Development of the Circle of Willis Score (COWS) to help guide decision making during acute tandem occlusion treatment: Preliminary analysis.

BACKGROUND: Acute tandem occlusions (TOs) are challenging to treat. Although acute carotid stenting of the proximal lesion is well tolerated, there are certain situations when the practitioner may be wary of acute stenting (bleeding concerns). OBJECTIVE: The purpose of this study was to retrospectively study patients with tandem occlusions who had re-occlusion of the extracranial ICA and develop a Circle of Willis Score (COWS) to help predict which patients could forego acute stenting. METHODS: This is a retrospective review of TO patients with a persistent proximal occlusion following intervention (either expected or unexpected). Pre intervention CTA and intraoperative DSA were reviewed, and each patient was assigned a score 2 (complete COW), 1a (patent A1-Acomm-A1), 1p (patent Pcomm), or 0 (incomplete COW). Findings from the DSA took precedence over the CTA. Two cohorts were created, the complete COW cohort (COWS 2) versus the incomplete COW cohort (COWS 1a,1p, or 0). Angiographic outcomes were assessed using the mTICI score (2b-3) and clinical outcomes were assessed using discharge mRS (good outcome mRS 0-3). RESULTS: Of 68 TO cases, 12 had persistent proximal occlusions. There were 5/12 (42 %) patients in the complete COW cohort, and 7/12 (58 %) in the incomplete COW cohort (5/12 with scores of 1a/1p and 2/12 with a score of 0). In the complete COW cohort, there were 2 ICA-ICA and 3 ICA-MCA occlusions. In the incomplete COW cohort, there was one ICA-ICA occlusion and 6 ICA-MCA occlusions. LKW-puncture was shorter in the complete COW cohort (208 min vs. 464 min, p = 0.16). Successful reperfusion was higher in the complete COW cohort (100 % vs. 71 %). There was a trend toward better clinical outcomes in the complete COW cohort (80 % vs 29 %, p = 0.079). CONCLUSION: The COWS is a simple score that may help predict a successful clinical outcome without proximal revascularization when concerned about performing an acute carotid stent during TO treatment. Evaluation in larger TO cohort is warranted.

Re-examining decompressive craniectomy medial margin distance from midline as a metric for calculating the risk of post-traumatic hydrocephalus.

Decompressive craniectomy (DC) is a life-saving procedure in severe traumatic brain injury, but is associated with higher rates of post-traumatic hydrocephalus (PTH). The relationship between the medial craniectomy margin's proximity to midline and frequency of developing PTH is controversial. The primary study objective was to determine whether average medial craniectomy margin distance from midline was closer to midline in patients who developed PTH after DC for severe TBI compared to patients that did not. The secondary objective was to determine if a threshold distance from midline could be identified, at which the risk of developing PTH increased if the DC was performed closer to midline than this threshold. A retrospective review was performed of 380 patients undergoing DC at a single institution between March 2004 and November 2014. Clinical, operative and demographic variables were collected, including age, sex, DC parameters and occurrence of PTH. Statistical analysis compared mean axial craniectomy margin distance from midline in patients with versus without PTH. Distances from midline were tested as potential thresholds. No significant difference was identified in mean axial craniectomy margin distance from midline in patients developing PTH compared with patients with no PTH (n = 24, 12.8 mm versus n = 356, 16.6 mm respectively, p = 0.086). No significant cutoff distance from midline was identified (n = 212, p = 0.201). This study, the largest to date, was unable to identify a threshold with sufficient discrimination to support clinical recommendations in terms of DC margins with regard to midline, including thresholds reportedly significant in previously published research.

Osteosarcoma of the skull base presenting as a petrocavernous pseudoaneurysm and masquerading as an intracranial abscess: illustrative case.

BACKGROUND: Telangiectatic osteosarcoma (TOS) is a rare and aggressive high-grade malignant neoplasm composed of blood-filled or empty cystic spaces resembling aneurysmal bone cysts. Uncommonly, TOSs can occur in the skull base. OBSERVATIONS: The authors present a case of a TOS that presented as a petrocavernous carotid pseudoaneurysm and then masqueraded as an intracranial abscess. The prognosis for TOSs with intracranial involvement is typically unfavorable and inversely related to the degree of intracranial involvement. LESSONS: Skull-based malignancies should be part of the differential diagnosis for a rapidly progressing lesion. Recovery of polymicrobial organisms during endoscopic sinus surgery should prompt reconsideration of the differential diagnosis. Postinflammatory changes from endovascular coiling have been described and can confound imaging and clinical findings.

Republished: Successful treatment of direct carotid-cavernous fistula in a patient with Ehlers-Danlos syndrome type IV without arterial puncture: the transvenous triple-overlay embolization (TAILOREd) technique.

We report successful transvenous treatment of direct carotid-cavernous fistula in a patient with Ehlers-Danlos syndrome type IV using a novel triple-overlay embolization (TAILOREd) technique without the need for arterial puncture, which is known to be highly risky in this patient group. The TAILOREd technique allowed for successful treatment using preoperative MR angiography as a three-dimensional overlay roadmap combined with cone beam CT and live fluoroscopy, precluding the need for an arterial puncture.

The ability of magnetic resonance black blood vessel wall imaging to evaluate blunt cerebrovascular injury following acute trauma.

BACKGROUND AND PURPOSE: Blunt cerebrovascular injury (BCVI) is associated with a significant risk of ischemic stroke when left untreated. Cross-sectional imaging is vital to early BCVI diagnosis and treatment; however, conventional luminal vessel imaging is limited in its ability to evaluate for vessel wall pathology. The purpose of this study is to evaluate the ability of vessel wall magnetic resonance imaging (VWI) to detect and evaluate BCVI in acutely injured trauma patients relative to neck computed tomographic angiography (CTA). MATERIALS AND METHODS: Trauma patients with suspected BCVI on initial neck CTA were prospectively recruited for VWI evaluation. Two neuroradiologists blinded to patient clinical history and CTA findings evaluated each artery independently on VWI and noted the presence and grade of BCVI. These results were subsequently compared to neck CTA findings relative to expert clinical consensus review. Interrater reliability of VWI for detecting BCVI was evaluated using a weighted Cohen κ-statistic. RESULTS: Ten trauma patients (40 cervical arteries) were prospectively evaluated using both CTA and VWI. Out of 18 vascular lesions identified as suspicious for BCVI on CTA, six lesions were determined to represent true BCVI by expert consensus review. There was almost perfect agreement between VWI and expert consensus regarding the presence and grade of BCVI (κ=0.82). This agreement increased when considering only low grade BCVI. There was only fair agreement between CTA and expert clinical consensus (κ=0.36). This agreement decreased when considering only low grade BCVI. CONCLUSIONS: VWI can potentially accurately identify and evaluate BCVI in acutely injured trauma patients with excellent inter-rater reliability.

Vessel wall MRI characteristics of endovascularly treated aneurysms: association with angiographic vasospasm.

OBJECTIVE: The aim of this paper was to evaluate the association between intracranial vessel wall MRI enhancement characteristics and the development of angiographic vasospasm in endovascularly treated aneurysm patients. METHODS: Consecutive cases of both ruptured and unruptured intracranial aneurysms that were treated endovascularly, followed by intracranial vessel wall MRI in the immediate postoperative period, were included. Two raters blinded to clinical data and follow-up imaging independently evaluated for the presence, pattern, and intensity of wall enhancement. Development of angiographic vasospasm was independently evaluated. Delayed cerebral ischemia; cerebral infarct; procedural details; and presence and grade of subarachnoid, parenchymal, and intraventricular hemorrhage were evaluated. Statistical associations were determined on a per-vessel segment and per-patient basis. RESULTS: Twenty-nine patients with 30 treated aneurysms (8 unruptured and 22 ruptured) were included in this study. Interobserver agreement was substantial for the presence of enhancement (κ = 0.67) and nearly perfect for distribution (κ = 0.87) and intensity (κ = 0.84) of wall enhancement. Patients with ruptured aneurysms had a significantly greater number of enhancing segments than those with unruptured aneurysms (29.9% vs 7.2%; OR 5.5, 95% CI 2.2-13.7). For ruptured cases, wall enhancement was significantly associated with subsequent angiographic vasospasm while controlling for grade of hemorrhage (adjusted OR 3.9, 95% CI 1.7-9.4). Vessel segments affected by balloon, stent, or flow-diverter use demonstrated greater enhancement than those not affected (OR 22.7, 95% CI 5.3-97.2 for ruptured; and OR 12.9, 95% CI 3.3-49.8 for unruptured). CONCLUSIONS: Vessel wall enhancement after endovascular treatment of ruptured aneurysms is associated with subsequent angiographic vasospasm.

Timing of cranioplasty: a 10.75-year single-center analysis of 754 patients.

OBJECTIVE Despite their technical simplicity, cranioplasty procedures carry high reported morbidity rates. The authors here present the largest study to date on complications after cranioplasty, focusing specifically on the relationship between complications and timing of the operation. METHODS The authors retrospectively reviewed all cranioplasty cases performed at Harborview Medical Center over the past 10.75 years. In addition to relevant clinical and demographic characteristics, patient morbidity and mortality data were abstracted from the electronic medical record. Cox proportional-hazards models were used to analyze variables potentially associated with the risk of infection, hydrocephalus, seizure, hematoma, and bone flap resorption. RESULTS Over the course of 10.75 years, 754 cranioplasties were performed at a single institution. Sixty percent of the patients who underwent these cranioplasties were male, and the median follow-up overall was 233 days. The 30-day mortality rate was 0.26% (2 cases, both due to postoperative epidural hematoma). Overall, 24.6% percent of the patients experienced at least 1 complication including infection necessitating explantation of the flap (6.6%), postoperative hydrocephalus requiring a shunt (9.0%), resorption of the flap requiring synthetic cranioplasty (6.3%), seizure (4.1%), postoperative hematoma requiring evacuation (2.3%), and other (1.6%). The rate of infection was significantly higher if the cranioplasty had been performed < 14 days after the initial craniectomy (p = 0.007, Holm-Bonferroni-adjusted p = 0.028). Hydrocephalus was significantly correlated with time to cranioplasty (OR 0.92 per 10-day increase, p < 0.001) and was most common in patients whose cranioplasty had been performed < 90 days after initial craniectomy. New-onset seizure, however, only occurred in patients who had undergone their cranioplasty > 90 days after initial craniectomy. Bone flap resorption was the least likely complication for patients whose cranioplasty had been performed between 15 and 30 days after initial craniectomy. Resorption was also correlated with patient age, with a hazard ratio of 0.67 per increase of 10 years of age (p = 0.001). CONCLUSIONS Cranioplasty performed between 15 and 30 days after initial craniectomy may minimize infection, seizure, and bone flap resorption, whereas waiting > 90 days may minimize hydrocephalus but may increase the risk of seizure.

Dolichoectatic aneurysms of the vertebrobasilar system: clinical and radiographic factors that predict poor outcomes.

OBJECTIVE Fusiform dolichoectatic vertebrobasilar aneurysms are rare, challenging lesions. The natural history of these lesions and medium- and long-term patient outcomes are poorly understood. The authors sought to evaluate patient prognosis after diagnosis of fusiform dolichoectatic vertebrobasilar aneurysms and to identify clinical and radiographic predictors of neurological deterioration. METHODS The authors reviewed multiple, prospectively maintained, single-provider databases at 3 large-volume cerebrovascular centers to obtain data on patients with unruptured, fusiform, basilar artery dolichoectatic aneurysms diagnosed between January 1, 2000, and January 1, 2015. RESULTS A total of 50 patients (33 men, 17 women) were identified; mean clinical follow-up was 50.1 months and mean radiographic follow-up was 32.4 months. At last follow-up, 42% (n = 21) of aneurysms had progressed and 44% (n = 22) of patients had deterioration of their modified Rankin Scale scores. When patients were dichotomized into 2 groups- those who worsened and those who did not-univariate analysis showed 5 variables to be statistically significantly different: sex (p = 0.007), radiographic brainstem compression (p = 0.03), clinical posterior fossa compression (p < 0.001), aneurysmal growth on subsequent imaging (p = 0.001), and surgical therapy (p = 0.006). A binary logistic regression was then created to evaluate these variables. The only variable found to be a statistically significant predictor of clinical worsening was clinical symptoms of posterior fossa compression at presentation (p = 0.01). CONCLUSIONS Fusiform dolichoectatic vertebrobasilar aneurysms carry a poor prognosis, with approximately one-half of the patients deteriorating or experiencing progression of their aneurysm within 5 years. Despite being high risk, intervention-when carefully timed (before neurological decline)-may be beneficial in select patients.

Retrograde 3D rotational venography (3DRV) for venous sinus stent placement in idiopathic intracranial hypertension.

BACKGROUND: Dural venous sinus stenting has emerged as an effective and durable treatment for idiopathic intracranial hypertension (IIH). Improved visualization of the venous sinuses can improve stent placement. METHODS: We present two cases of IIH treated with venous sinus stenting in which retrograde three-dimensional rotational venography (3DRV) provided superior anatomical details of the venous sinuses for optimal sizing and positioning of stent. RESULTS: Comparison of pre-stent 3DRV with post-stent contrast-enhanced flat panel detector CT allowed confirmation of stent placement and the result of stenosis dilation. CONCLUSION: This 3DRV technique provides precise visualization of venous sinus stenosis prior to stenting without the need for arterial cerebral angiography during the treatment course.

Endovascular Coil Retrieval Using Dual Synchronous Solitaire Revascularization Devices.

BACKGROUND AND IMPORTANCE: Coil migration is a potential complication of endovascular aneurysm treatment. Dislodged coils into the parent artery require retrieval to prevent thromboembolic complications. A variety of techniques for coil retrieval have been described, including the use of single stentrievers and aspiration catheters. CLINICAL PRESENTATION: The use of 2 stentrievers, as opposed to a single device, was thought to be advantageous in coil removal by the additional point of friction due to the extensive length of coil stretching and earlier failure of a single device. CONCLUSION: In this report, 2 synchronous Solitaire FR Revascularization Devices (Covidien/Medtronic, Dublin, Ireland) were deployed, 1 distal and 1 proximal, to retrieve an inadvertently deployed coil.

Angiographic perfusion imaging of intracranial stenting.

Two-dimensional angiographic perfusion imaging (2DAP) is a new technique permitting perfusion imaging during angiography, and has been used to study cerebral vasospasm. Here we report our experience with this technique following angioplasty and stent placement in a patient with symptomatic and medically refractory stenosis of the right supraclinoid internal carotid artery. We found that intraprocedural angiographic perfusion imaging provided real-time and objective evidence of improved cerebral perfusion during intervention. Following treatment, the patient remains symptom-free at last follow-up.

Population Based Paternity Rate and Partner Birth Outcomes Among Utah Men With Inflammatory Bowel Disease.

OBJECTIVES: Crohn's disease (CD) and ulcerative colitis (UC) impact an estimated 350,000 reproductive age men in the United States. The reproductive consequences are largely unknown. The objective of this study was to evaluate the effects of CD and UC on reproductive outcomes. METHODS: From the Utah Population Database, we identified a cohort of male patients with CD (1,245) and UC (1,368). Male-sibling controls were identified, and birth outcome data from offspring were obtained. Analyses for CD and UC were completed separately. RESULTS: Among UC patients (473) with at least one male sibling (1,020), 66% had offspring, which was not different compared with siblings (61%, P=0.16). Birth outcomes were not different between UC patients and male siblings: congenital malformations (UC 6% vs. 6%, P=0.99), perinatal complications (UC 35% vs. 31%, P=0.23), mean birth weight (UC 3,347 vs. 3,357 g, P=0.53), mean length of gestation (UC 39.0 vs. 39.1 weeks, P=0.54). Among CD patients (421) with at least one male sibling (833), 58% had offspring, which did not differ compared with siblings (57%, P=0.77). Similarly, there were no differences in partner birth outcomes: congenital malformations (CD 7% vs. 6%, P=0.27), perinatal complications (CD 35% vs. 32%, P=0.12), mean birth weight (CD 3,276 vs. 3,324 g, P=0.13), or mean length of gestation (38.8 vs. 39 weeks, P=0.24). CONCLUSIONS: We found no differences in paternity rate or female partner birth outcomes in Utah men with UC or CD compared with male-sibling controls. UC and CD do not appear to affect the reproductive outcomes of men in Utah.

Risk of Complications with Simultaneous Cranioplasty and Placement of Ventriculoperitoneal Shunt.

BACKGROUND: The development of hydrocephalus (HCP) necessitating placement of a ventriculoperitoneal shunt (VPS) after decompressive hemicraniectomy occurs at a rate of approximately 5%-15%. The ideal approach for addressing both HCP and a cranial defect remains unclear, and whether concomitant VPS and cranioplasty (CP) increases the risk of complications is uncertain. METHODS: This is a retrospective cohort study of adult patients who underwent CP and VPS placement for any indication at Harborview Medical Center, Seattle between March 2004 and November 2014 with at least 30 days of follow-up. The primary variable of interest was the timing of CP relative to VPS placement. The outcomes of interest were CP- and VPS-related infections, early (within 1 year of placement) VPS obstruction, and a composite of any of these complications in a single patient. RESULTS: The rate of composite outcomes was 15% in the subgroup of patients with simultaneous CP and VPS placement, compared with 29% in the subgroup of patients in whom CP and VPS placement were performed separately, a non-statistically significant difference (P = 0.24). Similarly, there was no statistically significant difference between the subgroups in any of the 3 individual outcomes of interest, which remained after accounting for potential covariates in a multivariate regression model. CONCLUSIONS: In our study population, there was no difference between simultaneous and separate CP and VPS placement with respect to CP infection, VPS infection, and VPS mechanical failure/obstruction. There is equipoise in the current literature regarding the safety of performing these 2 common procedures simultaneously, with studies of similar size and design finding variable degrees of safety of this practice.

Successful treatment of direct carotid-cavernous fistula in a patient with Ehlers-Danlos syndrome type IV without arterial puncture: the transvenous triple-overlay embolization (TAILOREd) technique.

We report successful transvenous treatment of direct carotid-cavernous fistula in a patient with Ehlers-Danlos syndrome type IV using a novel triple-overlay embolization (TAILOREd) technique without the need for arterial puncture, which is known to be highly risky in this patient group. The TAILOREd technique allowed for successful treatment using preoperative MR angiography as a three-dimensional overlay roadmap combined with cone beam CT and live fluoroscopy, precluding the need for an arterial puncture.

Population-based Semen Analysis Results and Fertility Among Patients With Inflammatory Bowel Disease: Results From Subfertility Health Assisted Reproduction and the Environment (SHARE) Study.

OBJECTIVE: To evaluate male fertility in Crohn disease (CD) and ulcerative colitis (UC) by examining semen analysis results and paternity from the SHARE study (Subfertility Health Assisted Reproduction and the Environment), a population-based cohort of semen analysis results from Utah men. METHODS: A population-based cohort of men with CD or UC was identified using the Utah Population Database (contains person-level linked demographic, genealogical, and medical record information for 85% of Utahans) from 1996 to 2014, and validated by clinical chart review. This cohort was then cross-linked (n = 55) to the SHARE population dataset of semen analysis results. Men with CD or UC were compared with population-based, age-matched, paired (1:1) controls (n = 47). Paternity was evaluated though presence and number of linked offspring and inter-birth interval. RESULTS: Offspring were identified in 71% of UC patients (mean of 1.8 children) and 61% of CD patients (mean of 1.2 children). Compared with matched controls, there were no differences in number of offspring, mean inter-birth interval, or any of the evaluated semen analysis parameters among either men with CD or UC. CONCLUSION: Fertility and semen analysis values among men with UC or CD are not significantly impacted compared with population-based, age-matched controls.

Combined direct and indirect traumatic carotid-cavernous fistula (CCF): Case report and review of the literature.

BACKGROUND: Within the current Barrow classification system, there are no categorical descriptions or reports in the literature of cavernous carotid fistulas (CCFs) with both a direct component (type A) and separate indirect contribution (type B, C, or D). We report the first definitive case of a combined simultaneous traumatic direct and indirect CCF, and review the literature on the similar existing entity of traumatic indirect CCFs presenting delayed and subsequent to the treatment of traumatic, direct CCFs. METHODS: We report a case of simultaneous direct type A CCF with a traumatic indirect CCF component and a review of the relevant literature. RESULTS: An 18year-old female presented after a motor vehicle collision. A diagnostic cerebral angiogram confirmed the diagnosis of CCF, with contribution both directly from the ICA and indirectly via branches of the ECA. The direct component of the CCF was first treated in 3 stages via both transarterial and transvenous coil embolization, followed by a final 4th stage of parent vessel sacrifice in order to treat the residual direct component, with transarterial embolization to treat residual indirect CCF activity. CONCLUSIONS: To our knowledge, this is the first report of a traumatic CCF with simultaneous direct (type A) and indirect via the ECA (type C) contributions.

Respiratory and Swallowing Outcomes Based on Aneurysm Location in 360 Patients with Subarachnoid Hemorrhage.

INTRODUCTION: Aneurysmal subarachnoid hemorrhage (aSAH) may result in abnormal respiratory and swallowing function. We analyzed factors that may influence long-term respiratory and swallowing function in aSAH patients and compared patients with anterior and posterior aneurysm locations. METHODS: We retrospectively reviewed 360 consecutive aSAH patients. We recorded location of the aneurysm and respiratory indices on admission, in-hospital adverse respiratory events, and the need for tracheostomy (for respiratory failure) or percutaneous endoscopic gastrostomy (PEG) tube (for prolonged dysphagia). Respiratory and swallowing function was also reviewed at 1 year and at most recent clinical follow-up. RESULTS: Aneurysms consisted of 293 described as anterior circulation (81.4%) and 67 described as posterior circulation (18.6%), including 31 patients with basilar artery aneurysms and 16 with posterior inferior cerebellar artery (PICA) aneurysms. There were no differences in oxygen saturation or PaO2:FiO2 ratio on admission, though patients with PICA aneurysms presented significantly more commonly with endotracheal intubation. PICA aneurysm patients had higher rates of tracheostomy and PEG tube dependence at 1 year in univariate analysis. Higher Hunt-Hess grade was a predictor of pneumonia and prolonged intubation, whereas older age and prolonged hospitalization were predictors of PEG placement in multivariate analysis. CONCLUSIONS: Ruptured anterior and posterior circulation aneurysms have similar rates of in-hospital respiratory and swallowing dysfunction. There was a higher rate of swallowing dysfunction in the posterior circulation aneurysm group compared with the anterior group at most recent follow-up (12% vs. 2%, P = 0.035). Patients with PICA aneurysms demonstrated higher rates of tracheostomy and PEG, though the latter did not achieve statistical significance.

The use of ultrasound for postoperative monitoring of cerebral bypass grafts: A technical report.

Duplex ultrasound and transcranial Doppler are valuable tools for post-operative monitoring of extracranial-intracranial cerebral bypass grafts. Here we describe our technique for the evaluation of both high-flow and low-flow cerebral bypass grafts over a nine year period. 186 bypass grafts were studied daily during the inpatient period between Jan 2005 and Dec 2014 after surgery for various cerebrovascular pathologies. There was a technical success rate of 97%. Duplex ultrasonographic flow measurements had excellent interobserver reliability with an intraclass correlation coefficient (ICC) of 0.89 (p=0.009). Technical nuances are highlighted and a brief discussion of pathology is undertaken.

Computational fluid dynamics of cerebral aneurysm coiling using high-resolution and high-energy synchrotron X-ray microtomography: comparison with the homogeneous porous medium approach.

BACKGROUND: Computational modeling of intracranial aneurysms provides insights into the influence of hemodynamics on aneurysm growth, rupture, and treatment outcome. Standard modeling of coiled aneurysms simplifies the complex geometry of the coil mass into a homogeneous porous medium that fills the aneurysmal sac. We compare hemodynamics of coiled aneurysms modeled from high-resolution imaging with those from the same aneurysms modeled following the standard technique, in an effort to characterize sources of error from the simplified model. MATERIALS: Physical models of two unruptured aneurysms were created using three-dimensional printing. The models were treated with coil embolization using the same coils as those used in actual patient treatment and then scanned by synchrotron X-ray microtomography to obtain high-resolution imaging of the coil mass. Computational modeling of each aneurysm was performed using patient-specific boundary conditions. The coils were modeled using the simplified porous medium or by incorporating the X-ray imaged coil surface, and the differences in hemodynamic variables were assessed. RESULTS: X-ray microtomographic imaging of coils and incorporation into computational models were successful for both aneurysms. Porous medium calculations of coiled aneurysm hemodynamics overestimated intra-aneurysmal flow, underestimated oscillatory shear index and viscous dissipation, and over- or underpredicted wall shear stress (WSS) and WSS gradient compared with X-ray-based coiled computational fluid dynamics models. CONCLUSIONS: Computational modeling of coiled intracranial aneurysms using the porous medium approach may inaccurately estimate key hemodynamic variables compared with models incorporating high-resolution synchrotron X-ray microtomographic imaging of complex aneurysm coil geometry.