Cerebral Aneurysm Occlusion at 12-Month Follow-Up After Flow-Diverter Treatment: Statistical Modeling for V&V With Real-World Data.

Background: Flow-Diverter (FD) porosity has been pointed as a critical factor in the occlusion of cerebral aneurysms after treatment. Objective: Verification and Validation of computational models in terms of predictive capacity, relating FD porosity and occlusion after cerebral aneurysms treatment. Methods: Sixty-four aneurysms, with pre-treatment and follow-up images, were considered. Patient demographics and aneurysm morphological information were collected. The computational simulation provided by ANKYRAS provided FD porosity, expansion, and mesh angle. FD occlusion was assessed and recorded from follow-up images. Multiple regression Logit and analysis of covariance (ANCOVA) models were used to model the data with both categorical and continuous models. Results: Occlusion of the aneurysm after 12 months was affected by aneurysm morphology but not by FD mesh morphology. A Time-To-Occlusion (TTO) of 6.92 months on average was observed with an SE of 0.24 months in the aneurysm population surveyed. TTO was estimated with statistical significance from the resulting model for the data examined and was capable of explaining 92% of the data variation. Conclusions: Porosity was found to have the most correction power when assessing TTO, proving its importance in the process of aneurysm occlusion. Still, further Verification and Validation (V&V) of treatment simulation in more extensive, multi-center, and randomized databases is required.

Endovascular treatment of intracraneal aneurysm with pipeline embolization device: experience in four centres in Barcelona.

UNLABELLED: Flow diverters represent a useful tool in the treatment of fusiform aneurysms and wide-neck saccular aneurysms which until the advent of this technology were problematic to treat. Pipeline™ Embolization Device (PED) has been described in several series showing high rates of occlusion and being relatively safe. OBJECTIVE: Shows the experience in four different neurointerventional centres in Barcelona with the PED (Covidien) between February 2010 and October 2013. METHODS: We reviewed retrospectively patients treated with PED in four neurointerventional centres in Barcelona between February 2010 and October 2013. RESULTS: Forty-two patients (89.4%) with non-ruptured aneurysms and five (10.6%) post-SAH were treated, with a mean age of 51 years (range 26-76). We treated 67 aneurysms with a mean of 1.4 1-3 PED per patient. We have no mortality and three post-procedural complications with clinical consequences, two of them severe with intracranial haemorrhage and the other with anterior choroidal artery thrombosis. Follow-up was in 45 patients (65 aneurysm) achieving complete occlusion in 90.8% at 12 months of follow-up. Two aneurysms which remained without any changes were distal and fusiform including main bifurcations (3.1%). CONCLUSION: Treatment by PED of fusiform or wide-neck saccular aneurysms is associated with high rates of occlusion after six and 12 months. Correct selection of the patients, aneurysms and also specific characteristics of the Pipeline device should be known in order to select the best therapeutic option. Our findings suggest that the indication must be judged case by case in the selection of suitable patients for PED therapy.

Computation of the change in length of a braided device when deployed in realistic vessel models.

PURPOSE: An important issue in the deployment of braided stents, such as flow diverters, is the change in length, also known as foreshortening, underwent by the device when is released from the catheter into a blood vessel. The position of the distal end is controlled by the interventionist, but knowing a priori the position of the proximal end of the device is not trivial. In this work, we assess and validate a novel computer method to predict the length that a braided stent will adopt inside a silicon model of an anatomically accurate vessel. METHODS: Three-dimensional rotational angiography images of aneurysmatic patients were used to generate surface models of the vessels (3D meshes) and then create accurate silicon models from them. A braided stent was deployed into each silicon model to measure its length. The same stents deployed on the silicon models were virtually deployed on the 3D meshes using the method being evaluated. RESULTS: The method was applied to five stent placements on three different silicon models. The length adopted by the real braided device in the silicon models varies between 15 and 30% from the stent length specified by the manufacturer. The final length predicted by the method was within the estimated error of the measured real stent length. CONCLUSIONS: The method provides, in a few seconds, the length of a braided stent deployed inside a vessel, showing an accurate estimation of the final length for the cases studied. This technique could provide useful information for planning the intervention and improve endovascular treatment of intracranial aneurysms in the future.

Outcomes of a contemporary cohort of 536 consecutive patients with acute ischemic stroke treated with endovascular therapy.

BACKGROUND AND PURPOSE: We sought to assess outcomes after endovascular treatment/therapy of acute ischemic stroke, overall and by subgroups, and looked for predictors of outcome. METHODS: We used data from a mandatory, population-based registry that includes external monitoring of completeness, which assesses reperfusion therapies for consecutive patients with acute ischemic stroke since 2011. We described outcomes overall and by subgroups (age ≤ or >80 years; onset-to-groin puncture ≤ or >6 hours; anterior or posterior strokes; previous IV recombinant tissue-type plasminogen activator or isolated endovascular treatment/therapy; revascularization or no revascularization), and determined independent predictors of good outcome (modified Rankin Scale score ≤2) and mortality at 3 months by multivariate modeling. RESULTS: We analyzed 536 patients, of whom 285 received previous IV recombinant tissue-type plasminogen activator. Overall, revascularization (modified Thrombolysis In Cerebral Infarction scores, 2b and 3) occurred in 73.9%, 5.6% developed symptomatic intracerebral hemorrhages, 43.3% achieved good functional outcome, and 22.2% were dead at 90 days. Adjusted comparisons by subgroups systematically favored revascularization (lower proportion of symptomatic intracerebral hemorrhages and death rates and higher proportion of good outcome). Multivariate analyses confirmed the independent protective effect of revascularization. Additionally, age >80 years, stroke severity, hypertension (deleterious), atrial fibrillation, and onset-to-groin puncture ≤6 hours (protective) also predicted good outcome, whereas lack of previous disability and anterior circulation strokes (protective) as well as and hypertension (deleterious) independently predicted mortality. CONCLUSIONS: This study reinforces the role of revascularization and time to treatment to achieve enhanced functional outcomes and identifies other clinical features that independently predict good/fatal outcome after endovascular treatment/therapy.

Neurothrombectomy for the treatment of acute ischemic stroke: results from the TREVO study.

BACKGROUND: Fast recanalization has been shown to be one of the most important factors for good clinical outcome in stroke patients with acute large vessel occlusion. While intravenous thrombolysis has been shown to be of limited effect in patients with large clot burden, intra-arterial neurothrombectomy offers a new and promising possibility to achieve high recanalization rates within a short time. The Trevo device is a stent-like retriever and was primarily designed to remove thrombus in patients experiencing an acute ischemic stroke. We report on the results of the TREVO Study, which was a prospective, multicenter study in acute stroke patients treated with the Trevo device. METHODS: Patients were recruited in seven European centers under the control of an external monitor. Centers were selected because of their long experience with interventional stroke therapy especially with neurothrombectomy. We included adults aged 18-85 years with angiographically confirmed large vessel occlusion strokes and NIHSS scores of 8-30 and treatable within 8 h of symptom onset. The primary endpoint was revascularization, defined as at least TICI (thrombolysis in cerebral infarction) 2a. The revascularization scores were assessed by an independent core lab. Secondary endpoints were clinical outcome at 90 days (mRS 90), any device-related serious adverse events and the rate of symptomatic intracerebral hemorrhages. RESULTS: 60 patients were enrolled. The overall recanalization rate (≥TICI 2a) was 91.7% and TICI 2b and 3 was achieved in 78.3%. At 90 days, 55% of the patients had a favorable neurological outcome (mRS 0-2) and 20% had died. Patients with successful recanalization (TICI 2a,b/3) had a good 90-day neurological outcome (mRS 0-2) in 60%, whereas no patient without recanalization had a mRS 90 <3. The overall rate of symptomatic intracerebral hemorrhage according to the SITS-MOST criteria was 5% (3/60). CONCLUSIONS: The study suggest that the Trevo Stentriever™ is a safe and effective device, which may offer the possibility of a high reperfusion rate and a high rate of patients with good clinical outcome after acute ischemic stroke due to proximal arterial occlusion. Randomized trials comparing intravenous thrombolysis with neurothrombectomy are now urgently needed to evaluate this new approach of interventional stroke therapy.

Risk factors for the development of vertebral fractures after percutaneous vertebroplasty.

We have recently observed an increased risk for vertebral fractures (VF) in a randomized controlled trial comparing the analgesic effect of vertebroplasty (VP) versus conservative treatment in symptomatic VF. The aim of the present study was to evaluate the risk factors related to the development of VF after VP in these patients. We evaluated risk factors including age, gender, bone mineral density, the number, type, and severity of vertebral deformities at baseline, the number of vertebral bodies treated, the presence and location of disk cement leakage, bone remodeling (determining bone turnover markers) and 25 hydroxyvitamin D [25(OH)D] levels at baseline in all patients. Twenty-nine radiologically new VF were observed in 17 of 57 patients undergoing VP, 72% adjacent to the VP. Patients developing VF after VP showed an increased prevalence of 25(OH)D deficiency (<20 ng/mL) and higher P1NP values. The principal factor related to the development of VF after VP in multivariate analysis was 25(OH)D levels < 20 ng/mL (RR, 15.47; 95% CI, 2.99-79.86, p < 0.0001), whereas age >80 years (RR, 3.20; 95% CI, 1.70-6.03, p = 0.0007) and glucocorticoid therapy (RR, 3.64; 95% CI, 1.61-8.26, p = 0.0055) constituted the principal factors in the overall study population. Increased risk of VF after VP was also associated with cement leakage into the inferior disk (RR, 6.14; 95% CI, 1.65-22.78, p = 0.044) and more than one vertebral body treated during VP (RR, 4.19; 95% CI, 1.03-34.3, p = 0.044). In conclusion, nearly 30% of patients with osteoporotic VF treated with VP had a new VF after the procedure. Age, especially >80 years, the presence of inferior disk cement leakage after the procedure, the number of cemented vertebrae, and low 25(OH)D serum levels were related to the development of new VF in these patients, with the latter indicating the need to correct vitamin D deficiency prior to performing VP.

A virtual coiling technique for image-based aneurysm models by dynamic path planning.

Computational algorithms modeling the insertion of endovascular devices, such as coil or stents, have gained an increasing interest in recent years. This scientific enthusiasm is due to the potential impact that these techniques have to support clinicians by understanding the intravascular hemodynamics and predicting treatment outcomes. In this work, a virtual coiling technique for treating image-based aneurysm models is proposed. A dynamic path planning was used to mimic the structure and distribution of coils inside aneurysm cavities, and to reach high packing densities, which is desirable by clinicians when treating with coils. Several tests were done to evaluate the performance on idealized and image-based aneurysm models. The proposed technique was validated using clinical information of real coiled aneurysms. The virtual coiling technique reproduces the macroscopic behavior of inserted coils and properly captures the densities, shapes and coil distributions inside aneurysm cavities. A practical application was performed by assessing the local hemodynamic after coiling using computational fluid dynamics (CFD). Wall shear stress and intra-aneurysmal velocities were reduced after coiling. Additionally, CFD simulations show that coils decrease the amount of contrast entering the aneurysm and increase its residence time.

AngioLab--a software tool for morphological analysis and endovascular treatment planning of intracranial aneurysms.

Determining whether and how an intracranial aneurysm should be treated is a tough decision that clinicians face everyday. Emerging computational tools could help clinicians analyze clinical data and make these decisions. AngioLab is a single graphical user interface, developed on top of the open source framework GIMIAS, that integrates some of the latest image analysis and computational modeling tools for intracranial aneurysms. Two workflows are available: Advanced Morphological Analysis (AMA) and Endovascular Treatment Planning (ETP). AngioLab has been evaluated by a total of 62 clinicians, who considered the information provided by AngioLab relevant and meaningful. They acknowledged the emerging need of these type of tools and the potential impact they might have on the clinical decision-making process.

Virtual coiling of intracranial aneurysms based on dynamic path planning.

Coiling is possibly the most widespread endovascular treatment for intracranial aneurysms. It consists in the placement of metal wires inside the aneurysm to promote blood coagulation. This work presents a virtual coiling technique for pre-interventional planning and post-operative assessment of coil embolization procedure of aneurysms. The technique uses a dynamic path planning algorithm to mimic coil insertion inside a 3D aneurysm model, which allows to obtain a plausible distribution of coils within a patient-specific anatomy. The technique was tested on two idealized geometries: an sphere and a hexahedron. Subsequently, the proposed technique was applied in 10 realistic aneurysm geometries to show its reliability in anatomical models. The results of the technique was compared to digital substraction angiography images of two aneurysms.

Dynamic estimation of three-dimensional cerebrovascular deformation from rotational angiography.

PURPOSE: The objective of this study is to investigate the feasibility of detecting and quantifying 3D cerebrovascular wall motion from a single 3D rotational x-ray angiography (3DRA) acquisition within a clinically acceptable time and computing from the estimated motion field for the further biomechanical modeling of the cerebrovascular wall. METHODS: The whole motion cycle of the cerebral vasculature is modeled using a 4D B-spline transformation, which is estimated from a 4D to 2D + t image registration framework. The registration is performed by optimizing a single similarity metric between the entire 2D + t measured projection sequence and the corresponding forward projections of the deformed volume at their exact time instants. The joint use of two acceleration strategies, together with their implementation on graphics processing units, is also proposed so as to reach computation times close to clinical requirements. For further characterizing vessel wall properties, an approximation of the wall thickness changes is obtained through a strain calculation. RESULTS: Evaluation on in silico and in vitro pulsating phantom aneurysms demonstrated an accurate estimation of wall motion curves. In general, the error was below 10% of the maximum pulsation, even in the situation when substantial inhomogeneous intensity pattern was present. Experiments on in vivo data provided realistic aneurysm and vessel wall motion estimates, whereas in regions where motion was neither visible nor anatomically possible, no motion was detected. The use of the acceleration strategies enabled completing the estimation process for one entire cycle in 5-10 min without degrading the overall performance. The strain map extracted from our motion estimation provided a realistic deformation measure of the vessel wall. CONCLUSIONS: The authors' technique has demonstrated that it can provide accurate and robust 4D estimates of cerebrovascular wall motion within a clinically acceptable time, although it has to be applied to a larger patient population prior to possible wide application to routine endovascular procedures. In particular, for the first time, this feasibility study has shown that in vivo cerebrovascular motion can be obtained intraprocedurally from a 3DRA acquisition. Results have also shown the potential of performing strain analysis using this imaging modality, thus making possible for the future modeling of biomechanical properties of the vascular wall.

Automated segmentation of cerebral vasculature with aneurysms in 3DRA and TOF-MRA using geodesic active regions: an evaluation study.

PURPOSE: To evaluate the suitability of an improved version of an automatic segmentation method based on geodesic active regions (GAR) for segmenting cerebral vasculature with aneurysms from 3D x-ray reconstruction angiography (3DRA) and time of flight magnetic resonance angiography (TOF-MRA) images available in the clinical routine. METHODS: Three aspects of the GAR method have been improved: execution time, robustness to variability in imaging protocols, and robustness to variability in image spatial resolutions. The improved GAR was retrospectively evaluated on images from patients containing intracranial aneurysms in the area of the Circle of Willis and imaged with two modalities: 3DRA and TOF-MRA. Images were obtained from two clinical centers, each using different imaging equipment. Evaluation included qualitative and quantitative analyses of the segmentation results on 20 images from 10 patients. The gold standard was built from 660 cross-sections (33 per image) of vessels and aneurysms, manually measured by interventional neuroradiologists. GAR has also been compared to an interactive segmentation method: isointensity surface extraction (ISE). In addition, since patients had been imaged with the two modalities, we performed an intermodality agreement analysis with respect to both the manual measurements and each of the two segmentation methods. RESULTS: Both GAR and ISE differed from the gold standard within acceptable limits compared to the imaging resolution. GAR (ISE) had an average accuracy of 0.20 (0.24) mm for 3DRA and 0.27 (0.30) mm for TOF-MRA, and had a repeatability of 0.05 (0.20) mm. Compared to ISE, GAR had a lower qualitative error in the vessel region and a lower quantitative error in the aneurysm region. The repeatability of GAR was superior to manual measurements and ISE. The intermodality agreement was similar between GAR and the manual measurements. CONCLUSIONS: The improved GAR method outperformed ISE qualitatively as well as quantitatively and is suitable for segmenting 3DRA and TOF-MRA images from clinical routine.

Endovascular treatment of a giant intracranial aneurysm with a stent-graft.

This report describes a giant intracavernous carotid aneurysm successfully treated by the placement of a single covered stent. A 40-year-old woman was admitted with a progressive diplopia in relation with palsy of the IV and VI cranial nerves. Magnetic resonance imaging revealed an intracavernous giant aneurysm located at the bifurcation between the origin of a trigeminal artery and the intracavernous portion of the right internal carotid artery. A covered stent was successfully placed, and complete exclusion of the aneurysm was confirmed at 11-month follow-up angiography. The use of covered stents in intracranial vascular structures can now be a feasible way of treating selected cases of wide-necked intracranial aneurysms.

Leiomyosarcoma of sacrum: imaging and histopathologic findings.

A rare case of low-grade primary leiomyosarcoma of the sacrum is described in a young woman who suffered from pain in the right sacroiliac region. A lytic sacral mass was observed on conventional radiology and CT studies. Magnetic resonance imaging clearly showed Gd-DTPA enhancement in the entire mass demonstrating its hypervascularity, which was later confirmed by angiography. Histopathology and immunohistochemical results of biopsy and curettage of the lesion confirmed the diagnosis. We report on the features of a rare tumor entity through imaging and diagnostic methods.