Real-time in vitro intravascular reconstruction and navigation for endovascular aortic stent grafting

Design consideration on integration of mechanical intravascular ultrasound and electromagnetic tracking sensor for intravascular reconstruction

PURPOSE

Considering vessel deformation, endovascular navigation requires intraoperative geometric information. Mechanical intravascular ultrasound (IVUS) with an electromagnetic (EM) sensor can be used to reconstruct blood vessels with thin diameter. However, the integration design should be evaluated based on the factors affecting the reconstruction error.

METHODS

The interference between the mechanical IVUS and EM sensor was measured in different relative positions. Two designs of the integrated catheter were evaluated by measuring the reconstruction errors using a rigid vascular phantom.

RESULTS

When the distance from the EM sensor to the field generator was 75 mm, the interference from mechanical IVUS to an EM sensor was negligible, with position and rotation errors less than 0.1 mm and 0.6°, respectively. The reconstructed vessel model for proximal IVUS transducer had a smooth surface but an inaccurate shape at large curvature of the vascular phantom. When the distance to the field generator was 175 mm, the error increased significantly.

CONCLUSION

Placing the IVUS transducer on the proximal side of the EM sensor is superior in terms of interference reduction but inferior in terms of mechanical stability compared to a distal transducer. The distal side is preferred due to better mechanical stability during catheter manipulation at larger curvature. With this configuration, surface reconstruction errors less than 1.7 mm (with RMS 0.57 mm) were achieved when the distance to the field generator was less than 175 mm.

New tools to reduce radiation exposure during aortic endovascular procedures

INTRODUCTION

The evolution of endovascular surgery over the past 30 years has made it possible to treat increasingly complex vascular pathologies with an endovascular method. Although this generally speeds up the patient's recovery, the risks of health problems caused by long-term exposure to radioactive radiation increase. This warrants the demand for radiation-reducing tools to reduce radiation exposure during these procedures.

AREAS COVERED

For this systematic review Pubmed, Embase and Cochrane library databases were searched on 28 December 2021 to provide an overview of tools that are currently used or have the potential to contribute to reducing radiation exposure during endovascular aortic procedures. In addition, an overview is presented of radiation characteristics of clinical studies comparing a (potential) radiation-reducing device with conventional fluoroscopy use.

EXPERT OPINION

Radiation-reducing instruments such as fiber optic shape sensing or electromagnetic tracking devices offer the possibility to further reduce or even eliminate the use of radiation during endovascular procedures. In an era of increasing endovascular interventional complexity and awareness of the health risks of long-term radiation exposure, the use of these technologies could have a major impact on an ongoing challenge to move toward radiation-free endovascular surgery.

Visual-electromagnetic system: A novel fusion-based monocular localization, reconstruction, and measurement for flexible ureteroscopy

BACKGROUND

During flexible ureteroscopy (FURS), surgeons may lose orientation due to intrarenal structural similarities and complex shape of the pyelocaliceal cavity. Decision-making required after initially misjudging stone size will also increase the operative time and risk of severe complications.

METHODS

A intraoperative navigation system based on electromagnetic tracking (EMT) and simultaneous localization and mapping (SLAM) was proposed to track the tip of the ureteroscope and reconstruct a dense intrarenal three-dimensional (3D) map. Furthermore, the contour lines of stones were segmented to measure the size.

RESULTS

Our system was evaluated on a kidney phantom, achieving an absolute trajectory accuracy root mean square error (RMSE) of 0.6 mm. The median error of the longitudinal and transversal measurements was 0.061 and 0.074 mm, respectively. The in vivo experiment also demonstrated the effectiveness.

CONCLUSION

The proposed system worked effectively in tracking and measurement. Further, this system can be extended to other surgical applications involving cavities, branches and intelligent robotic surgery.

An automatic skill evaluation framework for robotic surgery training

BACKGROUND

To provide feedback to surgeons in robotic surgery training, many surgical skill evaluation methods have been developed. However, they hardly focus on the performance of the surgical motion segments. This paper proposes a method of specifying a trainee's skill weakness in the surgical training.

METHODS

This paper proposed an automatic skill evaluation framework by comparing the trainees' operations with the template operation in each surgical motion segment, which is mainly based on dynamic time warping (DTW) and continuous hidden Markov model (CHMM).

RESULTS

The feasibility of this proposed framework has been preliminarily verified. For specifying the skill weakness in instrument handling and efficiency, the result of this proposed framework was significantly correlated with that of manual scoring.

CONCLUSION

The automatic skill evaluation framework has shown its superiority in efficiency, objectivity, and being targeted, which can be used in robotic surgery training.

AN INTERACTIVE VIRTUAL INTRACORONARY STENTING SYSTEM BASED ON INTRAVASCULAR ULTRASOUND

Percutaneous transluminal coronary angioplasty (PTCA) is a minimally invasive surgery in the clinical treatment of coronary artery diseases. The successful operation highly depends on the size and accurate placement of the stent. In this study, a virtual stenting (VS) system was designed and implemented to facilitate the planning of PTCA. A three-dimensional (3D) vessel model was reconstructed through fusing intravascular ultrasound (IVUS) sequential images and simultaneously recorded X-ray angiograms during cardiac intervention. The user is allowed to intuitively explore the vessel in an endoscopic manner by creating/updating a fly-through trajectory in the lumen. A virtual stent library including a better variety of commercially available bare metal heart stents was built. The user is allowed to select a proper stent according to the morphology of the vessel and lesion and to move it to the lesion. Also, the user can visually observe the stent expansion/apposition and flexibly adjust its position. The system is used to assist visual diagnosis of the vascular diseases, evaluation of interventional treatment and training of the medical personnel.

A Review on Real-Time 3D Ultrasound Imaging Technology

Real-time three-dimensional (3D) ultrasound (US) has attracted much more attention in medical researches because it provides interactive feedback to help clinicians acquire high-quality images as well as timely spatial information of the scanned area and hence is necessary in intraoperative ultrasound examinations. Plenty of publications have been declared to complete the real-time or near real-time visualization of 3D ultrasound using volumetric probes or the routinely used two-dimensional (2D) probes. So far, a review on how to design an interactive system with appropriate processing algorithms remains missing, resulting in the lack of systematic understanding of the relevant technology. In this article, previous and the latest work on designing a real-time or near real-time 3D ultrasound imaging system are reviewed. Specifically, the data acquisition techniques, reconstruction algorithms, volume rendering methods, and clinical applications are presented. Moreover, the advantages and disadvantages of state-of-the-art approaches are discussed in detail.