Intracranial Dural Arteriovenous Fistulas.

Dural arteriovenous fistulas (DAVFs) are abnormal communications between meningeal arteries and dural venous sinuses and/or cortical veins. Although many fistulas are benign and do not require treatment, some may carry a significant risk of bleeding or cause symptoms and warrant treatment. This review provides a review of various aspects of intracranial DAVFs including epidemiology, pathophysiology, clinical presentation, imaging characteristics, classification, natural history, and management options. By exploring these topics, we aim to enhance understanding of this condition and facilitate patient care.

Pediatric Moyamoya Presenting as a Subarachnoid Hemorrhage from a Ruptured Anterior Cerebral Artery Aneurysm.

BACKGROUND: The incidence of Moyamoya disease (MMD)-associated intracranial aneurysms ranges from 3% to 14% in adult patients, whereas this complication has rarely been reported in children. CASE DESCRIPTION: We herein report the first case, to our knowledge, of an extremely rare subarachnoid hemorrhage presentation of a child with a ruptured anterior cerebral artery dissecting aneurysm secondary to a newly discovered, unilateral Moyamoya-like pathology. CONCLUSIONS: MMD-associated aneurysms are extremely rare in children, and hemorrhage may be the initial presentation of the disease. Prompt intervention is essential to exclude the ruptured aneurysm that is at risk of rebleeding because of persistent hemodynamic stress.

Multimodality Image-Guided Sclerotherapy of Low-Flow Orbital Vascular Malformations: Report of Single-Center Experience.

PURPOSE: To evaluate the role of multimodality imaging tools for intraprocedural guidance and outcome evaluation during sclerotherapy of low-flow orbital vascular malformations. MATERIALS AND METHODS: A retrospective review was performed of 17 consecutive patients with low-flow orbital malformations (14 lymphatic, two venous, and one venolymphatic) who underwent multimodality image-guided sclerotherapy between November 2012 and May 2015. Sclerotherapy technique, image guidance tools, and complications were recorded. Sclerotherapy outcome was evaluated using clinical response, magnetic resonance (MR) image-based lesion volumetry, and proptosis quantification. RESULTS: There were 22 sclerotherapy sessions performed. Intraprocedural ultrasound (US), fluoroscopy, cone-beam computed tomography (CT) and MR image fusion were used for image guidance with 100% technical success. Resolution of presenting symptoms was observed in all patients at 1-month follow-up. Four major sclerotherapy complications were successfully managed. Statistically significant reduction in lesion volume (P = .001) and proptosis (P = .0117) by MR image analysis was achieved in all patients in whom 3-month follow-up MR imaging was available (n = 13/17). There was no lesion recurrence at a median follow-up of 18 months (range, 8-38 mo). CONCLUSIONS: Multimodality imaging tools, including US, fluoroscopy, cone-beam CT, and MR fusion, during sclerotherapy of low-flow orbital malformations provide intraprocedural guidance and quantitative image-based evaluation of treatment outcome.

Evaluation of C-arm CT metal artifact reduction algorithm during intra-aneurysmal coil embolization: Assessment of brain parenchyma, stents and flow-diverters.

PURPOSE: Flat panel C-arm CT images acquired in the interventional suite provide valuable information regarding brain parenchyma, vasculature, and device status during the procedure. However, these images often suffer from severe streak artifacts due to the presence of metallic objects such as coils. These artifacts limit the capability to make diagnostic inferences and thus need to be reduced for better image interpretation. The main purpose of this paper is to systematically evaluate the accuracy of one such C-arm CT based metal artifact reduction (MAR) algorithm and to demonstrate its usage in both stent and flow diverter assisted coil embolization procedures. METHODS: C-arm CT images routinely acquired in 24 patients during coil embolization procedure (stent-assisted (12) and flow-diverter assisted (12)) were included in this study in a retrospective fashion. These images were reconstructed without and with MAR algorithm on an offline workstation and compared using quantitative image analysis metrics. This analysis was carried out to assess the improvements in both brain parenchyma and device visibility with MAR algorithm. Further, ground truth reference images from phantom experiments and clinical data were used for accurate assessment. RESULTS: Quantitative image analysis of brain parenchyma showed uniform distribution of grayscale values and reduced image noise after MAR correction. The line profile plot analysis of device profile in both phantom and clinical data demonstrated improved device visibility with MAR correction. CONCLUSIONS: MAR algorithm successfully reduced streak artifacts from coil embolization in all cases, thus allowing more accurate assessment of devices and adjacent brain parenchyma.

Metal coverage ratio of pipeline embolization device for treatment of unruptured aneurysms: Reality check.

BACKGROUND AND PURPOSE: The metal coverage ratio (MCR) of a flow diverter influences the intra-aneurysmal hemodynamics; a high MCR will occlude an aneurysm early, while a low MCR may delay aneurysm occlusion. The true MCR of a pipeline embolization device (PED) could be lower due to oversize, device deformation, or aneurysm location. In this study deviation of the true MCR from the nominal MCR is assessed and whether their difference affects aneurysm occlusion rate is determined. METHODS: A total of 40 consecutive patients, each of them treated by one PED for their aneurysms at the internal carotid artery (ICA), were retrospectively analyzed. The DynaCT images of these deployed PEDs were used to determine their true dimensions and estimate three MCRs (local, mean, and nominal). These data were compared in two groups of patients who had different aneurysm outcomes at six months. RESULTS: The difference in the local MCR between two groups is small, but statistically significant (24.5% vs 21.6%, p=05). The local MCR is consistently lower than the nominal MCRs (23.2% vs 30.2%, p<0.001); however, the difference between the mean and local MCRs is small (23.9% vs 23.2%). CONCLUSIONS: An expectation that a PED can achieve a MCR of 30% may not be reasonable. Device oversize and deformation during deployment lower the local MCR by 5-7%. A lowered MCR affects the aneurysm occlusion rate at six months.

Incidence and clinical implications of carotid branch occlusion following treatment of internal carotid artery aneurysms with the pipeline embolization device.

BACKGROUND: The use of flow diverters such as the pipeline embolization device (PED) for treatment of intracranial aneurysms carries the risk of side branch occlusion. OBJECTIVE: To determine the incidence and clinical outcomes associated with supraclinoid internal carotid artery (ICA) branch occlusion after deployment of PEDs for ICA aneurysms. METHODS: We reviewed patients who underwent endovascular treatment with PEDs for ICA aneurysms between June 2011 and March 2013. Forty-nine patients (43 women, mean age 56.3±1.8 years, 68 aneurysms) in whom PEDs traversed the origin of supraclinoid ICA branches (ophthalmic [OA], posterior communicating [PcommA], and anterior choroidal artery [AChA]) were selected for this study. Follow-up angiograms (mean follow-up, 12.8±0.8 months) were studied to determine the location of PEDs and the patency of ICA branches. RESULTS: PEDs were placed across the ostia of 49 OAs, 14 PcommAs, and 11 AChAs. Multiple PEDs were deployed in 16 patients. Rate of branch occlusion was 4% (2/49) for the OA, 7.1% (1/14) for the PcommA, and 0% for the AChA. Patients with branch occlusion did not endure new neurological deficits. ICA branch occlusion was not associated with the number of PEDs covering the ostia (P=.76) or the origin of ICA branches from the aneurysm (P=.24). CONCLUSION: The incidence of major supraclinoid ICA branch occlusion after treatment with PEDs was low. These events were not associated with new neurological deficits nor were they related to the number of PEDs deployed or the origin of ICA branches from the aneurysm.

Emergency endovascular management of penetrating gunshot injuries to the arteries in the face and neck: a case series and review of the literature.

INTRODUCTION: Penetrating gunshot injuries (GSI) to supra-aortic arteries that cause life-threatening blood loss or major neurologic deficits are increasingly managed using modern endovascular treatment (EVT). We report our experience with EVT of acute GSIs and review the existing literature. METHODS: Emergency EVT was performed in nine of 10 patients (7 men, age 17-50 years) with acute GSIs to supra-aortic arteries requiring acute management. One patient presented with acute and delayed injuries and underwent EVT 4 weeks after initial admission. Patient selection was based on clinical presentation and radiographic findings from a cohort of 55 patients with GSIs to the face, neck or head between February 2009 and March 2012. RESULTS: EVT was successfully performed in all patients. Two transections of the vertebral arteries were embolized with coils and/or liquid embolic agent (acrylic glue). Eight penetrated external carotid artery branches were occluded with liquid embolic agents (acrylic glue or Onyx) or particles. One severe dissection of the internal carotid artery with a subsequent thromboembolic event was treated with stenting. All except one patient survived with minor or no residual deficits. CONCLUSIONS: Emergency management of GSI injuries to the head and neck may involve all aspects of current EVT. Understanding endovascular techniques and being able to make rapid and appropriate treatment decisions in the setting of acute GSI to the face and neck can be a life-saving measure and greatly benefits the patient's outcome.

Retrieval of distorted pipeline embolic device using snare-loop.

BACKGROUND: Flow-diverter stents are increasingly being used in the endovascular treatment of intracranial aneurysms. Because of this increased usage, the occurrence of stent malpositioning, intra-arterial distortion, or migration will likely increase as well. METHODS: We describe the conformational twisting and deformity of a pipeline embolic device (PED) stent (Covidien, EV3) within the carotid artery during stent placement, with the subsequent immediate removal of the stent by using an endovascular snare-loop to successfully remove the device. RESULTS: The PED can be successfully removed using a snare-loop device when indicated. In this case, following removal of the initial PED, the aneurysms can be successfully treated with the placement of a second PED. CONCLUSION: It is critical to have a contingency plan for the removal of malpositioned or otherwise deformed stents that could potentially represent significant sources of iatrogenic stroke.

Extensive bilateral vertebral artery remodeling following treatment of dissection using pipeline embolic device.

BACKGROUND: Cerebral artery dissection remains a significant cause of stroke, and the mainstay of treatment has been medical management with anticoagulation, although flow-diverting stents have been used in some cases of arterial dissection resistant to medical management. METHODS: We present a case report of bilateral vertebral artery stenting using pipeline embolic device flow-diverting stents, after failed medical management of the dissection. RESULTS: This case demonstrated substantial subsequent vertebral arterial remodeling and good clinical outcome with maintenance of posterior circulation. The patient did not suffer any further strokes or posterior circulation symptoms following vertebral artery remodeling. CONCLUSION: In cases where traditional management of arterial dissection has not been efficacious, flow-diverting stents may be useful in treating dissections of the posterior cerebral circulation, even with bilateral involvement.

Management of ruptured dissecting intracranial aneurysms in infants: report of four cases and review of the literature.

BACKGROUND: Intracranial cerebral aneurysms in the pediatric population are infrequent, and those occurring in infants less than 1 year old are extremely rare. Of intracranial aneurysms in children, dissecting aneurysms are the most common type seen. While spontaneous dissecting aneurysms usually present with ischemia, hemorrhage can also occur. METHODS: A retrospective review of our patients revealed that from July 1, 2007 to June 30, 2012, four infants were treated for ruptured distal dissecting intracranial aneurysms at Texas Children's Hospital. Mycotic aneurysms and collagen vascular disorder were excluded in all four cases. All patients presented in our series presented with subarachnoid hemorrhage, and three had intraventricular hemorrhage. All patients underwent conventional catheter angiography for diagnosis. All patients in this series were managed in the acute or subacute period with surgical or endovascular trapping without distal bypass procedures. All four patients tolerated sacrifice of the parent vessels feeding these distal aneurysms well. CASE REPORT AND REVIEW OF LITERATURE: We describe the presentation and management of these rare cases and then review the current literature on the management of these dissecting aneurysms in infants.

Hemodynamics of small aneurysm pairs at the internal carotid artery.

Cerebral aneurysms carry significant risks because rupture-related subarachnoid hemorrhage leads to serious and often fatal consequences. The rupture risk increases considerably for multiple aneurysms. Multiple aneurysms can grow from the same location of an artery, and the interaction between these aneurysms raises the rupture risk even higher. Four aneurysm pair cases at the internal carotid artery are investigated for their hemodynamic behaviors using patient-specific modeling. For each case, aneurysms are separated from the parent artery and three models are reconstructed, one with two aneurysms and the other two models with only one of the two aneurysms. Results show that the relative anatomic location of one aneurysm to the other may determine the hemodynamic environment of an aneurysm. The presence of a proximal aneurysm reduces the intra-aneurysmal flow into the distal aneurysm; the proximal aneurysm and larger aneurysm have a greater area under low wall shear stress. The average intra-aneurysmal inflow ratio ranges from 16% to 41%, and reduction of the inflow ratio by an aneurysm pair varies from 6% to 15%. The maximum wall shear stress increases for serial aneurysms, but decreases for parallel aneurysms. Interaction between parallel aneurysms is not significant; however, the proximal aneurysm in serial aneurysms may be subject to a greater rupture risk.

An imageable retinoid acid derivative to detect human cancer xenografts and study therapeutic dosing to reduce its toxicity.

Developing agents with 'seek, treat and see' capability is critical for personalized molecular medicine. Those agents will specifically target the disease markers for diagnosis and apply the biologically effective dose for treatment. Retinoids regulate a multitude of biological processes. In addition, retinoic acid can reverse premalignancy, significantly decrease second primary tumors and provide a treatment benefit in head and neck, lung, esophagus, colon and bladder cancer. These data suggest that cancer cells can take up retinoids. Therefore, retinoids are potential tumor-imaging agents. We developed near-infrared (NIR)-labeled retinoid agents to detect human cancers, visualize drug redistribution within the body, determine the optimal biological dose and reduce systemic toxicity. Our data demonstrate that the retinoid agent, but not the free dye, binds to the human tumor cells and is internalized, where it permits the imaging of human cancer xenografts. The high dose of retinoid agent is significantly associated with systemic toxicity. In summary, synthetic NIR-labeled retinoid agents can be used to detect multiple human cancer xenografts as the agent is internalized by cancer cells. The binding of the agent to the tumor xenografts is dependent on the redistribution of the agent. Therapeutic agents labeled with reporters will interrogate tumor-drug interactions and permit analysis of biodistribution, pharmacokinetics and pharmacodynamics in real time. At the same time, we can apply the biologically effective dose for therapy, instead of the traditional maximum tolerated dose, to reduce systemic toxicity.

Target-specific agents imaging ectopic and orthotopic human pancreatic cancer xenografts.

OBJECTIVES: This study aimed to develop target-specific binding agents for in vitro and in vivo imaging of human pancreatic cancer. METHODS: A monoclonal neutrophil gelatinase-associated lipocalin (NGAL)-specific antibody and a peptide specific for matrix metalloproteinase (MMP) were labeled with a near-infrared dye for in vitro and in vivo imaging studies. Fluorescence or confocal microscopy was used to determine antibody or peptide binding and internalization of agents into human AsPC-1, Panc-1, and MiaPaCa pancreatic cancer cell lines and in mice bearing ectopic or orthotopic pancreatic tumor transplants. RESULTS: Both the NGAL-specific antibody and MMP peptide bound to pancreatic cancer cells with high specificity; most NGAL-specific antibody localized to the cytosol. In vivo imaging results demonstrated high signal intensity of both agents bound to the tumor. The average tumortr-to-background ratio of antibody and peptide was 1.29 and 2.86, respectively. Signal was also detectable in the liver, kidneys, and bladder. CONCLUSIONS: Both NGAL-specific antibody and MMP peptide bound to cancer cells, and the labeled antibody was internalized. These results demonstrate that both agents can be used to enhance detection of human pancreatic cancer xenografts. However, the biodistribution patterns of these agents might limit their use in research and clinical practice.

Surgical cannulation of a cortical draining vein for endovascular treatment of a dural arteriovenous fistula of the cavernous sinus.

Dural arteriovenous fistulas (DAVF) of the cavernous sinus most commonly present with ocular symptoms and can be observed or treated with endovascular approaches, surgery, or radiosurgery. Combined surgical-endovascular approaches have been used for fistulas that are not amenable to standard endovascular approaches. A 40-year-old man presented with ocular symptoms from a cavernous sinus DAVF. Multiple previous transarterial and transvenous embolization attempts had failed. The patient underwent craniotomy for surgical exposure and cannulation of an arterialized sylvian vein. Subsequently he underwent coiling and onyx embolization of the DAVF. The intervention resulted in effective obliteration of the fistula. If a cavernous sinus DAVF is refractory to treatment, surgical exposure and cannulation of a cortical draining vein can facilitate transvenous endovascular treatments.

Timing and size of flow impingement in a giant intracranial aneurysm at the internal carotid artery.

Flow impingement is regarded as a key factor for aneurysm formation and rupture. Wall shear stress (WSS) is often used to evaluate flow impingement even though WSS and impinging force are in two different directions; therefore, this raises an important question of whether using WSS for evaluation of flow impingement size is appropriate. Flow impinging behavior in a patient-specific model of a giant aneurysm (GA) at the internal carotid artery (ICA) was analyzed by computational fluid dynamics simulations. An Impingement Index (IMI) was used to evaluate the timing and size of flow impingement. In theory, the IMI is related to the WSS gradient, which is known to affect vascular biology of endothelial cells. Effect of non-Newtonian fluid, aneurysm size, and heart rate were also studied. Maximum WSS is found to be proportional to the IMI, but the area of high wall shear is not proportional to the size of impingement. A faster heart rate or larger aneurysm does not produce a larger impinging site, and the Newtonian assumption overestimates the size of impingement. Flow impingement at the dome occurs approximately 0.11 s after the peak of flow waveform is attained. This time delay also increases with aneurysm size and varies with heart rate and waveform.

Hemodynamic effect of Neuroform stent on intimal hyperplasia and thrombus formation in a carotid aneurysm.

Stents play an important role in management of cerebral aneurysms. A stent reconstructs the parent artery, assists coil embolization, and decreases flow activity within an aneurysm. However, an in-stent stenosis often occurs within the stented artery and compromises the circulation at the parent artery. Hemodynamic basis of re-stenoses from aneurysm stenting is not fully understood. An 8mm cavernous carotid aneurysm with a wide neck was treated by a Neuroform stent first and by coils five weeks later. A comparison of the difference in morphology during this five-week period reveals the presence of intimal hyperplasia in the internal carotid artery, 1.3mm thick at the proximal end and 1mm at the distal end of the stent, and 1mm thick thrombus at the postero-inferior side of the aneurysm. Computational fluid dynamic analyses show that the site of intimal hyperplasia is exposed to low wall shear with high oscillatory shear index (OSI), and the location of thrombus is subject to high OSI. Intimal hyperplasia and thrombus occur at comparable rates, but at different hemodynamic conditions; however, both prefer regions with high OSIs.

Cross-flow at the anterior communicating artery and its implication in cerebral aneurysm formation.

The anterior communicating artery (ACoA) is an important element of the circle of Willis. While the artery itself is short and small, a large number of intracranial aneurysms can be found at the ACoA. Four subject-specific ACoA models are constructed from 3D rotational angiographic images. The ACoA of these models ranged from 1.7 to 2.7 mm in diameter and 1.5 to 5.7 mm in length. Pulsatile flows through these four ACoA models are studied numerically. Blood is found to move in two opposite directions simultaneously within the ACoA, giving a much higher wall shear at the ACoA. These two opposite flow streams produce a cross-flow that is dependent on the flow rates at the anterior cerebral arteries and internal carotid arteries (ICAs). A larger and shorter ACoA allows flow through the ACoA easily, leading to a greater cross-flow and higher hemodynamic forces on the artery. This cross-flow may disappear when there is a sufficient net flow for a smaller and longer ACoA. Wall shear stress can be as high as 185 Pa at smaller ACoAs, but it can be lowered by asymmetric waveforms at the ICAs. A functional circle of Willis also promotes cross-flow at both the ACoA and posterior communicating arteries.