Vessel-based Ultrasound Registration

Study Overview
=================
Brief Summary
-----------------
In this study we aim to develop an automatic pelvic artery segmentation algorithm, which is required for future clinical implementation of US registration for surgical navigation. Various registration methods will be evaluated with the data of this study to obtain most optimal results. If automatic segmentation and registration is successful, the final accuracy of the developed US registration method for tumor tracking should be evaluated in future studies in patients eligible for surgical navigation. Eventually, we aim to replace the CBCT-scan with an automatic tracked US registration pipeline for a more efficient and accurate registration procedure, which could improve the applicability and accuracy of surgical navigation and patient outcomes.

Detailed Description
-----------------
Image-guided navigation surgery allows for full utilization of pre-operative imaging during surgery and has the potential of reducing both irradical resections and morbidity. To use navigation, a registration procedure is required to correlate pre-operative imaging with the patient's position on the operating room (OR). Currently, registration is done by Cone-Beam CT (CBCT) scanning on the OR prior to navigation surgery. However, the main limitation of the CBCT method is that it cannot compensate for per-operative changes such as bed rotation, retractor placement and tissue displacement due to the surgery. Alternatively, by using intra-operative tracked ultrasound and vessel-based patient registration, changing conditions during surgery can better be dealt with. This improved patient registration method could lead to an increased navigation accuracy and improved clinical usability and outcomes. The main difference between CBCT and proposed ultrasound registration is that CBCT is based on bones, while the ultrasound is based on vessels. Bones can be very easily imaged on the CBCT and therefore used for bone-bone registration with pre-operative CT-scans. However, vessels are more difficult to acquire, especially with ultrasound, and an automatic registration process with pre-operative imaging is needed for efficient clinical usability. For this, the vessels need to be extracted from the tracked ultrasound images to create a 3D representation that can be registered. Therefore, an algorithm needs to be developed that can automatically segment the pelvic vessels from ultrasound images.

Official Title
-----------------
Intra-operative Pelvic Vessel Acquisition, Towards Ultrasound Registration for Surgical Navigation

Conditions
-----------------
Abdominal Cancer

Intervention / Treatment
-----------------
* Procedure: Intra-operative ultrasound measurement


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: ≥ 18 years old Scheduled for laparotomy A clinical pre-operative abdominal CT scan is available Patient provides written informed consent Exclusion Criteria: Metal implants in the pelvic area which could influence the 3D modelling or tracking accuracy Patients with a pacemaker or defibrillator Patient received pelvic-abdominal treatment, e.g. surgery or radiotherapy, between the pre-operative CT scan and laparotomy, which might altered the patient's anatomy

Ages Eligible for Study
-----------------
Minimum Age: 18 Years

Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
No

Study Plan
=================
How is the study designed?
-----------------

Design Details

Primary Purpose: Other
Intervention Model: Single Group Assignment
Interventional Model Description: One group to evaluate the feasibility and accuracy of the proposed methods.
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Patients scheduled for laparotomy<br>This is a single-center observational feasibility study to develop an automatic segmentation and registration algorithm based on ultrasound imaging of the pelvic arteries. The duration of this study will be approximately 1 year. Patients scheduled for a laparotomy at the NKI are eligible for inclusion. Patients are informed about the study before the planned surgery and, after being provided with the necessary information regarding participation in the study, will be asked for informed consent. The ultrasound acquisitions for this study will be performed intra-operatively with CE marked equipment for intra-operative ultrasound. There is no impact on the standard surgical procedure or decision making of the surgery. After surgery, no further participation or cooperation of the patient is required. | Procedure: Intra-operative ultrasound measurement<br>* A patient-specific 3D model will be created using an available pre-operative CT scan. Anatomical target points are selected on this virtual model before the start of the surgery. Prior to surgery, a patient-reference electromagnetic (EM) sensor will be placed between the patient and the matrass on the operating table to account for patient movement during acquisition. Intra-operatively, an initial point registration of the 3D model with the electromagnetic tracking system (EMTS) will be performed based on ultrasound (US) imaging of the arterial bifurcations by the surgeon. Then, the surgeon will acquire multiple US sweeps of the pelvic arteries (abdominal aorta and left and right iliac arteries). For validation purposes, the pre-operatively defined anatomical target points will be visualized on US imaging and by pinpointing the EM tracked pointer. All tracking and US data will be recorded and stored for post-operative analysis.<br>|

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Accuracy of developed automatic segmentation algorithm | An automatic segmentation algorithm for real-time intra-operative pelvic vessel segmentation from tracked US images will be developed. The accuracy of this network will be evaluated using the Dice similarity coefficient, ranging from 0 to 1 where a higher score means a better outcome. | One day | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Accuracy of intra-operative ultrasound registration | To evaluate the accuracy of different patient registration methods of intra-operative US imaging with pre-operative CT imaging, such as 3D model or centerline registration. | One day | 
| Usability of intra-operative ultrasound registration | Evaluation of the intraoperative usability of the tracked US device and visualization of pelvic vessels by the surgeons will be evaluated using the system usability scale (SUS). This scale ranges from 0-100 where a higher score means a better outcome. | One day | 

 Terms related to the study
=================
Keywords Provided by Centre Hospitalier Valida
-----------------
Surgical Navigation, Ultrasound, Registration, Electromagnetic Tracking, Pelvic Malignancies, Deep Learning, Segmentation