre-optic sensor comprised a free-standing membrane originally developed for blood pressure sensing, which was optically interrogated with a wavelength-tuneable laser for ultrasound reception. The measured axial and lateral tracking accuracies in water were both within the range of 0.2 to 1 mm. To obtain a preliminary indication of the clinical potential of this ultrasonic catheter tracking system, insertions of the catheter was delivered over a guidewire into the femoral and renal arteries in an in vivo porcine model and intravascular blood pressure waveforms were obtained concurrently. The results demonstrate that ultrasonic catheter tracking using optically-interrogated fibre optic blood pressure sensors is viable, and that it could be useful to guide minimally invasive cardiovascular procedures by providing accurate, real-time visualisation of the catheter tip.
Link to paper
DOI: https://doi.org/10.1007/978-3-031-43996-4_60
SharedIt: https://rdcu.be/dnwP4
Link to the code repository
N/A
Link to the dataset(s)
N/A
Reviews
Review #1
- Please describe the contribution of the paper
The paper finishes ultrasonic catheter tracking using optically-interrogated fiber optic blood pressure sensors, and will potentially enable ultrasound imaging to be used in place of X-ray imaging for guidance. The measured axial and lateral tracking accuracies in water were both within the range of 0.2 to 1 mm.
- Please list the main strengths of the paper; you should write about a novel formulation, an original way to use data, demonstration of clinical feasibility, a novel application, a particularly strong evaluation, or anything else that is a strong aspect of this work. Please provide details, for instance, if a method is novel, explain what aspect is novel and why this is interesting.
This paper presents a tracking system to directly visualize a custom fiber optic ultrasound sensor integrated into a rapid-exchange microcatheter, in the coordinate system of an external ultrasound imaging probe. The main strength of the paper is a new tracking system of rapid-exchange microcatheter.
- Please list the main weaknesses of the paper. Please provide details, for instance, if you think a method is not novel, explain why and provide a reference to prior work.
This paper finished the experiments on in vivo porcine model. However, the experimental scene and experimental results of in vivo situation are limited. In addition, weather the proposed tracking method is suitable for various ultrasound probe.
- Please rate the clarity and organization of this paper
Good
- Please comment on the reproducibility of the paper. Note, that authors have filled out a reproducibility checklist upon submission. Please be aware that authors are not required to meet all criteria on the checklist - for instance, providing code and data is a plus, but not a requirement for acceptance
The reproducibility of the paper is ok.
- Please provide detailed and constructive comments for the authors. Please also refer to our Reviewer’s guide on what makes a good review: https://conferences.miccai.org/2023/en/REVIEWER-GUIDELINES.html
(1) This paper finished the experiments on in vivo porcine model. However, the experimental scene and experimental results of in vivo situation are limited. (2) About the tracking of rapid-exchange microcatheter, the dynamic characteristics are very important. Especially in the cardiovascular interventions, the microcatheter moves within the vessels. Thus, the experimental results for dynamic microcatheter are very important. (3) Weather the proposed tracking method is suitable for various ultrasound probe? For example, the linear probe and the curve probe. (4) The author said” A digital frequency filter (high-pass; 4 MHz cut-off) was applied for noise rejection and subsequent envelope detection was performed with a Hilbert transform”. Please add more explanation. Because it is important for the final experimental results.
- Rate the paper on a scale of 1-8, 8 being the strongest (8-5: accept; 4-1: reject). Spreading the score helps create a distribution for decision-making
5
- Please justify your recommendation. What were the major factors that led you to your overall score for this paper?
This study is useful and meanningful for endovascular navigation.
- Reviewer confidence
Confident but not absolutely certain
- [Post rebuttal] After reading the author’s rebuttal, state your overall opinion of the paper if it has been changed
N/A
- [Post rebuttal] Please justify your decision
N/A
Review #3
- Please describe the contribution of the paper
In this work, an ultrasound tracking system was developed to achieve accurate instrument identification by using a fiber optic sensor integrated into a rapid exchange microcatheter. Additionally, blood pressure can be measured using the single fiber optic sensor. The experiments on system tracking accuracy in different aspects (axial and lateral direction, and axial orientation) and its preliminary clinical applications were performed and well-demonstrated.
- Please list the main strengths of the paper; you should write about a novel formulation, an original way to use data, demonstration of clinical feasibility, a novel application, a particularly strong evaluation, or anything else that is a strong aspect of this work. Please provide details, for instance, if a method is novel, explain what aspect is novel and why this is interesting.
• This paper is written and organized very well. It is easy to follow. • This work is of high clinical significance, as the newly designed tracking system design not only demonstrated preliminary good performance in microcatheter, but also showed potentials to other instrument tracking cases under ultrasound images.
- Please list the main weaknesses of the paper. Please provide details, for instance, if you think a method is not novel, explain why and provide a reference to prior work.
The SNRs of tracking signals with different microcatheter orientations were calculated in a water tank setting. However, in clinical scenarios, the patient’s soft tissue and structures may have a significant impact on signal attenuation, leading to a potentially lower SNR. It would be valuable to clarify the potential impact of this lower SNR on tracking accuracy in a clinical setting .
- Please rate the clarity and organization of this paper
Very Good
- Please comment on the reproducibility of the paper. Note, that authors have filled out a reproducibility checklist upon submission. Please be aware that authors are not required to meet all criteria on the checklist - for instance, providing code and data is a plus, but not a requirement for acceptance
The details of hardware design and tracking image processing code are not included in this paper. Implementing this system design may not be easy for individuals. However, if the system can be manufactured, it has the potential for high clinical impact.
- Please provide detailed and constructive comments for the authors. Please also refer to our Reviewer’s guide on what makes a good review: https://conferences.miccai.org/2023/en/REVIEWER-GUIDELINES.html
• It would be valuable to clarify how the instrument/sensor position is localized from the ultrasound tracking image. In Figure 3, the single, localized region with “a long tail”, not clear which point should be instrument/sensor location. If this paper picked the top highlight region, it would be valuable to clarify how to ensure its repeatability.? • This paper demonstrated that impacts of different microcatheter orientations on signal-to-noise ratios (SNRs), with both 0 and 180 degrees achieving good SNRs. However, in clinical scenarios, the patient soft tissue and structures may have a significant impact on signal attenuations, leading to potentially low SNRs, It would be valuable to clarify the impact of these factors on tracking accuracy in this setting. • It would be valuable to include a discussion on the reproducibility of this tracking system. Specifically, can this design be consistently replicated for manufacturing in the future?
- Rate the paper on a scale of 1-8, 8 being the strongest (8-5: accept; 4-1: reject). Spreading the score helps create a distribution for decision-making
6
- Please justify your recommendation. What were the major factors that led you to your overall score for this paper?
This CAI work is of high clinical significance, as the newly designed tracking system design not only demonstrated preliminary good performance in microcatheter, but also showed potentials to other instrument tracking cases under ultrasound images.
- Reviewer confidence
Confident but not absolutely certain
- [Post rebuttal] After reading the author’s rebuttal, state your overall opinion of the paper if it has been changed
N/A
- [Post rebuttal] Please justify your decision
N/A
Review #4
- Please describe the contribution of the paper
This paper proposes ultrasonic tracking of a microcatheter that is used for vascular interventions. Tracking uses signal from an ultrasound transducer on the patient near the location of the catheter in a vessel. This method has a potential to reduce or replace X-ray, which is currently used for catheter guidance. Evaluation in an animal model shows great accuracy.
- Please list the main strengths of the paper; you should write about a novel formulation, an original way to use data, demonstration of clinical feasibility, a novel application, a particularly strong evaluation, or anything else that is a strong aspect of this work. Please provide details, for instance, if a method is novel, explain what aspect is novel and why this is interesting.
- Novel idea for microcatheter tracking with significant clinical use potential.
- Solution allows blood pressure monitoring along with position tracking.
- Accuracy is well within the range required by clinical vascular interventions.
- In vivo testing.
- Please list the main weaknesses of the paper. Please provide details, for instance, if you think a method is not novel, explain why and provide a reference to prior work.
- The main contribution of this paper is device design and innovation. Evaluation is technically appropriate, but scientific contributions are limited.
- Please rate the clarity and organization of this paper
Very Good
- Please comment on the reproducibility of the paper. Note, that authors have filled out a reproducibility checklist upon submission. Please be aware that authors are not required to meet all criteria on the checklist - for instance, providing code and data is a plus, but not a requirement for acceptance
The methods in the paper are only reproducible for those who have access to special instrumentation. There are no algorithmic contributions.
- Please provide detailed and constructive comments for the authors. Please also refer to our Reviewer’s guide on what makes a good review: https://conferences.miccai.org/2023/en/REVIEWER-GUIDELINES.html
Limitations would be an important part of the Discussion section, and they are almost entirely missing from your paper. It would be useful for readers to understand what are the conditions that would make the proposed method less reliable or less accurate. While customized microcatheters are hard to obtain by most research labs, similar ultrasound-based tracking may be implemented for different devices and applications. It would be useful to disclose code and test dataset that may allow readers to verify these results and use them in their projects.
- Rate the paper on a scale of 1-8, 8 being the strongest (8-5: accept; 4-1: reject). Spreading the score helps create a distribution for decision-making
6
- Please justify your recommendation. What were the major factors that led you to your overall score for this paper?
Although the paper lacks algorithmic contributions, the clinical impact of ultrasound-based catheter tracking may be very significant. If authors added more data and methodological details on position tracking, then it would be a very valuable publication.
- Reviewer confidence
Confident but not absolutely certain
- [Post rebuttal] After reading the author’s rebuttal, state your overall opinion of the paper if it has been changed
N/A
- [Post rebuttal] Please justify your decision
N/A
Primary Meta-Review
- Please provide your assessment of this work, taking into account all reviews. Summarize the key strengths and weaknesses of the paper and justify your recommendation. In case you deviate from the reviewers’ recommendations, explain in detail the reasons why. In case of an invitation for rebuttal, clarify which points are important to address in the rebuttal.
This paper describes a novel tracking system to visualize a custom fiber optic ultrasound sensor integrated with a microcatheter. The paper has a strong contribution to CAI and could potentially be used for many ultrasound-based procedures. I recommend the acceptance of this paper to MICCAI.
Author Feedback
We are grateful to the reviewers for their constructive and insightful comments and their positive feedback, including:
- ‘This study is useful and meaningful for endovascular navigation’ (Reviewer #1)
- ‘This CAI work is of high clinical significance’ (Reviewer #3)
- ‘…the clinical impact of ultrasound-based catheter tracking may be very significant’ (Reviewer #4).
- ‘The paper has a strong contribution to CAI…’ (Meta-Reviewer #1)
All reviewers and the meta-reviewer ranked this paper first in their stacks.
We address feedback below.
== Reviewer #1
- ‘This paper finished the experiments on in vivo porcine model. However, the experimental scene and experimental results of in vivo situation are limited.’
Response: The limited size of this dataset reflected the nature of this development: a pilot study providing the first demonstration of US tracking of a rapid-exchange microcatheter, and also the first study in which concurrent ultrasound and invasive blood pressure measurements were obtained with a single fiber optic sensor.
- ‘Whether the proposed tracking method is suitable for various ultrasound probe?’
Response: in the final version it will be noted that this method is also applicable to other types of probes (e.g. curvilinear).’
- ‘The author said “A digital frequency filter (high-pass; 4 MHz cut-off) was applied for noise rejection and subsequent envelope detection was performed with a Hilbert transform”. Please add more explanation. Because it is important for the final experimental results.’
Response: it will be noted that a Butterworth filter was used here.
== Reviewer #3
- ‘It would be valuable to clarify how the instrument/sensor position is localized from the ultrasound tracking image. In Figure 3, the single, localized region with “a long tail”, not clear which point should be instrument/sensor location.’
Response: in the final version, it will be pointed out that the high-pass filtering significantly reduces this long tail. After filtering, the sensor position in the tracking image was estimated as the centre-of-mass within a 2D region-of-interest centred on the location with maximum signal intensity.
- ‘However, in clinical scenarios, the patient soft tissue and structures may have a significant impact on signal attenuations, leading to potentially low SNRs, It would be valuable to clarify the impact of these factors on tracking accuracy in this setting.’
Response: in the final version, the impact of signal attenuation (e.g. from adipose tissue) will be mentioned (Discussion).
- ‘It would be valuable to include a discussion on the reproducibility of this tracking system. Specifically, can this design be consistently replicated for manufacturing in the future?’
Response: In the final version it will be mentioned that reproducibility of the sensor and device are important areas of focus for clinical translation.
== Reviewer #4
- ‘Limitations would be an important part of the Discussion section, and they are almost entirely missing from your paper. It would be useful for readers to understand what are the conditions that would make the proposed method less reliable or less accurate.’
Response: in the final version, the Discussion section will be expanded (within tight space constraints) to highlight limitations and challenges: signal attenuation (e.g. from adipose tissue), reflections, and speed-of-sound heterogeneities.
- ‘While customized microcatheters are hard to obtain by most research labs, similar ultrasound-based tracking may be implemented for different devices and applications. It would be useful to disclose code and test dataset that may allow readers to verify these results and use them in their projects.’
Response: details of the algorithms and hardware for the system are provided in ref. [1]; those for fabrication of the fiber optic hydrophone are provided in ref. [9]. The suggestion to provide code and test datasets is a good one that will be considered in future studies.