The ARIA trial protocol: a randomised controlled trial to assess the clinical, technical, and cost-effectiveness of a cloud-based, ARtificially Intelligent image fusion system in comparison to standard treatment to guide endovascular Aortic aneurysm repair.

BACKGROUND: Endovascular repair of aortic aneurysmal disease is established due to perceived advantages in patient survival, reduced postoperative complications, and shorter hospital lengths of stay. High spatial and contrast resolution 3D CT angiography images are used to plan the procedures and inform device selection and manufacture, but in standard care, the surgery is performed using image-guidance from 2D X-ray fluoroscopy with injection of nephrotoxic contrast material to visualise the blood vessels. This study aims to assess the benefit to patients, practitioners, and the health service of a novel image fusion medical device (Cydar EV), which allows this high-resolution 3D information to be available to operators at the time of surgery. METHODS: The trial is a multi-centre, open label, two-armed randomised controlled clinical trial of 340 patient, randomised 1:1 to either standard treatment in endovascular aneurysm repair or treatment using Cydar EV, a CE-marked medical device comprising of cloud computing, augmented intelligence, and computer vision. The primary outcome is procedural time, with secondary outcomes of procedural efficiency, technical effectiveness, patient outcomes, and cost-effectiveness. Patients with a clinical diagnosis of AAA or TAAA suitable for endovascular repair and able to provide written informed consent will be invited to participate. DISCUSSION: This trial is the first randomised controlled trial evaluating advanced image fusion technology in endovascular aortic surgery and is well placed to evaluate the effect of this technology on patient outcomes and cost to the NHS. TRIAL REGISTRATION: ISRCTN13832085. Dec. 3, 2021.

Fully automated 2D-3D registration and verification.

Clinical application of 2D-3D registration technology often requires a significant amount of human interaction during initialisation and result verification. This is one of the main barriers to more widespread clinical use of this technology. We propose novel techniques for automated initial pose estimation of the 3D data and verification of the registration result, and show how these techniques can be combined to enable fully automated 2D-3D registration, particularly in the case of a vertebra based system. The initialisation method is based on preoperative computation of 2D templates over a wide range of 3D poses. These templates are used to apply the Generalised Hough Transform to the intraoperative 2D image and the sought 3D pose is selected with the combined use of the generated accumulator arrays and a Gradient Difference Similarity Measure. On the verification side, two algorithms are proposed: one using normalised features based on the similarity value and the other based on the pose agreement between multiple vertebra based registrations. The proposed methods are employed here for CT to fluoroscopy registration and are trained and tested with data from 31 clinical procedures with 417 low dose, i.e. low quality, high noise interventional fluoroscopy images. When similarity value based verification is used, the fully automated system achieves a 95.73% correct registration rate, whereas a no registration result is produced for the remaining 4.27% of cases (i.e. incorrect registration rate is 0%). The system also automatically detects input images outside its operating range.

Interventional digital tomosynthesis from a standard fluoroscopy system using 2D-3D registration.

Interventional fluoroscopy provides guidance in a variety of minimally invasive procedures. However, three-dimensional (3D) clinically relevant information is projected onto a two-dimensional (2D) image which can make image interpretation difficult. Moreover, vasculature visualisation requires the use of iodinated contrast media which is nephrotoxic and is the primary cause of renal complications. In this article, we demonstrate how digital tomosynthesis slices can be produced on standard fluoroscopy equipment by registering the preoperative CT volume and the intraoperative fluoroscopy images using 2D-3D image registration. The proposed method automatically reconstructs patient-anatomy-specific slices and removes clutter resulting from bony anatomy. Such slices could provide additional intraoperative information which cannot be provided by the preoperative CT volume alone, such as the deformed aorta position offering improved guidance precision. Image acquisition would fit with interventional clinical work-flow and would not require a high X-ray dose. Experiments are carried out using one phantom and four clinical datasets. Phantom results showed a 3351% contrast-to-noise improvement compared to standard fluoroscopy. Patient results showed our method enabled visualization of clinically relevant features: outline of the aorta, the aortic bifurcation and some aortic calcifications.

Coagulopathy associated with sac reperfusion for reversing paraplegia after endovascular repair of type II thoracoabdominal aneurysm.

Sac perfusion may be helpful in preventing or reversing spinal cord injury after endovascular repair of thoracoabdominal aneurysms and it has been used as an adjunct to the standard physiologic measures of sustained hypertension and cerebrospinal fluid drainage. Coagulopathy as a result of endoleak after endovascular aneurysm repair has been reported, and very rare cases of treatment after repair of these endoleaks have been described. We report a 73-year-old man who had endovascular repair of a type II thoracoabdominal aneurysm with a branched stent graft. Sac reperfusion was initiated to manage postoperative paraplegia. The paraplegia partially resolved but severe hemorrhagic complications developed that were attributed to sac perfusion-related hyperfibrinolysis. Discontinuation of sac perfusion resolved the coagulopathy but resulted in paraplegia.

Increasing the automation of a 2D-3D registration system.

Routine clinical use of 2D-3D registration algorithms for Image Guided Surgery remains limited. A key aspect for routine clinical use of this technology is its degree of automation, i.e., the amount of necessary knowledgeable interaction between the clinicians and the registration system. Current image-based registration approaches usually require knowledgeable manual interaction during two stages: for initial pose estimation and for verification of produced results. We propose four novel techniques, particularly suited to vertebra-based registration systems, which can significantly automate both of the above stages. Two of these techniques are based upon the intraoperative "insertion" of a virtual fiducial marker into the preoperative data. The remaining two techniques use the final registration similarity value between multiple CT vertebrae and a single fluoroscopy vertebra. The proposed methods were evaluated with data from 31 operations (31 CT scans, 419 fluoroscopy images). Results show these methods can remove the need for manual vertebra identification during initial pose estimation, and were also very effective for result verification, producing a combined true positive rate of 100% and false positive rate equal to zero. This large decrease in required knowledgeable interaction is an important contribution aiming to enable more widespread use of 2D-3D registration technology.

Systematic review and meta-analysis of open surgical and endovascular management of thoracic outlet vascular injuries.

BACKGROUND: Junctional vascular trauma such as that at the thoracic outlet poses particular challenges in surgical management. The use of endovascular techniques for such injuries is attractive as repair may be facilitated without the need for thoracotomy; however, the utility of such techniques is currently based on opinion, small retrospective series, and literature reviews of narrative and not systematic quality. The objective of this study is to provide a complete and systematic analysis of the literature pertaining to open surgery (OS) and endovascular management (EM) of thoracic outlet vascular injuries. METHODS: An electronic search using the MEDLINE, Embase, Cochrane Library, Science Citation Index, and LILACS databases was performed for articles published from 1947 to November 2011. The review conformed to the Preferred Reporting Items for Systematic Reviews and Meta-analyses statement standards. Prospective studies and retrospective cohorts of more than 10 patients were included. The primary outcome was all-cause mortality. RESULTS: One prospective noncomparative study and 73 retrospective series met the inclusion criteria. There were no randomized studies. All studies were at high risk of bias. Fifteen studies described outcomes for both OS and EM (549 patients). The majority of these studies described EM for traumatic arteriovenous fistulas or false aneurysms in stable patients. Direct comparison between OS and EM was possible in only three studies (comprising 23 OS and 25 EM patients), which showed no difference in all-cause mortality (odds ratio, 0.67; 95% confidence interval [CI], 0.11-4.05), but a shorter operating time with EM (mean difference = 58.34 minutes; 95% CI, 17.82-98.85). These three series included successful EM of unstable patients and those with vessel transection. There were 55 studies describing only OS (2057 patients) with a pooled mortality rate of 12.4% (95% CI, 9.9%-15.2%). Four studies described only EM (101 patients) with a pooled mortality rate of 26% (95% CI, 8%-51%), but these represented a distinct subgroup of cases (mainly iatrogenic injuries in older patients). CONCLUSIONS: The current evidence is weak and fails to show superiority of one modality over the other. EM is currently used primarily in highly selected cases, but there are reports of a broader applicability in trauma. High-quality randomized studies or large-scale registry data are needed to further comment on the relative merits or disadvantages of EM in comparison to OS.

Interventional digital tomosynthesis from a standard fluoroscopy system using 2D-3D registration.

Fluoroscopy is the mainstay of interventional radiology. However, the images are 2D and visualisation of vasculature requires nephrotoxic contrast. Cone-beam computed tomography is often available, but involves large radiation dose and interruption to clinical workflow. We propose the use of 2D-3D image registration to allow digital tomosynthesis (DTS) slices to be produced using standard fluoroscopy equipment. Our method automatically produces patient-anatomy-specific slices and removes clutter resulting from bones. Such slices could provide additional intraoperative information, offering improved guidance precision. Image acquisition would fit with interventional clinical workflow and would not require a high x-ray dose. Phantom results showed a 1133% contrast-to-noise improvement compared to standard fluoroscopy. Patient results showed our method enabled visualisation of clinically relevant features: outline of the aorta, the aortic bifurcation and some aortic calcifications.

Non-rigid 2D-3D registration using anisotropic error ellipsoids to account for projection uncertainties during aortic surgery.

Overlay of preoperative images is increasingly being used to aid complex endovascular aortic repair and is obtained by rigid 2D-3D registration of 3D preoperative (CT) and 2D intraoperative (X-ray) data. However, for tortuous aortas large non-rigid deformations occur, thus a non-rigid registration must be performed to enable an accurate overlay. This article proposes the use of Thin-Plate Splines (TPS) to perform non-rigid 2D-3D registration. Intraoperative X-ray data contain no spatial information along the X-ray projection direction. Our approach accounts for this lack of spatial information by the use of an approximating TPS with non-isotropic error ellipsoids, where the major ellipsoid axis is aligned with the X-ray projection direction. Experiments are carried out using 1D-2D and 2D-3D simulated data and 2D-3D interventional data. Simulated results show that our proposed method is 1.5 times more accurate than interpolating TPS based registration. Interventional data results show how large rigid registration errors of 9mm can be reduced to 4mm using our proposed method.

Stent-graft limb deployment in the external iliac artery increases the risk of limb occlusion following endovascular AAA repair.

PURPOSE: To assess whether deployment of an endograft limb in the external iliac artery (EIA) increases the rate of limb occlusion following endovascular aneurysm repair (EVAR). METHODS: Interrogation of a prospectively maintained database identified 661 patients (596 men; median age 73 years, range 37-93) with infrarenal abdominal aortic aneurysm who underwent EVAR between 1996 and 2010 using Zenith stent-grafts predominately. Of these, 567 patients [56 (9.9%) women] had both endograft limbs deployed in the CIA (1203 limbs at risk), while 94 patients [9 (9.6%) women] had at least 1 limb in the EIA (22 bilateral; 116 limbs at risk). An adjunctive bare metal stent was used in 8 (9%) limbs deployed in the EIA. RESULTS: There were 31 limb occlusions, all unilateral: 17 (3%) patients in the CIA group had an occluded limb (1% of limbs at risk) vs. 14 (15%) patients in the EIA group (12% of limbs at risk; p<0.0001). The median time to occlusion was 3 months (0-60) in the CIA group and 1 month (0-36) in the EIA group. The majority of occlusions were treated by extra-anatomical revascularization, most often a femorofemoral crossover bypass. No legs were amputated following occlusion of a limb placed in the CIA, but there were 3 amputations in the EIA group (p=0.003). CONCLUSION: Deployment of endograft limbs into the EIA led to a higher rate of occlusion and leg amputation. Increased tortuosity of the EIA and a smaller caliber vessel are likely to account for the increased risk.

Use of a remotely steerable "robotic" catheter in a branched endovascular aortic graft.

We report the use of a remotely steerable catheter to treat kinked renal bridging stents 8 months after branched endovascular repair of a type III thoracoabdominal aortic aneurysm. Conventional techniques using single, coaxial, and manually steerable sheaths proved too unstable to provide the support required to pass a wire against resistance through the kinked stent. A remotely steerable "robotic" catheter provided sufficient precision and stability to cross the kink and reline it with an additional stent, restoring renal perfusion. This technology can help achieve precise and stable introducer sheath position. Further evaluation is necessary to understand the wider applications.

Endovascular treatment of acute aortic syndrome.

BACKGROUND: The term acute aortic syndrome (AAS) encompasses a range of conditions that have a risk of imminent aortic rupture and where delays in treatment result in increased mortality. Endovascular treatment offers an attractive alternative to open surgery but little is known about the durability of the repair and the factors that predict mortality. METHODS: Prospective data were collected for a cohort of 110 consecutive patients with endovascular treatment for AAS. Patient and procedural characteristics were related to short- and midterm outcome using multivariate logistic regression analysis. RESULTS: There were 75 men and 35 women with a median age of 68 (range 57-76) years. The pathologies treated were acute dissection (35), symptomatic aneurysm (32), infected aneurysm (18), transection (12), chronic dissection (9), penetrating ulcer (3), and intramural hematoma (1). Thirty-day mortality was 12.7% and this was associated with hypotension (odds ratio [OR], 5.25), use of general anesthetic (OR, 5.23), long procedure duration (OR, 2.03), and increasing age (OR, 1.07). The causes of death were aortic rupture (4), myocardial infarction (4), stroke (3), and multisystem organ failure (3). The stroke and paraplegia rates were 7.3% and 6.4%, respectively. The 1-year survival was 81% and the 5-year survival 63%. Secondary procedures were required in 13 (11.8%) patients. Factors associated with death at 1 year were presence of an aortic fistula (OR, 9.78), perioperative stroke (OR, 5.87), and use of general anesthetic (OR, 3.76); and at 5 years were aortic fistula (OR, 12.31) and increasing age (OR, 1.06). CONCLUSIONS: Acute aortic syndrome carries significant early and late mortality. Emergency endovascular repair offers a minimally invasive treatment option associated with acceptable short and midterm results. Continued surveillance is important as secondary procedures and aortic-related deaths continue to occur throughout the follow-up period.

Endovascular management of Stanford type a dissection or intramural hematoma with a distal primary entry tear.

A systematic review was conducted of all published cases of endovascular repair of retrograde Stanford type A dissection or intramural hematoma to determine mortality of this less invasive approach to treatment. Using the PRISMA guidelines, databases were searched for any of the terms 'dissect$', 'IMH', ('aortic ADJ wall'), 'intramur$', 'intra-mur$' in combination with any of 'stent$', 'perc$', 'endo$', 'TEVAR' in combination with any of ('type ADJ A'), 'ascend$' and 'retro$.' The search retrieved 3131 titles, 280 abstracts, and 108 papers. Of 23 relevant papers selected, mortality data could be extracted from 11 studies, representing 60 patients. Overall in-hospital mortality was 1.8% (95% CI 1.2% to 2.4%). Additional all-cause mortality during follow-up was 5.4% (95% CI 3.5% to 7.2%). The placement of an endoluminal device in the descending thoracic aorta to treat a DeBakey IIId/retrograde type A aortic dissection or intramural hematoma may be a safer procedure in the short to medium term than open surgical replacement of the ascending aorta (with or without the arch). Open surgical repair in these patients may therefore be unjustified.

Predictors of reintervention after endovascular repair of isolated iliac artery aneurysm.

The objective of this study was to identify factors predicting the need for reintervention after endovascular repair of isolated iliac artery aneurysm (IIAA). We reviewed prospectively collected database records of all patients who underwent endovascular repair of IIAA between 1999 and 2008. Detailed assessment of the aneurysms was performed using computed tomography angiography (CTA). Follow-up protocol included CTA at 3 months. If this showed no complication, then annual duplex scan was arranged. Multivariate analysis and analysis of patient survival and freedom from reintervention were performed using Kaplan-Meier life tables. Forty IIAAs (median diameter 44 mm) in 38 patients were treated (all men; median age 75 years), and median follow-up was 27 months. Endovascular repair of IIAA was required in 14 of 40 aneurysms (35%). The rate of type I endoleak was significantly higher with proximal landing zone (PLZ) diameter >30 mm in the aorta or >24 mm in the common iliac artery or distal landing zone (DLZ) diameter >24 mm (P = 0.03, 0.03, and 0.0014, respectively). Reintervention rate (RR) increased significantly with increased diameter or decreased length of PLZ; increased DLZ diameter; and endovascular IIAA repair (P = 0.005, 0.005, 0.02, and 0.02 respectively); however, RR was not significantly affected by length of PLZ or DLZ. Freedom-from-reintervention was 97, 93, and 86% at 12, 24, and 108 months. There was no in-hospital or aneurysm-related mortality. Endovascular IIAA repair is a safe treatment option. Proper patient selection is essential to decrease the RR.

Feasibility and limitations of an automated 2D-3D rigid image registration system for complex endovascular aortic procedures.

PURPOSE: To examine the feasibility of an automated 2-dimensional (2D) to 3- dimensional (3D) image registration system to simplify the navigational challenges faced in complex endovascular aortic procedures. METHODS: An automated 2D-3D image registration system was used to overlay pre-acquired 3D computed tomography images onto fluoroscopy images taken during endovascular aneurysm repair. Errors between the 3D overlay and digital subtraction angiograms were measured and correlated with aortic neck angulation. A mean discrepancy < or =3 mm was considered clinically acceptable. RESULTS: There was a strong correlation between maximum neck angulation and maximum registration error (Pearson's r = 0.75). Aortas with a maximum neck angulation < or =30 degrees had a mean error of 2.5+/-1.2 mm, whereas aortas with neck angulation >30 degrees had a mean error of 6.2+/-2.5 mm (p<0.0001). CONCLUSION: The major source of registration errors is aortic deformation caused by the presence of the introducer and endovascular graft. Further work is required if this technology is to be routinely applied to severely angulated aortic anatomy.

Emergency endovascular aneurysm repair for ruptured abdominal aortic aneurysm: the way forward?

We present the early results of a policy of treating all anatomically suitable ruptured abdominal aortic aneurysms (rAAAs) by emergency endovascular aneurysm repair (eEVAR), regardless of hemodynamic instability. Data were retrospectively collected from prospectively maintained databases identifying patients with rAAA from 2006 to 2007. Forty-seven patients with true rAAA were identified (87% men; median age 76 years [range 63-97 years]), of whom 18 (38%) were treated with eEVAR, 19 (40%) received open aneurysm repair (OAR), and 10 (21%) were managed nonoperatively. Fifteen of 18 (83%) eEVAR patients received an aortouni-iliac device + femorofemoral crossover, 2 patients (11%) had bifurcated devices, and 1 patient (6%) had a new iliac limb. Thirty-day mortality was 11% (2 of 18) for eEVAR and 32% (6 of 19) for OAR (p = not significant). At the 6-month follow-up, mortality was 22% (4 of 18) for eEVAR and 37% (7 of 19) for OAR (p = not significant). A clinically significant early survival advantage is suggested for eEVAR in patients presenting with rAAA.

Endovascular repair of a tuberculous mycotic thoracic aortic aneurysm with a custom-made device.

Mycotic aortic aneurysms are rare and it is unlikely that any center will obtain extensive experience in their management. The aim of treatment is to repair the aorta and eradicate the infection with minimal operative and postoperative risk. We describe a case in which a custom-made endovascular stent graft provided the optimal treatment strategy and remained durable at 4 years of follow-up.

Results of endovascular repair of abdominal aortic aneurysms with an unfavorable proximal neck using large stent-grafts.

The purpose of this study was to evaluate the early outcome of endovascular repair of abdominal aortic aneurysms (EVAR) with an unfavorable neck anatomy using extralarge stent-grafts. We carried out a retrospective review of all patients who underwent elective EVAR using large diameter stent-grafts between June 2006 and February 2008. All patients had computed tomography angiography (CTA) for procedure planning, and detailed assessment of the aneurysm neck was performed using a three-dimensional CTA workstation. All patients were followed up with CTA at 3 and 12 months and annual duplex thereafter when appropriate. This analysis included 25 patients (23 men, 2 woman; median age, 76 years; age range, 60-88 years). The median aneurysm diameter was 7 cm, and the median aneurysm neck diameter was 31 mm. Extralarge Cook-Zenith stent-grafts were used in all patients, with a top-end diameter of 36 mm (n=23) and 40 mm (n=2). The follow-up period ranged from 3 to 24 months, with a median of 6 months. Primary and assisted primary technical success rates were 80% and 96%, respectively. Reintervention was required to treat proximal type I endoleak (n=1), iliac limb kink (n=2), and occluded femorofemoral crossover graft (n=1). These early results show that EVAR using extralarge stent-grafts with suprarenal fixation can be a reliable modality to treat infrarenal aortic aneurysms with an unfavorable neck anatomy.

Peripheral endografts for the treatment of traumatic arterial injuries.

Catheter-based endovascular techniques for vascular trauma management are being increasingly reported. Covered stents may be inserted and deployed through a remote site of percutaneous access under local anesthesia and are ideal for treating arterial ruptures and pseudoaneurysms and to seal off arteriovenous communications. Advantages of endovascular stent-graft repair of peripheral traumatic arterial injuries include less blood loss and tissue damage, reduced operative time and morbidity, shortened hospital stay and recovery periods, and reduced healthcare costs. The present report provides an overview of the role of balloon-expandable and self-expandable covered stents in the minimally invasive treatment of various types of traumatic arterial injuries.

Vowel Recognition from Articulatory Position Time-Series Data.

A new approach of recognizing vowels from articulatory position time-series data was proposed and tested in this paper. This approach directly mapped articulatory position time-series data to vowels without extracting articulatory features such as mouth opening. The input time-series data were time-normalized and sampled to fixed-width vectors of articulatory positions. Three commonly used classifiers, Neural Network, Support Vector Machine and Decision Tree were used and their performances were compared on the vectors. A single speaker dataset of eight major English vowels acquired using Electromagnetic Articulograph (EMA) AG500 was used. Recognition rate using cross validation ranged from 76.07% to 91.32% for the three classifiers. In addition, the trained decision trees were consistent with articulatory features commonly used to descriptively distinguish vowels in classical phonetics. The findings are intended to improve the accuracy and response time of a real-time articulatory-to-acoustics synthesizer.