Cold Endoscopic Mucosal Resection (c-EMR) of Nonpedunculated Colorectal Polyps ≥20 mm: A Systematic Review and Meta-analysis.

BACKGROUND: There is increasing evidence that cold endoscopic mucosal resection (c-EMR) can effectively treat large colorectal polyps. We aim to appraise the current literature and evaluate outcomes following c-EMR for nonpedunculated colonic polyps ≥20 mm. METHODS: Major databases were searched. Primary outcomes included recurrence rate and adverse events. Meta-analysis was performed using a random-effects model. RESULTS: Nine articles were included in the final analysis, which included 817 patients and 1077 colorectal polyps. Average polyp size was 28.8 (±5.1) mm. The pooled recurrence rate of polyps of any histology at 4 to 6 months was 21.0% (95% CI: 9.0%-32.0%, P <0.001, I2 =97.3, P <0.001). Subgroup analysis showed that recurrence was 10% for proximal lesions (95% CI: 0.0%-20.0%, P =0.054, I2 =93.7%, P =0.054) and 9% for distal lesions (95% CI: 2.0%-21.0%, P =0.114, I2 =95.8%, P =0.114). Furthermore, subgroup analysis showed that recurrence was 12% for adenoma (95% CI: 4.0%-19.0%, P =0.003, I2 =98.0%, P =0.003), and 3% for sessile serrated polyps (95% CI: 1.0%-5.0%, P =0.002, I2 =34.4%, P =0.002). Post-polypectomy bleeding occurred in 1% (n=8/817) of patients, whereas abdominal pain occurred in 0.2% (n=2/817) of patients. CONCLUSIONS: C-EMR for nonpedunculated colorectal polyps ≥20 mm shows an excellent safety profile with a very low rate of delayed bleeding as well as significantly less recurrence for sessile serrated polyps than adenomas.

Endoscopic Management of Ampullary Adenomas in Familial Adenomatous Polyposis Syndrome: A Systematic Review with Pooled Analysis.

BACKGROUND: Endoscopic papillectomy is a viable therapy in ampullary lesions. Prior studies have reported on outcomes of sporadic ampullary lesions, and only small cohort studies have reported outcomes associated with familial adenomatous polyposis (FAP) syndrome. AIMS: We performed a systematic review with pooled analysis to assess the safety and efficacy of EP for treating ampullary adenomas in FAP. METHODS: We performed a comprehensive literature search of major databases from inception to May 2020. Studies that included patients with endoscopically resected ampullary lesions and FAP were eligible. The rate of technical success, en bloc resection, piecemeal resection, recurrence, and adverse events was pooled by means of a random-effects model to obtain a proportion with a 95% confidence interval (CI). RESULTS: Six studies, including a total of 99 patients, were included in our final analysis. Patient age ranged from 28 to 91 years. Pooled technical success was 90.3% (CI 76.9-96.3%, I2 = 31%). Rate of en bloc resection was 60.6% (CI 47.9-72.0%, I2 = 0%). Recurrence rate was 25.4% (5.7-65.9%, I2 = 82%). The post-procedural pancreatitis rate was 14.7% of which 68% (51 of 75) utilized prophylactic pancreatic stenting. Other adverse events included bleeding (9.2%) and perforation (4%). CONCLUSION: Endoscopic papillectomy offers high technical success but remains challenging in patients with FAP, particularly due to high recurrence rates.

Influence of the Elipse Intragastric Balloon on Obesity and Metabolic Profile: A Systematic Review and Meta-Analysis.

BACKGROUND: Intragastric balloons (IGBs) have been used to bridge the obesity treatment gap with the benefits of being minimally invasive but still required endoscopy. The Elipse IGB is a swallowable balloon that is spontaneously excreted at ∼16 weeks. However, studies are limited by small sample sizes. The authors aim to assess clinically relevant endpoints, namely weight loss outcomes, metabolic profile, balloon tolerability, and adverse events. METHODS: A literature search was performed from several databases from inception to July 2020. The pooled means and proportions of our data were analyzed using a random effects model. RESULTS: Seven studies involving 2152 patients met our eligibility criteria and were included. The mean baseline body mass index ranged from 32.1 to 38.6. The pooled mean difference (MD) in body mass index was 0.88 [confidence interval (CI): 0.58-1.18, I2=98%]. Total body weight loss was 12% (CI: 10.1-14.3, I2=94%) and excess body weight loss was 49.1% (CI: 30.6-67.5, I2=97%). The MD in waist circumference was 0.89 (CI: 0.72-1.05, I2=53%). MD in triglyceride level was 0.66 (CI: 0.21-1.1, I2=96%). Pooled early deflation rate was 1.8% (CI: 0.6-5.1, I2=74%). Our study also showed that the Elipse balloon was associated with less adverse events when compared with other IGBs. CONCLUSIONS: This meta-analysis demonstrates that the Elipse intragastric balloon is a safe, effective, and tolerable device for weight loss and obesity with a minimal side effect profile.

A stereotaxic breed-averaged, symmetric T2w canine brain atlas including detailed morphological and volumetrical data sets.

Stereotaxic systems and automatic tissue segmentation routines enable neuronavigation as well as reproducible processing of neuroimage datasets. Such systems have been developed for humans, non-human-primates, sheep, and rodents, but not for dogs. Although dogs share important neurofunctional and -anatomical features with humans, and in spite of their importance in translational neuroscience, little is known about the variability of the canine brain morphology and, possibly related, function. Moreover, we lack templates, tissue probability maps (TPM), and stereotaxic brain labels for implementation in standard software utilities such as Statistical Parametric Mapping (SPM). Hence, objective and reproducible, image-based investigations are currently impeded in dogs. We have created a detailed stereotaxic reference frame for dogs including TPM and tissue labels, enabling inter-individual and cross-study neuroimage analysis. T2w datasets were acquired from 16 neurologically inconspicuous dogs of different breeds by 3T MRI. The datasets were averaged after initial preprocessing using linear and nonlinear registration algorithms as implemented in SPM8. TPM for gray (GM) and white matter (WM) as well as cerebrospinal fluid (CSF) were created. Different cortical, subcortical, medullary, and CSF regions were manually labeled to create a spatial binary atlas being aligned with the template. A proof-of-concept for automatic determination of morphological and volumetrical characteristics was performed using additional canine datasets (n = 64) including a subgroup of laboratory beagles (n = 24). Overall, 21 brain regions were labeled using the segmented tissue classes of the brain template. The proof-of-concept trial revealed excellent suitability of the created tools for image processing and subsequent analysis. There was high intra-breed variability in frontal lobe and hippocampus volumes, and noticeable inter-breed corpus callosum volume variation. The T2w brain template provides important, breed-averaged canine brain anatomy features in a spatial standard coordinate system. TPM allows automatic tissue segmentation using SPM and enables unbiased automatic image processing or morphological characterization in different canine breeds. The reported volumetric and morphometric results may serve as a starting point for further research aimed at in vivo analysis of canine brain anatomy and function.

Shear-Activated Nanoparticle Aggregates Combined With Temporary Endovascular Bypass to Treat Large Vessel Occlusion.

BACKGROUND AND PURPOSE: The goal of this study is to combine temporary endovascular bypass (TEB) with a novel shear-activated nanotherapeutic (SA-NT) that releases recombinant tissue-type plasminogen activator (r-tPA) when exposed to high levels of hemodynamic stress and to determine if this approach can be used to concentrate r-tPA at occlusion sites based on high shear stresses created by stent placement. METHODS: A rabbit model of carotid vessel occlusion was used to test the hypothesis that SA-NT treatment coupled with TEB provides high recanalization rates while reducing vascular injury. We evaluated angiographic recanalization with TEB alone, intra-arterial delivery of soluble r-tPA alone, or TEB combined with 2 doses of intra-arterial infusion of either the SA-NT or soluble r-tPA. Vascular injury was compared against stent-retriever thrombectomy. RESULTS: Shear-targeted delivery of r-tPA using the SA-NT resulted in the highest rate of complete recanalization when compared with controls (P=0.0011). SA-NT (20 mg) had a higher likelihood of obtaining complete recanalization as compared with TEB alone (odds ratio 65.019, 95% confidence interval 1.77, >1000; P=0.0231), intra-arterial r-tPA alone (odds ratio 65.019, 95% confidence interval 1.77, >1000; P=0.0231), or TEB with soluble r-tPA (2 mg; odds ratio 18.78, 95% confidence interval 1.28, 275.05; P=0.0322). Histological analysis showed circumferential loss of endothelium restricted to the area where the TEB was deployed; however, there was significantly less vascular injury using a TEB as compared with stent-retriever procedure (odds ratio 12.97, 95% confidence interval 8.01, 21.02; P<0.0001). CONCLUSIONS: A novel intra-arterial, nanoparticle-based thrombolytic therapy combined with TEB achieves high rates of complete recanalization. Moreover, this approach reduces vascular trauma as compared with stent-retriever thrombectomy.

Comparison of left versus right lateral starting position on colonoscopy: a systematic review and meta-analysis of randomized controlled trials.

BACKGROUND: Modifying patient position during colonoscopy has been proposed as a simple and inexpensive technique to increase luminal distention and improve navigation through the large bowel. The left lateral (LL) decubitus starting position is commonly used during colonoscopy. However, reports indicate that other starting positions may offer additional benefit. We aimed to determine if the right lateral (RL) starting position compared to the standard LL starting position could improve outcomes in colonoscopy. METHODS: We searched PubMed, Medline, and EMBASE through June 2020 to identify studies comparing RL and LL starting positions during colonoscopy. The primary outcomes included mean cecal insertion time and cecal intubation rate, and adverse events were assessed by pooling data using a random-effects model expressed in terms of odds ratio (OR), mean difference, and 95% confidence interval (CI). RESULTS: We identified 5 randomized controlled trials, including 809 participants, that compared LL vs. RL colonoscopy. The pooled OR for cecal intubation rate was 1.3 (95%CI 0.8-2.3; P=0.3). The mean difference in mean cecal insertion time was 0.08 (95%CI -0.09 to 0.26; P=0.4). Heterogeneity between studies was low (I 2=0%). No complications were reported in either arm of the study. Pain scores assessed using a visual analog scale were comparable among both arms of the study. CONCLUSION: The RL starting position for colonoscopy was comparable to the LL and offered no additional benefit in terms of cecal intubation time, intubation rate, or patient discomfort.

Wet- versus dry-suction techniques for EUS-FNA of solid lesions: A systematic review and meta-analysis.

The optimal sampling techniques for EUS-FNA remain unclear and have not been standardized. To improve diagnostic accuracy, suction techniques for EUS-FNA have been developed and are widely used among endoscopists. The aim of this study was to compare wet-suction and dry-suction EUS-FNA techniques for sampling solid lesions. We performed a comprehensive literature search of major databases (from inception to June 2020) to identify prospective studies comparing wet-suction EUS-FNA and dry-suction EUS-FNA. Specimen adequacy, sample contamination, and histologic accuracy were assessed by pooling data using a random-effects model expressed in terms of odds ratio (OR) and 95% confidence interval (CI). Six studies including a total of 418 patients (365 wet suction vs. 377 dry suction) were included in our final analysis. The study included a total of 535 lesions (332 pancreatic lesions and 203 nonpancreatic lesions). The pooled odds of sample adequacy was 3.18 (CI: 1.82-5.54, P = 0.001) comparing wet- and dry-suction cohorts. The pooled odds of blood contamination was 1.18 (CI: 0.75-1.86, P = 0.1). The pooled rate for blood contamination was 58.33% (CI: 53.65%-62.90%) in the wet-suction cohort and 54.60% (CI 49.90%- 59.24%) in the dry-suction cohort (P = 0.256). The pooled odds of histological diagnosis was 3.68 (CI 0.82-16.42, P = 0.1). Very few adverse events were observed and did not have an impact on patient outcomes using either method. EUS-FNA using the wet-suction technique offers higher specimen quality through comparable rates of blood contamination and histological accuracy compared to dry-suction EUS-FNA.

Infarct Evolution in a Large Animal Model of Middle Cerebral Artery Occlusion.

Mechanical thrombectomy for the treatment of ischemic stroke shows high rates of recanalization; however, some patients still have a poor clinical outcome. A proposed reason for this relates to the fact that the ischemic infarct growth differs significantly between patients. While some patients demonstrate rapid evolution of their infarct core (fast evolvers), others have substantial potentially salvageable penumbral tissue even hours after initial vessel occlusion (slow evolvers). We show that the dog middle cerebral artery occlusion model recapitulates this key aspect of human stroke rendering it a highly desirable model to develop novel multimodal treatments to improve clinical outcomes. Moreover, this model is well suited to develop novel image analysis techniques that allow for improved lesion evolution prediction; we provide proof-of-concept that MRI perfusion-based time-to-peak maps can be utilized to predict the rate of infarct growth as validated by apparent diffusion coefficient-derived lesion maps allowing reliable classification of dogs into fast versus slow evolvers enabling more robust study design for interventional research.

A canine model of mechanical thrombectomy in stroke.

PURPOSE: To develop a preclinical model of stroke with a large vessel occlusion treated with mechanical thrombectomy. MATERIALS AND METHODS: An ischemic stroke model was created in dogs by the introduction of an autologous clot into the middle cerebral artery (MCA). A microcatheter was navigated to the clot and a stent retriever thrombectomy was performed with the goal to achieve Thrombolysis in Cerebral Ischemia (TICI) 2b/3 reperfusion. Perfusion and diffusion MRI was acquired after clot placement and following thrombectomy to monitor the progression of restricted diffusion as well as changes in ischemia as a result of mechanical thrombectomy. Post-mortem histology was done to confirm MCA territory infarct volume. RESULTS: Initial MCA occlusion with TICI 0 flow was documented in all six hound-cross dogs entered into the study. TICI 2b/3 revascularization was achieved with one thrombectomy pass in four of six animals (67%). Intra-procedural events including clot autolysis leading to spontaneous revascularization (n=1) and unresolved vasospasm (n=1) accounted for thrombectomy failure. In one case, iatrogenic trauma during microcatheter navigation resulted in a direct arteriovenous fistula at the level of the cavernous carotid. Analysis of MRI indicated that a volume of tissue from the initial perfusion deficit was spared with reperfusion following thrombectomy, and there was also a volume of tissue that infarcted between MRI and ultimate recanalization. CONCLUSION: We describe a large animal stroke model in which mechanical thrombectomy can be performed. This model may facilitate, in a preclinical setting, optimization of complex multimodal stroke treatment paradigms for clinical translation.

Robotic Assisted MRI-Guided Interventional Interstitial MR-Guided Focused Ultrasound Ablation in a Swine Model.

BACKGROUND: Ablative lesions are current treatments for epilepsy and brain tumors. Interstitial magnetic resonance (MR) guided focused ultrasound (iMRgFUS) may be an alternate ablation technique which limits thermal tissue charring as compared to laser therapy (LITT) and can produce larger ablation patterns nearer the surface than transcranial MR guided focused ultrasound (tcMRgFUS). OBJECTIVE: To describe our experience with interstitial focused ultrasound (iFUS) ablations in swine, using MR-guided robotically assisted (MRgRA) delivery. METHODS: In an initial 3 animals, we optimized the workflow of the robot in the MR suite and made modifications to the robotic arm to allow range of motion. Then, 6 farm pigs (4 acute, 2 survival) underwent 7 iMRgFUS ablations using MRgRA. We altered dosing to explore differences between thermal dosing in brain as compared to other tissues. Imaging was compared to gross examination. RESULTS: Our work culminated in adjustments to the MRgRA, iMRgFUS probes, and dosing, culminating in 2 survival surgeries; swine had ablations with no neurological sequelae at 2 wk postprocedure. Immediately following iMRgFUS therapy, diffusion-weighted imaging, and T1 weighted MR were accurate reflections of the ablation volume. T2 and fluid-attenuated inversion-recovery (FLAIR) images were accurate reflections of ablation volume 1-wk postprocedure. CONCLUSION: We successfully performed MRgRA iFUS ablation in swine and found intraoperative and postoperative imaging to correlate with histological examination. These data are useful to validate our system and to guide imaging follow-up for thermal ablation lesions in brain tissue from our therapy, tcMRgFUS, and LITT.

Acute thrombus formation on phosphorilcholine surface modified flow diverters.

PURPOSE: Thromboembolic complications remain a limitation of flow diverting stents. We hypothesize that phosphorilcholine surface modified flow diverters (Pipeline Flex with Shield Technology, sPED) would have less acute thrombus formation on the device surface compared with the classic Pipeline Embolization device (cPED). METHODS: Elastase-induced aneurysms were created in 40 rabbits and randomly assigned to receive cPED or sPED devices with and without dual antiplatelet therapy (DAPT) (four groups, n=10/group). Angioplasty was performed to enhance apposition and create intimal injury for a pro-thrombotic environment. Both before and after angioplasty, the flow diverter was imaged with intravascular optical coherence tomography. The outcome measure was the number of predefined segments along the implant relative to the location of the aneurysm with a minimum of 0 (no clot formation) and maximum of 3 (all segments with thrombus). Clot formation over the device at ostia of branch arteries was assessed as either present or absent. RESULTS: Following angioplasty, the number of flow diverter segments with clots was significantly associated with the flow diverter (p<0.0001), but not with DAPT (p=0.3872) or aneurysm neck size (p=0.8555). The incidence rate for clots with cPED was 1.72 times more than with sPED. The clots on the flow diverter at the location corresponding to side branch ostia was significantly lower with sPED than with cPED (OR 0.180; 95% CI 0.044 to 0.734; p=0.0168), but was not associated with DAPT (p=0.3198). CONCLUSION: In the rabbit model, phosphorilcholine surface modified flow diverters are associated with less thrombus formation on the surface of the device.

Communicating malapposition of flow diverters assessed with optical coherence tomography correlates with delayed aneurysm occlusion.

BACKGROUND: Optical coherence tomography (OCT) is a high resolution intravascular imaging method that allows visualization of flow diverter struts and the vessel wall. In this study, malapposition of the flow diverter that continues into the neck of the aneurysm, named communicating malapposition (CM), was investigated as a potential factor for delayed aneurysm healing. METHODS: 40 New Zealand White rabbits underwent elastase induced aneurysm creation, and were subsequently assigned to one of four treatment groups based on flow diverter type and administration of antiplatelet therapy. All animals underwent post device deployment balloon angioplasty and subsequent OCT to assess device/vessel apposition. The incidence of CM seen on OCT was assessed with a binary scoring system: 0-CM present; 1-CM absent. At 30 days, DSA was acquired to assess aneurysm healing. Aneurysm healing on terminal DSA was measured using a previously developed 5 point scale, with a score of 3 or 4 considered a positive outcome. RESULTS: All animals were grouped into a single cohort for analysis as no difference in the rate of CM or healing was seen in the four treatment groups. Significant interaction between the absence of CM and a positive outcome was confirmed by Fisher exact test (P=0.0034). Angioplasty was shown to treat 33% of the cases of CM seen at implant, and these treated cases overwhelmingly had a positive outcome (P<0.001). CONCLUSION: The use of OCT to assess CM of flow diverters has been shown to be predictive of the 30 day healing rate of an animal model of aneurysms.

Phosphorylcholine surface modified flow diverter associated with reduced intimal hyperplasia.

BACKGROUND: Optical coherence tomography (OCT) is a high-resolution, intra-vascular diagnostic technique widely used for the characterization of vascular pathologies and optimization of stent implantation during percutaneous coronary intervention. OCT was used to investigate the in vivo vascular response to a new phosphorylcholine surface modified flow diverter (sPED). METHODS: In an in vivo rabbit aneurysmal model, we used two different types of flow diverters (classic Pipeline - cPED; and sPED) with or without dual antiplatelet therapy (four groups, n=10 per group). OCT cross-sectional area measurements were compared with histology in all animals. Neointimal hyperplasia (NIH) ratio was compared between OCT and histology at five different levels for each stent. The severity of NIH was also compared between the different stents, antiplatelet protocols, and vessel locations. RESULTS: OCT was used to calculate in-stent hyperplasia in 227 different locations corresponding to histology sections. OCT measurement strongly correlated with gold standard histology (r2=0.83; slope=0.988; P<0.0001). sPED had significantly less in-stent NIH than non-treated flow diverters (mean percent of lumen reduction 5.7% for sPED versus 8.9% for cPED; P<0.0001). The NIH ratio was slightly higher with dual antiplatelet therapy (DAPT) (NIH ratio=7.9% with DAPT versus 6.8% without DAPT; P<0.05). Complete and near complete occlusion rates of the aneurysms were not different with the cPED or sPED. CONCLUSION: OCT is a promising technique for immediate and long-term evaluation of flow diverter stent treatments. In an animal model, phosphorylcholine surface modified flow diverters induces less NIH after stent implant without reducing aneurysm occlusion rates.

Development of a high resolution MRI intracranial atherosclerosis imaging phantom.

BACKGROUND AND PURPOSE: Currently, there is neither a standard protocol for vessel wall MR imaging of intracranial atherosclerotic disease (ICAD) nor a gold standard phantom to compare MR sequences. In this study, a plaque phantom is developed and characterized that provides a platform for establishing a uniform imaging approach for ICAD. MATERIALS AND METHODS: A patient specific injection mold was 3D printed to construct a geometrically accurate ICAD phantom. Polyvinyl alcohol hydrogel was infused into the core shell mold to form the stenotic artery. The ICAD phantom incorporated materials mimicking a stenotic vessel and plaque components, including fibrous cap and lipid core. Two phantoms were scanned using high resolution cone beam CT and compared with four different 3 T MRI systems across eight different sites over a period of 18 months. Inter-phantom variability was assessed by lumen dimensions and contrast to noise ratio (CNR). RESULTS: Quantitative evaluation of the minimum lumen radius in the stenosis showed that the radius was on average 0.80 mm (95% CI 0.77 to 0.82 mm) in model 1 and 0.77 mm (95% CI 0.74 to 0.81 mm) in model 2. The highest CNRs were observed for comparisons between lipid and vessel wall. To evaluate manufacturing reproducibility, the CNR variability between the two models had an average absolute difference of 4.31 (95% CI 3.82 to 5.78). Variation in CNR between the images from the same scanner separated by 7 months was 2.5-6.2, showing reproducible phantom durability. CONCLUSIONS: A plaque phantom composed of a stenotic vessel wall and plaque components was successfully constructed for multicenter high resolution MRI standardization.

Novel Distal Emboli Protection Technology: The EmboTrap.

BACKGROUND: Over the course of the thrombectomy procedure, clot fragments may become dislodged and lead to downstream emboli due to manipulation of an endovascular device. The EmboTrap thrombectomy system features an inner stent channel with an outer stent trap design that may potentially reduce the risk of distal clot fragmentation during clot removal. We tested the hypothesis that distal emboli to both the same and new territory generated during mechanical thrombectomy are a function of device design. METHODS: EmboTrap and Solitaire thrombectomy were conducted in an in vitro model system that mimicked a middle-cerebral artery (MCA) occlusion within a complete circle of Willis vascular replica and a contrast-enhanced clot analog. Emboli generated during the procedure with a size >1,000 µm were collected and measured with calipers. The Coulter principle was used to characterize emboli with a size between 200 and 1,000 µm. RESULTS: EmboTrap thrombectomy resulted in a significant reduction in the risk of large emboli (>1,000 µm) formation as compared to first-generation stent retriever thrombectomy (p = 0.031, Fisher exact test). The majority of emboli >1,000 µm (∼80%) were found in the MCA, regardless of device type. There was no significant difference between the EmboTrap and Solitaire in 200 to 1,000 µm emboli formation (p = 0.89, Mann-Whitney test). When combining all emboli in the most dangerous range (>200 µm), EmboTrap offered a size reduction of emboli (p = 0.022). CONCLUSION: The risk of distal embolization can be altered with improved stent retriever design. When encountering fragment-prone clots, EmboTrap thrombectomy may lower the risk of distal embolization.

Grading of Regional Apposition after Flow-Diverter Treatment (GRAFT): a comparative evaluation of VasoCT and intravascular OCT.

BACKGROUND: Poor vessel wall apposition of flow diverter (FD) stents poses risks for stroke-related complications when treating intracranial aneurysms, necessitating long-term surveillance imaging. To facilitate quantitative evaluation of deployed devices, a novel algorithm is presented that generates intuitive two-dimensional representations of wall apposition from either high-resolution contrast-enhanced cone-beam CT (VasoCT) or intravascular optical coherence tomography (OCT) images. METHODS: VasoCT and OCT images were obtained after FD implant (n=8 aneurysms) in an experimental sidewall aneurysm model in canines. Surface models of the vessel wall and FD device were extracted, and the distance between them was presented on a two-dimensional flattened map. Maps and cross-sections at potential locations of malapposition detected on VasoCT-based maps were compared. The performance of OCT-based apposition detection was evaluated on manually labeled cross-sections using logistic regression against a thresholded (≥0.25 mm) apposition measure. RESULTS: VasoCT and OCT acquisitions yielded similar Grading of Regional Apposition after Flow-Diverter Treatment (GRAFT) apposition maps. GRAFT maps from VasoCT highlighted 16 potential locations of malapposition, of which two were found to represent malapposed device struts. Logistic regression showed that OCT could detect malapposition with a sensitivity of 98% and a specificity of 81%. CONCLUSIONS: GRAFT delivered quantitative and visually convenient representations of potential FD malapposition and occasional acute thrombus formation. A powerful combination for future neuroendovascular applications is foreseen with the superior resolution delivered by intravascular OCT.

Quantitative assessment of device-clot interaction for stent retriever thrombectomy.

PURPOSE: Rapid revascularization in emergent large vessel occlusion with endovascular embolectomy has proven clinical benefit. We sought to measure device-clot interaction as a potential mechanism for efficient embolectomy. METHODS: Two different radiopaque clot models were injected to create a middle cerebral artery occlusion in a patient-specific vascular phantom. A radiopaque stent retriever was deployed within the clot by unsheathing the device or a combination of unsheathing followed by pushing the device (n=8/group). High-resolution cone beam CT was performed immediately after device deployment and repeated after 5 min. An image processing pipeline was created to quantitatively evaluate the volume of clot that integrates with the stent, termed the clot integration factor (CIF). RESULTS: The CIF was significantly different for the two deployment variations when the device engaged the hard clot (p=0.041), but not the soft clot (p=0.764). In the hard clot, CIF increased significantly between post-deployment and final imaging datasets when using the pushing technique (p=0.019), but not when using the unsheathing technique (p=0.067). When we investigated the effect of time on CIF in the different clot models disregarding the technique, the CIF was significantly increased in the final dataset relative to the post-deployment dataset in both clot models (p=0.004-0.007). CONCLUSIONS: This study demonstrates in an in vitro system the benefit of pushing the Trevo stent during device delivery in hard clot to enhance integration. Regardless of delivery technique, clot-device integration increased in both clot models by waiting 5 min.