Augmented reality simulator for CT-guided interventions.

INTRODUCTION: CT-guided interventions are taught using a mentored approach on real patients. It is well established that simulation is a valuable training tool in medicine. This project assessed the feasibility and acceptance of replicating a CT-guided intervention using a bespoke software application with an augmented reality head-mounted display (ARHMD). METHODS: A virtual patient was generated using a CT dataset obtained from The Cancer Imaging Archive. A surface mesh of a virtual patient was projected into the field-of-view of the operator. ChArUco markers, placed on both the needle and agar jelly phantom, were tracked using RGB cameras built into the ARHMD. A virtual CT slice simulating the needle position was generated on voice command. The application was trialled by senior interventional radiologists and trainee radiologists with a structured questionnaire evaluating face validity and technical aspects. RESULTS: Sixteen users trialled the application and feedback was received from all. Eleven felt the accuracy and realism was adequate for training and twelve felt more confident about their CT biopsy skills after this training session. DISCUSSION: The study showed the feasibility of simulating a CT-guided procedure with augmented reality and that this could be used as a training tool. KEY POINTS: • Simulating a CT-guided procedure using augmented reality is possible. • The simulator developed could be an effective training tool for clinical practical skills. • Complexity of cases can be tailored to address the training level demands.

Early outcomes of patients transferred with ruptured suprarenal aneurysm or dissection.

Objective Despite centralisation of the provision of vascular care, not all areas in England and Wales are able to offer emergency treatment for patients with acute conditions affecting the aorta proximal to the renal arteries. While cardiothoracic centres have made network arrangements to coordinate care for the repair of type A dissections, a similar plan for vascular care is lacking. This study investigates early outcomes in patients with ruptured suprarenal aortic aneurysm or dissection (rSRAD) transferred to a specialist centre. Methods Retrospective observational study over a five-year period (2009-2014) assessing outcomes of patients with ruptured sRAD diagnosed at their local hospital and then transferred to a tertiary centre capable of offering such treatment. Results Fifty-two patients (median age 73 years, 32 male) with rSRAD were transferred and a further four died during transit. The mean distance of patient transfer was 35 miles (range 4-211 miles). One patient did not undergo intervention due to frailty and two died before reaching the operating theatre. A total of 23 patients underwent endovascular repair, 9 hybrid repair and 17 open surgery. Median follow-up was 12 months (range 1-43 months). Complications included paraplegia (n = 3), stroke (n = 2), type IA endoleak (n = 4); 30-day and in-hospital mortality were 16% and 27%. For patients discharged alive from hospital, one-year survival was 67%. Conclusions Although the number of patients with rSRAD is low and those who are transferred alive are a self-selecting group, this study suggests that transfer of such patients to a specialist vascular centre is associated with acceptable mortality rates following emergency complex aortic repair.

Cerebral embolization, silent cerebral infarction and neurocognitive decline after thoracic endovascular aortic repair.

BACKGROUND: Silent cerebral infarction is brain injury detected incidentally on imaging; it can be associated with cognitive decline and future stroke. This study investigated cerebral embolization, silent cerebral infarction and neurocognitive decline following thoracic endovascular aortic repair (TEVAR). METHODS: Patients undergoing elective or emergency TEVAR at Imperial College Healthcare NHS Trust and Guy's and St Thomas' NHS Foundation Trust between January 2012 and April 2015 were recruited. Aortic atheroma graded from 1 (normal) to 5 (mobile atheroma) was evaluated by preoperative CT. Patients underwent intraoperative transcranial Doppler imaging (TCD), preoperative and postoperative cerebral MRI, and neurocognitive assessment. RESULTS: Fifty-two patients underwent TEVAR. Higher rates of TCD-detected embolization were observed with greater aortic atheroma (median 207 for grade 4-5 versus 100 for grade 1-3; P = 0·042), more proximal landing zones (median 450 for zone 0-1 versus 72 for zone 3-4; P = 0·001), and during stent-graft deployment and contrast injection (P = 0·001). In univariable analysis, left subclavian artery bypass (ß coefficient 0·423, s.e. 132·62, P = 0·005), proximal landing zone 0-1 (ß coefficient 0·504, s.e. 170·57, P = 0·001) and arch hybrid procedure (ß coefficient 0·514, s.e. 182·96, P < 0·001) were predictors of cerebral emboli. Cerebral infarction was detected in 25 of 31 patients (81 per cent) who underwent MRI: 21 (68 per cent) silent and four (13 per cent) clinical strokes. Neurocognitive decline was seen in six of seven domains assessed in 15 patients with silent cerebral infarction, with age a significant predictor of decline. CONCLUSION: This study demonstrates a high rate of cerebral embolization and neurocognitive decline affecting patients following TEVAR. Brain injury after TEVAR is more common than previously recognized, with cerebral infarction in more than 80 per cent of patients.

Assessing the effects of manual dexterity and playing computer games on catheter-wire manipulation for inexperienced operators.

AIM: To investigate the effect of playing computer games and manual dexterity on catheter-wire manipulation in a mechanical aortic model. MATERIAL AND METHODS: Medical student volunteers filled in a preprocedure questionnaire assessing their exposure to computer games. Their manual dexterity was measured using a smartphone game. They were then shown a video clip demonstrating renal artery cannulation and were asked to reproduce this. All attempts were timed. Two-tailed Student's t-test was used to compare continuous data, while Fisher's exact test was used for categorical data. RESULTS: Fifty students aged 18-22 years took part in the study. Forty-six completed the task at an average of 168 seconds (range 103-301 seconds). There was no significant difference in the dexterity score or time to cannulate the renal artery between male and female students. Students who played computer games for >10 hours per week had better dexterity scores than those who did not play computer games: 9.1 versus 10.2 seconds (p=0.0237). Four of 19 students who did not play computer games failed to complete the task, while all of those who played computer games regularly completed the task (p=0.0168). CONCLUSION: Playing computer games is associated with better manual dexterity and ability to complete a basic interventional radiology task for novices.

Robotic Arch Catheter Placement Reduces Cerebral Embolization During Thoracic Endovascular Aortic Repair (TEVAR).

OBJECTIVE: Stroke caused by cerebral embolization constitutes a principal risk during arch manipulation and thoracic endovascular aortic repair (TEVAR). This study investigates the incidence of cerebral embolization during catheter placement in the aortic arch, and compares robotic and manual techniques. METHODS: Intra-operative transcranial Doppler (TCD) was performed in 11 patients undergoing TEVAR. Wire and catheter placement in the arch was performed by two experienced operators. Manual and robotic catheter placement and removal were compared for each patient; 44 manoeuvres were studied in total. A conventional 5Fr pigtail catheter was used for manual cannulation via a 5Fr access sheath. The 6Fr/9Fr co-axial Magellan endovascular robotic system was used for robotic navigation operated from a remote workstation. The number of high intensity transient signals (HITS) detected by TCD during different stages of TEVAR was recorded. RESULTS: The median procedural embolization rate was 173 (interquartile range 97-240). There were significantly fewer HITS detected during robotic catheter placement with six in total (median 0, IQR 0-1), compared with 38 HITS (median 2, IQR 1-5) during manual catheter placement (p = .018). There were no HITS detected during robotic catheter removal by auto-retraction as per manufacturer instructions. On two occasions, however, when the robotic catheter system was removed manually without correcting for articulation, it resulted in one HIT in one case and 11 HITS in the second case. CONCLUSIONS: Robotic catheter placement is feasible during TEVAR, and results in significantly less cerebral embolization compared with manual techniques. The active manoeuvrability, control, and stability of the robotic system is likely to reduce contact with an atheromatous aortic arch wall, and thereby reduce dislodgement of particulate matter and result in less embolization. The importance of adhering to manufacturer instructions during use and removal of the robotic catheter is also highlighted.

Long-term results of intra-arterial onyx injection for type II endoleaks following endovascular aneurysm repair.

Purpose The aim of this paper is to report our experience of type II endoleak treatment after endovascular aneurysm repair with intra-arterial injection of the embolizing liquid material, Onyx liquid embolic system. Methods From 2005 to 2012, we performed a retrospective review of 600 patients, who underwent endovascular repair of an abdominal aortic aneurysm. During this period, 18 patients were treated with Onyx for type II endoleaks. Principal findings The source of the endoleak was the internal iliac artery in seven cases, inferior mesenteric artery in seven cases and lumbar arteries in four cases. Immediate technical success was achieved in all patients and no endoleak from the treated vessel recurred. During a mean follow-up of 19 months, no major morbidity or mortality occurred, and one-year survival was 100%. Conclusions Treatment of type II endoleaks with Onyx is safe and effective over a significant time period.

A Systematic Review of Outcomes Following Percutaneous Transluminal Angioplasty and Stenting in the Treatment of Transplant Renal Artery Stenosis.

PURPOSE: To evaluate outcomes following treatment of transplant renal artery stenosis by percutaneous transluminal angioplasty and stent insertion. MATERIALS AND METHODS: A literature search was performed using Pubmed, MEDLINE, Embase, Wiley Interscience and the Cochrane Library databases. Outcome measures were glomerular filtration rate, creatinine, blood pressure and number of antihypertensive medications. Technical and clinical success, patency and complication rates were also analysed. RESULTS: Thirty-two studies met the inclusion criteria, involving a total of 884 interventions including PTA, stenting, or combinations of both. Clinical success rates were in the range 65.5-94%. The majority of studies reported technical success rates higher than 90%. Patency rates were in the range of 42-100%. However, the definition and diagnostic criteria for TRAS varied widely between studies. Also, marked heterogeneity was observed in the reporting of outcome measures with no consensus in outcome criteria or follow up schedule. CONCLUSION: Outcomes following PTA and stenting for the treatment of TRAS have been shown to be favourable. However, there is a distinct lack of well designed studies assessing outcomes following intervention. Outcome reporting may be improved by the introduction of standardised outcome measures with reporting of outcomes into a multi-centre registry.

Variation in maximum diameter measurements of descending thoracic aortic aneurysms using unformatted planes versus images corrected to aortic centerline.

OBJECTIVE: Evaluation of variation in descending thoracic aortic aneurysm (dTAA) diameters measured on CT scans in different planes and by different observers and the potential impact on treatment decisions. METHODS: CT angiography of dTAA (N = 20) were assessed by three specialists, with measurements repeated after 1 month. Calliper measurements of maximum external diameters were made on unformatted images and perpendicular to the aneurysm centerline after image processing (corrected). Repeatability was assessed using Bland-Altman plots. RESULTS: Maximum corrected diameter measurements were smaller than axial measurements (66.3 ± 7.9 mm vs. 74.9 ± 20.9 mm, p < .001). Both intraobserver and interobserver variation were less for corrected than for axial measurements (mean intraobserver differences 5.0 ± 3.8 mm vs. 11.8 ± 9.3 mm, p < .001; mean interobserver differences 2.8 ± 2.5 mm versus 10.4 ± 14.0 mm, p < .001) and interobserver variation increased with aneurysm diameter for maximum axial but not corrected measurements. Using corrected rather than axial measurements could have changed treatment decisions in two patients (10%) using a treatment threshold diameter of 55 mm and 10 patients (50%) using a threshold of 65 mm. CONCLUSION: Corrected diameters were smaller than axial diameters, could be measured with higher repeatability, and were subject to less interobserver variability. Using corrected versus axial measurements would have changed management decisions in up to half of the cases in this study.

Postanastomotic transplant renal artery stenosis: association with de novo class II donor-specific antibodies.

In this study, we analyze the outcomes of transplant renal artery stenosis (TRAS), determine the different anatomical positions of TRAS, and establish cardiovascular and immunological risk factors associated with its development. One hundred thirty-seven of 999 (13.7%) patients had TRAS diagnosed by angiography; 119/137 (86.9%) were treated with angioplasty, of which 113/137 (82.5%) were stented. Allograft survival in the TRAS+ intervention, TRAS+ nonintervention and TRAS- groups was 80.4%, 71.3% and 83.1%, respectively. There was no difference in allograft survival between the TRAS+ intervention and TRAS- groups, p = 0.12; there was a difference in allograft survival between the TRAS- and TRAS+ nonintervention groups, p < 0.001, and between the TRAS+ intervention and TRAS+ nonintervention groups, p = 0.037. TRAS developed at the anastomosis, within a bend/kink or distally. Anastomotic TRAS developed in living donor recipients; postanastomotic TRAS (TRAS-P) developed in diabetic and older patients who received grafts from deceased, older donors. Compared with the TRAS- group, patients with TRAS-P were more likely to have had rejection with arteritis, odds ratio (OR): 4.83 (1.47-15.87), p = 0.0095, and capillaritis, OR: 3.03 (1.10-8.36), p = 0.033. Patients with TRAS-P were more likely to have developed de novo class II DSA compared with TRAS- patients hazard ratio: 4.41 (2.0-9.73), p < 0.001. TRAS is a heterogeneous condition with TRAS-P having both alloimmune and traditional cardiovascular risk factors.

Planning for EVAR: the role of modern software.

Endovascular intervention has revolutionized the treatment of aortic disease, extending the cohort of patients eligible for repair. Accurate planning for endovascular aortic repair is essential. Recent advances in modern software have demonstrated potential for improving outcomes and enhancing the decision making process beyond 3D measurements and intraoperative navigation techniques. With increasing uptake and complexity of endovascular therapies requiring multidisciplinary collaborations, it has become apparent that planning must extend to the preparation of entire interventional teams and support the early identification and prevention of potentially harmful events. This paper will examine recent advances not only in morphological planning and computational modelling, but also the role of software in the preparation of teams and prevention of error.

A pilot study of video-motion analysis in endovascular surgery: development of real-time discriminatory skill metrics.

OBJECTIVES: Accurate assessment and credentialing of physicians is essential. Objective motion analysis of guide-wire/catheter manipulation to assess proficiency during endovascular interventions remains unexplored. This study aims to assess its feasibility and its role in evaluation of technical ability. MATERIALS AND METHODS: A semi-automated catheter-tracking software was developed which allows for frame-by-frame motion analysis of fluoroscopic videos and calculation 2D catheter tip path-length. 21 interventionalists (6 cardiologists, 8 interventional radiologists, 7 vascular surgeons; 14/21 had performed >500 endovascular procedures) performed an identical carotid artery stenting procedure (CAS) on a VIST simulator (Mentice, Gothenburg, Sweden). Operators were sub-divided into four categories according to CAS experience: 6 inexperienced (0 CAS-group A), 3 low-volume (1-20 CAS-group B), 5 moderate-volume (21-50 CAS-group C) and 7 high-volume (>50 CAS-group D) CAS experience. Total PL was calculated for each case and comparisons made between groups. PL was correlated with: quantitative, simulator-derived metrics and qualitative performance scores (generic and procedure-specific) derived from post-hoc video analysis by three blinded observers. RESULTS: Group D used 5160.3 (inter-quartile range- IQR 4046.4-7142.9) pixels of movement, compared to 6856.7 (5914.4-8106.9) for group A (p = 0.046); 10,905.1 (7851.1-14,381.5) for group B (p = 0.017); and 9482.6 (8663.5-13,847.6) for group C (p = 0.003). Statistically significant inverse correlations were seen between total PL and qualitative performance scores (rho = -0.519 for generic (p = 0.027) rho = -0.567 for procedure-specific (p = 0.014) scores). PL did not correlate with any of the simulator-derived metrics (errors, contrast volume, total procedure and fluoroscopy times, cine-loops used). CONCLUSION: Endovascular instrument video motion analysis is feasible and may represent a valuable tool for the objective assessment of endovascular skill.

A comparison of the quality of the information available on the internet on interventional radiology, vascular surgery, and cardiology.

CONTEXT AND AIMS: Internet use is rapidly expanding and increasingly plays a substantial role in patient education. We sought to evaluate and compare the quality of information available to patients online on three closely linked specialties: Interventional radiology (IR), cardiology, and vascular surgery. MATERIALS AND METHODS: We searched the leading three search engines for the terms: "Interventional Radiology", "cardiology," and "vascular surgery," collating the top 50 hits from each search. After excluding duplicates and irrelevant sites, 43, 25, and 36 sites remained, respectively. Sites were analyzed using the LIDA instrument (an online tool for assessing health-related websites) and Fleisch Reading Ease Scores (FRES) were compared across the different search terms and correlated with the country of origin and certification by the Health on the Net (HON) Foundation. RESULTS: There was no significant difference ( P>0.05) in the total LIDA, accessibility, usability or reliability scores between the three specialties. HONCode certification was associated with higher LIDA (83.1±1.6 vs. 71.53±0.8 ( P<0.0001)), reliability (75.7±3.6 vs. 49.0±1.6 ( P<0.0001)) and FRES (37.4±4.0 vs. 29.7±1.4 ( P=0.0441)). CONCLUSION: Websites are generally well designed and easy to use; the majority however, lacks currency and reliability. Despite similarity in quality of online information, there is a disparity in knowledge of IR; this may be due to low web-traffic figures of IR sites. Wikipedia's user-generated content, ranks highly in major search engines, as such; this could serve as means of disseminating reliable health information to patients.

Design and validation of an error capture tool for quality evaluation in the vascular and endovascular surgical theatre.

BACKGROUND: The unique and complex vascular and endovascular theatre environment is associated with significant risks of patient harm and procedural inefficiency. Accurate evaluation is crucial to improve quality. This pilot study attempted to design a valid, reproducible tool for observers and teams to identify and categorise errors. METHODS: Relevant published literature and previously collected ethnographic field notes from over 250 h of arterial surgery were analysed. A comprehensive log of vascular procedural errors was compiled and twelve vascular experts graded each error for the potential to disrupt procedural flow and cause harm. Using this multimodal approach, the Imperial College Error CAPture (ICECAP) tool was developed. The tool was validated during 21 consecutive arterial cases (52 h operating-time) as an observer-led error capture record and as a prompt for surgical teams to determine the feasibility of error self-reporting. RESULTS: Six primary categories (communication, equipment, procedure independent pressures, technical, safety awareness and patient related) and 20 error sub-categories were determined as the most frequent and important vascular procedural errors. Using the ICECAP, the number of errors detected correlated well between two observers (Spearman rho = 0.984, p < 0.001). Both observers identified all moderate or severe errors similarly and categorised all but 4/139 (2.9%) of the total errors in an identical fashion. Self-reporting of errors without prompting identified a mean of 24.4% (range 0-50%) of all recorded errors, whereas surgical teams reported a mean of 69.7% (range 50-100%) of errors when ICECAP error-category prompts were used. CONCLUSION: The ICECAP tool may be useful for capturing and categorising errors that occur during vascular/endovascular procedures. ICECAP may also have a role as an error recall prompt for self-reporting purposes by vascular surgical teams.

Advantages and limitations of robotic endovacular catheters for carotid artery stenting.

Carotid artery stenting (CAS) is an important development in the treatment of carotid artery stenosis and prevention of stroke. However, despite advances in technology, including embolic protection devices (EDPs), there are concerns that the embolic stroke risk is still too high in many reports, including a number of randomized controlled trials. Robotic technology has the potential to reduce the embolic risk by facilitating accurate and safe navigation to place sheaths in the common carotid artery, reducing the embolic load during this phase of the procedure prior to EDP placement. This paper identifies the embolic risk associated with different phases of the CAS procedure and predisposing factors that are primarily implicated in increased embolic load from a literature review. The potential for robotic technology to reduce risk in CAS is discussed using preclinical and experimental studies.