Carotid Ultrasound Boundary Study (CUBS): Technical considerations on an open multi-center analysis of computerized measurement systems for intima-media thickness measurement on common carotid artery longitudinal B-mode ultrasound scans.

After publishing an in-depth study that analyzed the ability of computerized methods to assist or replace human experts in obtaining carotid intima-media thickness (CIMT) measurements leading to correct therapeutic decisions, here the same consortium joined to present technical outlooks on computerized CIMT measurement systems and provide considerations for the community regarding the development and comparison of these methods, including considerations to encourage the standardization of computerized CIMT measurements and results presentation. A multi-center database of 500 images was collected, upon which three manual segmentations and seven computerized methods were employed to measure the CIMT, including traditional methods based on dynamic programming, deformable models, the first order absolute moment, anisotropic Gaussian derivative filters and deep learning-based image processing approaches based on U-Net convolutional neural networks. An inter- and intra-analyst variability analysis was conducted and segmentation results were analyzed by dividing the database based on carotid morphology, image signal-to-noise ratio, and research center. The computerized methods obtained CIMT absolute bias results that were comparable with studies in literature and they generally were similar and often better than the observed inter- and intra-analyst variability. Several computerized methods showed promising segmentation results, including one deep learning method (CIMT absolute bias = 106 ± 89 µm vs. 160 ± 140 µm intra-analyst variability) and three other traditional image processing methods (CIMT absolute bias = 139 ± 119 µm, 143 ± 118 µm and 139 ± 136 µm). The entire database used has been made publicly available for the community to facilitate future studies and to encourage an open comparison and technical analysis (https://doi.org/10.17632/m7ndn58sv6.1).

Carotid Ultrasound Boundary Study (CUBS): An Open Multicenter Analysis of Computerized Intima-Media Thickness Measurement Systems and Their Clinical Impact.

Common carotid intima-media thickness (CIMT) is a commonly used marker for atherosclerosis and is often computed in carotid ultrasound images. An analysis of different computerized techniques for CIMT measurement and their clinical impacts on the same patient data set is lacking. Here we compared and assessed five computerized CIMT algorithms against three expert analysts' manual measurements on a data set of 1088 patients from two centers. Inter- and intra-observer variability was assessed, and the computerized CIMT values were compared with those manually obtained. The CIMT measurements were used to assess the correlation with clinical parameters, cardiovascular event prediction through a generalized linear model and the Kaplan-Meier hazard ratio. CIMT measurements obtained with a skilled analyst's segmentation and the computerized segmentation were comparable in statistical analyses, suggesting they can be used interchangeably for CIMT quantification and clinical outcome investigation. To facilitate future studies, the entire data set used is made publicly available for the community at http://dx.doi.org/10.17632/fpv535fss7.1.

BIOLUX P-III Passeo-18 Lux All-Comers Registry: 24-Month Results in Below-the-Knee Arteries.

PURPOSE: The BIOLUX P-III registry was initiated to further assess the safety and efficacy of the Passeo-18 Lux drug-coated balloon (DCB) in infrainguinal lesions in a real-world environment and in prespecified risk groups. MATERIALS AND METHODS: BIOLUX P-III is a prospective, global, all-comers registry with patients treated under real-world conditions. We herein report 24-month results of the prespecified subgroup of 151 patients with 185 below-the-knee (BTK) lesions. The primary safety and efficacy endpoints were freedom from major adverse events (a composite of freedom from device and procedure mortality through 30 days, major target limb amputation and clinically driven target lesion revascularization) at 6 months and freedom from clinically driven target lesion revascularization (FfTLR) at 12 months. RESULTS: At baseline, 76.0% of patients had critical limb ischemia and 48.9% of lesions were TASC C or D lesions. Technical success was achieved in 97.8%, and bailout stenting was required in 1.1%. Freedom from major adverse events was 86.2% [95% CI 79.4; 90.8] at 6 months, and FfTLR was 90.9% [95% CI 85.2; 94.4] at 12 months. At 24 months, FfTLR was 90.9% [95% CI 85.2; 94.4], freedom from major amputation was 90.1% [95% CI 83.9, 94.0], and overall survival was 79.2% [70.7, 85.5]. There was a significant clinical improvement (mean Rutherford class improvement of - 2.9 ± 1.9, p < 0.0001) and an improvement in pain (mean improvement on Wong-Baker Faces Pain Scale of - 2.7 ± 2.9, p < 0.0001). CONCLUSIONS: In this real-world DCB registry, 24-month outcomes of Passeo-18 Lux demonstrated safety and efficacy in BTK lesions with high patency rates and sustained clinical improvements at 24 months. TRIAL REGISTRATION: NCT02276313.

Real-World Experience With a Paclitaxel-Coated Balloon in Critical Limb Ischemia: 24-Month Subgroup Outcomes of BIOLUX P-III.

OBJECTIVES: The aim of the BIOLUX P-III (A Prospective, International, Multi-Centre, Post-Market All-Comers Registry to Assess the Clinical Performance of the Passeo-18 Lux Paclitaxel Releasing Balloon Catheter in Infrainguinal Arteries - III) registry was to collect real-world data on the Passeo-18 Lux paclitaxel-coated balloon. BACKGROUND: Critical limb ischemia (CLI) is a severe condition associated with high morbidity and mortality. Prospective data are needed to provide further insights on drug-eluting devices. METHODS: BIOLUX P-III is a prospective, post-market, all-comers registry assessing the safety and performance of the Passeo-18 Lux. Clinical information was collected at 6, 12, and 24 months. The authors report 24-month outcomes of the CLI subgroup with patients in Rutherford classes 4 to 6. RESULTS: The CLI subgroup included 328 patients with 422 lesions. Patients were 71.1 ± 10.5 years of age, and 61.0% had diabetes. Femoropopliteal lesions were present in 53.8% (n = 227), below-the-knee lesions were present in 27.0% (n = 114), and lesions were moderate or heavily calcified in 45.0% (n = 190). Major adverse events, defined as 30-day device- or procedure-related mortality, major target limb amputation, and clinically driven target lesion revascularization, occurred in 9.8% of patients through 6 months, in 14.9% through 12 months, and in 19.4% through 24 months. Clinically driven target lesion revascularization occurred in 4.4%, 8.5%, and 12.1%, major amputation in 4.9%, 5.2%, and 6.1%, and mortality in 8.1%, 11.1%, and 20.1%, respectively. Predictors of mortality were age ≥75 years and higher Trans-Atlantic Inter-Society Consensus Document on Management of Peripheral Arterial Disease class, and higher Rutherford class was associated with increased mortality and amputation rates. CONCLUSIONS: In a large, multimorbid patient population with complex lesions and CLI, the safety and performance of the Passeo-18 Lux paclitaxel-coated balloon has been confirmed, with low rates of major amputation and target lesion revascularization.

Biologically Inspired Catheter for Endovascular Sensing and Navigation.

Minimally invasive treatment of vascular disease demands dynamic navigation through complex blood vessel pathways and accurate placement of an interventional device, which has resulted in increased reliance on fluoroscopic guidance and commensurate radiation exposure to the patient and staff. Here we introduce a guidance system inspired by electric fish that incorporates measurements from a newly designed electrogenic sensory catheter with preoperative imaging to provide continuous feedback to guide vascular procedures without additional contrast injection, radiation, image registration, or external tracking. Electrodes near the catheter tip simultaneously create a weak electric field and measure the impedance, which changes with the internal geometry of the vessel as the catheter advances through the vasculature. The impedance time series is then mapped to a preoperative vessel model to determine the relative position of the catheter within the vessel tree. We present navigation in a synthetic vessel tree based on our mapping technique. Experiments in a porcine model demonstrated the sensor's ability to detect cross-sectional area variation in vivo. These initial results demonstrate the capability and potential of this novel bioimpedance-based navigation technology as a non-fluoroscopic technique to augment existing imaging methods.

Online tracking of interventional devices for endovascular aortic repair.

PURPOSE: The continuous integration of innovative imaging modalities into conventional vascular surgery rooms has led to an urgent need for computer assistance solutions that support the smooth integration of imaging within the surgical workflow. In particular, endovascular interventions performed under 2D fluoroscopic or angiographic imaging only, require reliable and fast navigation support for complex treatment procedures such as endovascular aortic repair. Despite the vast variety of image-based guide wire and catheter tracking methods, an adoption of these for detecting and tracking the stent graft delivery device is not possible due to its special geometry and intensity appearance. METHODS: In this paper, we present, for the first time, the automatic detection and tracking of the stent graft delivery device in 2D fluoroscopic sequences on the fly. The proposed approach is based on the robust principal component analysis and extends the conventional batch processing towards an online tracking system that is able to detect and track medical devices on the fly. RESULTS: The proposed method has been tested on interventional sequences of four different clinical cases. In the lack of publicly available ground truth data, we have further initiated a crowd sourcing strategy that has resulted in 200 annotations by unexperienced users, 120 of which were used to establish a ground truth dataset for quantitatively evaluating our algorithm. In addition, we have performed a user study amongst our clinical partners for qualitative evaluation of the results. CONCLUSIONS: Although we calculated an average error in the range of nine pixels, the fact that our tracking method functions on the fly and is able to detect stent grafts in all unfolding stages without fine-tuning of parameters has convinced our clinical partners and they all agreed on the very high clinical relevance of our method.

Desired-View--controlled positioning of angiographic C-arms.

We present the idea of a user interface concept, which resolves the challenges involved in the control of angiographic C-arms for their constant repositioning during interventions by either the surgeons or the surgical staff. Our aim is to shift the paradigm of interventional image acquisition workflow from the traditional control device interfaces to 'desired-view' control. This allows the physicians to only communicate the desired outcome of imaging, based on simulated X-rays from pre-operative CT or CTA data, while the system takes care of computing the positioning of the imaging device relative to the patient's anatomy through inverse kinematics and CT to patient registration. Together with our clinical partners, we evaluate the new technique using 5 patient CTA and their corresponding intraoperative X-ray angiography datasets.

3D stent recovery from one X-ray projection.

In the current clinical workflow of endovascular abdominal aortic repairs (EVAR) a stent graft is inserted into the aneurysmatic aorta under 2D angiographic imaging. Due to the missing depth information in the X-ray visualization, it is highly difficult in particular for junior physicians to place the stent graft in the preoperatively defined position within the aorta. Therefore, advanced 3D visualization of stent grafts is highly required. In this paper, we present a novel algorithm to automatically match a 3D model of the stent graft to an intraoperative 2D image showing the device. By automatic preprocessing and a global-to-local registration approach, we are able to abandon user interaction and still meet the desired robustness. The complexity of our registration scheme is reduced by a semi-simultaneous optimization strategy incorporating constraints that correspond to the geometric model of the stent graft. Via experiments on synthetic, phantom, and real interventional data, we are able to show that the presented method matches the stent graft model to the 2D image data with good accuracy.

Estimating radiation exposure in interventional environments.

In the last decade the use of interventional X-ray imaging, especially for fluoroscopy-guided procedures, has increased dramatically. Due to this the radiation exposure of the medical staff has also increased. Although radiation protection measures such as lead vests are used there are still unprotected regions, most notably the hands and the head. Over time these regions can receive significant amounts of radiation. In this paper we propose a system for approximating the radiation exposure of a physician during surgery. The goal is to sensibilize physicians to their radiation exposure and to give them a tool to quickly check it. To this end we use a real-time 3D reconstruction system which builds a 3D-representation of all the objects in the room. The reconstructed 3D-representation of the physician is then tracked over time and at each time step in which the X-Ray source is used the radiation received by each body part is accumulated. To simulate the radiation we use a physics-based simulation package. The physician can review his radiation exposure after the intervention and use the collected radiation information over a longer time period in order to minimize his radiation exposure by adjusting his positioning relative to the X-ray source. The system can also be used as an awareness tool for less experienced physicians.