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This is a comparative study of two novel noninvasive cerebrovascular autoregulation (CA) monitoring methods based on intracranial blood volume (IBV) changes in the human brain. We investigated the clinical applicability of the new volumetric reactivity index (VRx2), reflected by intracranial ultrasonic attenuation dynamics for noninvasive CA monitoring. The CA was determined noninvasively on 43 healthy participants by calculating the volumetric reactivity index (VRx1 from time-of-flight of ultrasound, VRx2 from attenuation of ultrasound). The VRx was calculated as a moving correlation coefficient between the arterial blood pressure and noninvasively measured IBV slow waves. Linear regression between VRx1 and VRx2 (averaged per participants) showed a significant correlation (r = 0.731, p < 0.0001, 95% confidence interval [0.501-0.895]) in data filtered by bandpass filtering. On the other hand, FIR filtering demonstrated a slightly better correlation (r = 0.769, p < 0.0001, 95% confidence interval [0.611-0.909]). The standard deviation of the difference by bandpass filtering was 0.1647 and bias -0.3444; and by FIR filtering 0.1382 and bias -0.3669. This comparative study showed a significant coincidence of the VRx2 index compared to that of VRx1. Hence, VRx2 could be used as an alternative, cost-effective noninvasive cerebrovascular autoregulation index in the same way as VRx1 values are used.

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Intracranial aneurysms confer the risk of subarachnoid hemorrhage (SAH), a potentially devastating condition, though most aneurysms will remain asymptomatic for the lifetime of the patient. Imaging is critical to all stages of patient care for those who harbor an unruptured intracranial aneurysm (UIA), including to establish the diagnosis, to determine therapeutic options, to undertake surveillance in patients who elect not to undergo treatment or whose aneurysm(s) portends such a low risk that treatment is not indicated, and to perform follow-up after treatment. Neuroimaging is equally as important in patients who suffer an SAH. DSA remains the reference standard for imaging of intracranial aneurysms due to its high spatial and temporal resolution. As noninvasive imaging technology, such as CTA and MRA, improves, the diagnostic accuracy of such tests continues to increasingly approximate that of DSA. In cases of angiographically negative SAH, imaging protocols are necessary not only for diagnosis but also to search for an initially occult vascular lesion, such as a thrombosed, ruptured aneurysm that might be detected in a delayed fashion. Given the crucial role of neuroimaging in all aspects of care for patients with UIAs and SAH, it is incumbent on those who care for these patients, including cerebrovascular neurosurgeons, interventional neurologists and neuroradiologists, and diagnostic radiologists and neurointensivists, to understand the role of imaging in this disease and how individual members of the multispecialty team use imaging to ensure best practices to deliver cutting-edge care to these often complex cases. This review expounds on the role of imaging in the management of UIAs and ruptured intracranial aneurysms and in the workup of angiographically negative subarachnoid hemorrhage.

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Digital subtraction angiography (DSA) has long been the imaging gold standard in the evaluation, treatment, and follow-up of cerebro- and spinovascular disorders. However, DSA has the disadvantages of invasiveness, contrast allergy or nephropathy, the impracticality of procedural preparation and recovery, and expense. Contrast-enhanced (CE), time-resolved (TR) magnetic resonance angiography (CE TR-MRA) is a sophisticated, relatively novel imaging modality that provides multiphasic contrast-enhanced visualization of the neurovasculature. Given the crucial role of angiography in all aspects of care for patients with complex neurovascular disorders, it is incumbent on those who care for these patients to understand the usefulness and pitfalls of novel imaging in this arena to ensure best practices, and to deliver cutting edge care to these patients in a way that minimizes cost, but does not compromise quality. CE TR-MRA has the potential to play an expanded role in the workup and follow-up across the spectrum of neurovascular disease, and this review is aimed to help neurosurgeons better understand how CE TR-MRA can be used to better manage patients in this cohort.

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OBJECTIVE: The authors conducted a study to ascertain the long-term durability of coiled aneurysms completely occluded at 36 months' follow-up given the potential for delayed recanalization. METHODS: In this retrospective review, the authors examined 299 patients with 339 aneurysms, all shown to be completely occluded at 36 months on follow-up images obtained between 2011 and 2013. Medical records and radiological data acquired during the extended monitoring period (mean 74.3 ± 22.5 months) were retrieved, and the authors analyzed the incidence of (including mean annual risk) and risk factors for delayed recanalization. RESULTS: A total of 5 coiled aneurysms (1.5%) occluded completely at 36 months showed recanalization (0.46% per aneurysm-year) during the long-term surveillance period (1081.9 aneurysm-years), 2 surfacing within 60 months and 3 developing thereafter. Four showed minor recanalization, with only one instance of major recanalization. The latter involved the posterior communicating artery as an apparent de novo lesion, arising at the neck of a firmly coiled sac, and was unrelated to coil compaction or growth. Additional embolization was undertaken. In a multivariate analysis, a second embolization for a recurrent aneurysm (HR = 22.088, p = 0.003) independently correlated with delayed recanalization. CONCLUSIONS: Almost all coiled aneurysms (98.5%) showing complete occlusion at 36 months postembolization proved to be stable during extended observation. However, recurrent aneurysms were predisposed to delayed recanalization. Given the low probability yet seriousness of delayed recanalization and the possibility of de novo aneurysm formation, careful monitoring may be still considered in this setting but at less frequent intervals beyond 36 months.

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OBJECTIVE: The transsphenoidal route to pituitary adenomas challenges surgeons because of the highly variable sinunasal anatomy. Orientation may be improved if the appropriate information is provided intraoperatively by image guidance. The authors developed an advanced image guidance protocol dedicated to sinunasal surgery that extracts information from multiple modalities and forms it into a single image that includes fine sinunasal structures and arteries.The aim of this study was to compare the advantages of this novel image guidance protocol with the authors' previous series, with emphasis on anatomical structures visualized and complication rate. METHODS: This retrospective analysis comprised 200 patients who underwent surgery for pituitary adenoma via a transnasal transsphenoidal endoscopic approach. The authors' standard image guidance protocol consisting of CT for solid bone, T1CEMRI for soft tissues, and MRA for the carotid artery was applied in 100 consecutive cases. The advanced image guidance protocol added a first-hit ray casting of the CT scan for visualization of fine sinunasal structures, and adjustments to the MRA to visualize the sphenopalatine artery (SPA) were applied in a subsequent 100 consecutive cases. RESULTS: A patent sphenoid ostium-i.e., an ostium not covered by a mucosal layer-was visualized significantly more often by the advanced protocol than the standard protocol (89% vs 40%, p < 0.001) in primary surgeries. The SPA and its branches were only visualized by the advanced protocol (87% and 91% of cases in primary surgeries and reoperations, respectively) and not once by the standard protocol. The number of visualized complete and incomplete sphenoid septations matched significantly more commonly with the surgical view when using the advanced protocol than the standard protocol at primary operation (mean 1.9 vs 1.6, p < 0.001). However, in 25% of all cases a complex and not a simple sinus anatomy was present. In comparison with the intraoperative results, a complex sphenoid sinus anatomy was always detected by the advanced but not by the standard protocol (25% vs 8.5%, p = 0.001).Furthermore, application of the advanced protocol reduced the cumulative rate of complications (25% vs 18% [standard vs advanced group]). Although an overall significant difference could not be determined (p = 0.228), a subgroup analysis of reoperations (35/200) revealed a significantly lower rate of complications in the advanced group (5% vs 30%, p = 0.028). CONCLUSIONS: The data show that the advanced image guidance protocol could intraoperatively visualize the fine sinunasal sinus structures and small arteries with a high degree of detail. By improving intraoperative orientation, this may help to reduce the rate of complications in endoscopic transsphenoidal surgery, especially in reoperations.

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OBJECTIVEKawasaki disease (KD) is a vasculitis that can cause aneurysm formation in coronary arteries and, more rarely, in peripheral arteries. A possible connection between KD and intracranial aneurysms is unclear. The purpose of this study was to determine if KD is associated with intracranial aneurysms.METHODSIn this prospective cohort study, all patients hospitalized and diagnosed with KD in the authors' hospital district area in the period from 1978 to 1995 were identified. Patients with a current age ≥ 25 years and a history of KD in childhood were included in the study, which was conducted between 2016 and 2017. Magnetic resonance angiography (MRA) of the brain was performed in all patients.RESULTSForty patients (25 males), whose mean age was 33.5 ± 3.9 years (mean ± standard deviation), were eligible for study inclusion. The mean age at KD diagnosis was 3.9 ± 3.1 years, and the mean follow-up was 29.5 ± 4.3 years. Six patients (15%) had coronary arterial lesions during the acute illness of KD. None of the patients (0%) had intracranial aneurysms on brain MRA, which is significantly under the prevalence of 10% (95% CI 0%-8.8%, p = 0.03) that is the recommended limit for intracranial aneurysm screening.CONCLUSIONSThe study results suggest that KD is not associated with an increased prevalence of intracranial aneurysms and that screening for intracranial aneurysms is not warranted in patients with a history of KD.

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OBJECTIVEEffectively retaining the patency of the extracranial-intracranial (ECIC) bypass is one of the most important factors in improving long-term results; however, the factors influencing bypass patency have not been discussed much. Therefore, the authors investigated factors influencing the development of the bypass graft.METHODSIn this retrospective study, the authors evaluated 49 consecutive hemispheres in 47 adult Japanese patients who had undergone ECIC bypass for chronic steno-occlusive cerebrovascular disease. To evaluate objectively the development of the ECIC bypass graft, the change in the area of the main trunk portion of the superficial temporal artery (STA) from before to after bypass surgery (postop/preop STA) was measured. Using the interquartile range (IQR), the authors statistically analyzed the factors associated with excellent (> 3rd quartile) and poor development (< 1st quartile) of the bypass graft.RESULTSThe postop/preop STA ranged from 1.08 to 6.13 (median 1.97, IQR 1.645-2.445). There was a significant difference in the postop/preop STA between the presence and absence of concurrent diabetes mellitus (p = 0.0432) and hyperlipidemia (0.0069). Furthermore, logistic regression analysis revealed that only concurrent diabetes mellitus was significantly associated with poor development of the bypass graft (p = 0.0235).CONCLUSIONSDiabetes mellitus and hyperlipidemia influenced the development of the ECIC bypass graft. In particular, diabetes mellitus is the only factor associated with poor development of the bypass graft.

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OBJECTIVEPain relief following microvascular decompression (MVD) for trigeminal neuralgia (TN) may be related to pain type, degree of neurovascular conflict, arterial compression, and location of compression. The objective of this study was to construct a predictive pain-free scoring system based on clinical and radiographic factors that can be used to preoperatively prognosticate long-term outcomes for TN patients following surgical intervention (MVD or internal neurolysis [IN]). It was hypothesized that contributing factors would include pain type, presence of an artery or vein, neurovascular conflict severity, and compression location (root entry zone).METHODSAt the authors' institution 275 patients with type 1 or type 2 TN (TN1 or TN2) underwent MVD or IN following preoperative high-resolution brain MRI studies. Outcome data were obtained retrospectively by chart review and/or phone follow-up. Characteristics of neurovascular conflict were obtained from preoperative MRI studies. Factors that resulted in a probability value of < 0.05 on univariate logistic regression analyses were entered into a multivariate Cox regression analysis in a backward stepwise fashion. For the multivariate analysis, significance at the 0.15 level was used. A prognostic system was then devised with 4 possible scores (0, 1, 2, or 3) and pain-free survival analyses conducted.RESULTSUnivariate predictors of pain-free survival were pain type (p = 0.013), presence of any vessel (p = 0.042), and neurovascular compression severity (p = 0.038). Scores of 0, 1, 2, and 3 were found to be significantly different in regard to pain-free survival (log rank, p = 0.005). At 5 and 10 years there were 36%, 43%, 61%, and 69%, and 36%, 43%, 56%, and 67% pain-free survival rates in groups 0, 1, 2, and 3, respectively. While TN2 patients had worse outcomes regardless of score, a subgroup analysis of TN1 patients with higher neurovascular conflict (score of 3) had significantly better outcomes than TN1 patients without severe neurovascular conflict (score of 1) (log rank, p = 0.005). Regardless of pain type, those patients with severe neurovascular conflict were more likely to have arterial compression (99%) compared to those with low neurovascular conflict (p < 0.001).CONCLUSIONSPain-free survival was predicted by a scoring system based on preoperative clinical and radiographic findings. Higher scores predicted significantly better pain relief than lower scores. TN1 patients with severe neurovascular conflict had the best long-term pain-free outcome.

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OBJECTIVE: The purpose of this study is to present the authors' medium-term results, with special emphasis on complications, occlusion rate of the aneurysm sac (digital subtraction angiography [DSA] and MRI), and the fate of cortical branches and perforating arteries covered ("jailed") by the flow diverter (FD) stent. METHODS: Between January 2010 and September 2017, 29 patients (14 female) with 30 aneurysms were treated with an FD stent. Twenty-one aneurysms were at the middle cerebral artery bifurcation, 8 were in the anterior communicating artery region, and 1 was a pericallosal artery bifurcation. Thirty-five cortical branches were covered. A single FD stent was used in all patients. Symptomatic and asymptomatic periprocedural and delayed complications were reported. DSA and MRI controls were analyzed to evaluate modification of the aneurysm sac and jailed branches. RESULTS: Permanent morbidity was 3.4% (1/29), due to a jailed branch occlusion, with a modified Rankin Scale (mRS) score of 2 at the last follow-up. Mortality and permanent complication with poor prognosis (mRS score > 2) rates were 0%. The mean follow-up time for DSA and MRI (mean ± SD) was 21 ± 14.5 months (range 3-66 months) and 19 ± 16 months (range 3-41 months), respectively. The mean time to aneurysm sac occlusion (available for 24 patients), including stable remodeling, was 11.8 ± 6 months (median 13, range 3-27 months). The overall occlusion rate was 82.1% (23/28), and it was 91.7% (22/24) in the group of patients with at least 2 DSA control sequences. One recanalization occurred at 41 months posttreatment. At the time of publication, at the latest follow-up, 7 (20%) of 35 covered branches were occluded, 18 (51.4%) showed a decreased caliber, and the remaining 10 (28.5%) were unchanged. MRI T2-weighted sequences showed complete sac reabsorption in 7/29 aneurysms (24.1%), and the remaining lesions were either smaller (55.2%) or unchanged (17.2%). MRI revealed asymptomatic and symptomatic ischemic events in perforator territories in 7/28 (25%) and 4/28 (14.3%) patients, respectively, which were reversible within 24 hours. CONCLUSIONS: Flow diversion of bifurcation aneurysms is feasible, with low rates of permanent morbidity and mortality and high occlusion rates; however, recurrence may occur. Caliber reduction and asymptomatic occlusion of covered cortical branches as well as silent perforator stroke are common. Ischemic complications may occur with no identified predictable factors. MRI controls should be required in all patients to evaluate silent ischemic lesions and aneurysm sac reabsorption over time.

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OBJECTIVE: The relationship between intraplaque hypoxia and intraplaque hemorrhage (IPH) has been reported, but the details remain obscure. In this study, the authors aimed to clarify the relationship among intraplaque hypoxia, endothelial progenitor cells (EPCs), and neovascularization, which causes IPH. The histological findings of specimens obtained from carotid endarterectomy were assessed. METHODS: This study included 49 patients who underwent carotid endarterectomy. Magnetic resonance plaque imaging was performed to analyze the components of the carotid plaques, and surgical specimens were subjected to immunohistochemical analysis. The numbers of hypoxia-inducible factor-1 alpha (HIF-1α)-, CD34-, CD133-, and vascular endothelial growth factor receptor-2 (VEGFR-2)-positive cells in the carotid plaques were precisely quantified, as were the number and maximum diameter of CD31-positive microvessels. RESULTS: Plaque components were judged as fibrous in 7 samples, lipid-rich in 22, and IPH in 20. The number of CD34-, VEGFR-2-, and CD133-positive cells as an EPC-specific marker was significantly correlated with the number of HIF-1α-positive cells (r = 0.9, r = 0.82, and r = 0.81, respectively). These numbers varied among the 3 plaque components (IPH > lipid-rich > fibrous). The number and maximum luminal diameter of CD31-positive microvessels were also significantly correlated with the number of HIF-1α-positive cells (r = 0.85 and r = 0.89, respectively) and varied among the 3 plaque components (IPH > lipid-rich > fibrous). CONCLUSIONS: The present findings suggest that intraplaque hypoxia may accelerate abnormal microvessel formation derived from EPCs, which in turn promotes IPH. The results also suggest that microvessel enlargement is a pivotal characteristic of IPH and these enlarged microvessels are immature endothelial tubes with disorganized branching and are fragile and prone to rupture.

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OBJECTIVE: Recent MR vessel wall imaging studies have indicated intracranial aneurysms in the active state could show circumferential enhancement along the aneurysm wall (CEAW). While ruptured aneurysms frequently show CEAW, CEAW in unruptured aneurysms at the evolving state (i.e., growing or symptomatic) has not been studied in detail. The authors quantitatively assessed the degree of CEAW in evolving unruptured aneurysms by comparing it separately to that in stable unruptured and ruptured aneurysms. METHODS: A quantitative analysis of CEAW was performed in 26 consecutive evolving aneurysms using MR vessel wall imaging. Three-dimensional T1-weighted fast spin echo sequences were obtained before and after contrast media injection, and the contrast ratio of the aneurysm wall against the pituitary stalk (CRstalk) was calculated as the indicator of CEAW. Aneurysm characteristics of evolving aneurysms were compared with those of 69 stable unruptured and 67 ruptured aneurysms. RESULTS: The CRstalk values in evolving aneurysms were significantly higher than those in stable aneurysms (0.54 vs 0.34, p < 0.0001), and lower than those in ruptured aneurysms (0.54 vs 0.83, p < 0.0002). In multivariable analysis, CRstalk remained significant when comparing evolving with stable aneurysms (odds ratio [OR] 12.23, 95% confidence interval [CI] 3.53-42.41), and with ruptured aneurysms (OR 0.083, 95% CI 0.022-0.310). CONCLUSIONS: The CEAW in evolving aneurysms was higher than those in stable aneurysms, and lower than those in ruptured aneurysms. The degree of CEAW may indicate the process leading to rupture of intracranial aneurysms, which can be useful additional information to determine an indication for surgical treatment of unruptured aneurysms.

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OBJECTIVE: The cognitive deficits of vascular dementia and the vasoocclusive state of moyamoya disease have often been mimicked with bilateral stenosis/occlusion of the common carotid artery (CCA) or internal carotid artery. However, the cerebral blood flow (CBF) declines abruptly in these models after ligation of the CCA, which differs from "chronic" cerebral hypoperfusion. While some modified but time-consuming techniques have used staged occlusion of both CCAs, others used microcoils for CCA stenosis, producing an adverse effect on the arterial endothelium. Thus, the authors developed a new chronic cerebral hypoperfusion (CCH) model with cognitive impairment and a low mortality rate in rats. METHODS: Male Sprague-Dawley rats were subjected to unilateral CCA occlusion and contralateral induction of CCA stenosis (modified CCA occlusion [mCCAO]) or a sham operation. Cortical regional CBF (rCBF) was measured using laser speckle flowmetry. Cognitive function was assessed using a Barnes circular maze (BCM). MRI studies were performed 4 weeks after the operation to evaluate cervical and intracranial arteries and parenchymal injury. Behavioral and histological studies were performed at 4 and 8 weeks after surgery. RESULTS: The mCCAO group revealed a gradual CBF reduction with a low mortality rate (2.3%). White matter degeneration was evident in the corpus callosum and corpus striatum. Although the cellular density declined in the hippocampus, MRI revealed no cerebral infarctions after mCCAO. Immunohistochemistry revealed upregulated inflammatory cells and angiogenesis in the hippocampus and cerebral cortex. Results of the BCM assessment indicated significant impairment in spatial learning and memory in the mCCAO group. Although some resolution of white matter injury was observed at 8 weeks, the animals still had cognitive impairment. CONCLUSIONS: The mCCAO is a straightforward method of producing a CCH model in rats. It is associated with a low mortality rate and could potentially be used to investigate vascular disease, moyamoya disease, and CCH. This model was verified for an extended time point of 8 weeks after surgery.

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OBJECTIVE In microvascular decompression surgery for trigeminal neuralgia and hemifacial spasm, the bridging veins are dissected to provide the surgical corridors, and the veins of the brainstem may be mobilized in cases of venous compression. Strategy and technique in dissecting these veins may affect the surgical outcome. The authors investigated solutions for minimizing venous complications and reviewed the outcome for venous decompression. METHODS The authors retrospectively reviewed their surgical series of microvascular decompression for trigeminal neuralgia and hemifacial spasm in patients treated between 2005 and 2017. Surgical strategies included preservation of the superior petrosal vein and its tributaries, thorough dissection of the arachnoid sleeve that enveloped these veins, cutting of the inferior petrosal vein over the lower cranial nerves, and mobilization or cutting of the veins of the brainstem that compressed the nerve roots. The authors summarized the patient characteristics, operative findings, and postoperative outcomes according to the vascular compression types as follows: artery alone, artery and vein, and vein alone. They analyzed the data using chi-square and 1-way ANOVA tests. RESULTS The cohort was composed of 121 patients with trigeminal neuralgia and 205 patients with hemifacial spasm. The superior petrosal vein and its tributaries were preserved with no serious complications in all patients with trigeminal neuralgia. Venous compression alone and arterial and venous compressions were observed in 4% and 22%, respectively, of the patients with trigeminal neuralgia, and in 1% and 2%, respectively, of those with hemifacial spasm (p < 0.0001). In patients with trigeminal neuralgia, 35% of those with artery and venous compressions and 80% of those with venous compression alone had atypical neuralgia (p = 0.015). The surgical cure and recurrence rates of trigeminal neuralgias with venous compression were 60% and 20%, respectively, and with arterial and venous compressions the rates were 92% and 12%, respectively (p < 0.0001, p = 0.04). In patients with hemifacial spasm who had arterial and venous compressions, their recurrence rate was 60%, and that was significantly higher compared to other compression types (p = 0.0008). CONCLUSIONS Dissection of the arachnoid sleeve that envelops the superior petrosal vein may help to reduce venous complications in surgery for trigeminal neuralgia. Venous compression may correlate with worse prognosis even with thorough decompression, in both trigeminal neuralgia and hemifacial spasm.

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OBJECTIVE Patients with brain arteriovenous malformations (AVMs) often require repeat imaging with MRI or MR angiography (MRA), CT angiography (CTA), and digital subtraction angiography (DSA). The ideal imaging modality provides excellent vascular visualization without incurring added risks, such as radiation exposure. The purpose of this study is to evaluate the performance of ferumoxytol-enhanced MRA using a high-resolution 3D volumetric sequence (fe-SPGR) for visualizing and grading pediatric brain AVMs in comparison with CTA and DSA, which is the current imaging gold standard. METHODS In this retrospective cohort study, 21 patients with AVMs evaluated by fe-SPGR, CTA, and DSA between April 2014 and August 2017 were included. Two experienced raters graded AVMs using Spetzler-Martin criteria on all imaging studies. Lesion conspicuity (LC) and diagnostic confidence (DC) were assessed using a 5-point Likert scale, and interrater agreement was determined. The Kruskal-Wallis test was performed to assess the raters' grades and scores of LC and DC, with subsequent post hoc pairwise comparisons to assess for statistically significant differences between pairs of groups at p < 0.05. RESULTS Assigned Spetzler-Martin grades for AVMs on DSA, fe-SPGR, and CTA were not significantly different (p = 0.991). LC and DC scores were higher with fe-SPGR than with CTA (p < 0.05). A significant difference in LC scores was found between CTA and fe-SPGR (p < 0.001) and CTA and DSA (p < 0.001) but not between fe-SPGR and DSA (p = 0.146). A significant difference in DC scores was found among DSA, fe-SPGR, and CTA (p < 0.001) and between all pairs of the groups (p < 0.05). Interrater agreement was good to very good for all image groups (κ = 0.77-1.0, p < 0.001). CONCLUSIONS Fe-SPGR performed robustly in the diagnostic evaluation of brain AVMs, with improved visual depiction of AVMs compared with CTA and comparable Spetzler-Martin grading relative to CTA and DSA.

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OBJECTIVEThe choice of microvascular decompression (MVD), among the several other surgical options, for treating refractory classical trigeminal neuralgia (TN) relies mostly on preoperative imaging, but the degree of reliability of MRI remains a matter of debate. The authors approached the question of predictability of neurovascular conflict (NVC) in a series of 100 protocolized MRI studies from patients with TN who underwent MVD, by reexamination of MR images, blinded to the clinical data and surgical findings, including the side of the neuralgia.METHODSPatients included in the study were those who underwent MVD after surgical indication had been determined based on a protocolized imagery workup (3D high-resolution T2-weighted cisternography centered on the trigeminal nerve, 3D time-of-flight angiography, and 3D gadolinium-enhanced T1-weighted imaging) performed at our institution. All MR images were blindly reexamined, and neurovascular relationships were described on both sides, noting the existence of compression, vessels involved, situation along the root, and degree of compression. The results of MRI evaluation were then compared with actual surgical findings. The extent of agreement and quality of the prediction were expressed with Cohen's kappa coefficient (κ) and receiver operating characteristic (ROC) statistics.RESULTSA conflict had actually been found during surgery in 94 of 100 patients. The sensitivity of MRI to detect a conflict was 97% and the specificity was 50%. Vessel type was identified with high reliability (κ = 0.80), while the grade of the conflict and its situation along the root showed poor to average reliability (κ = 0.38 and κ = 0.40, respectively). The area under the ROC curve for predicting the presence of a conflict according to the grades of conflict seen on MRI was 0.93, which is considered very good. The positive predictive value was differentiated according to the grade of conflict, with a very high value for high grades of vascular conflict.CONCLUSIONSThis study shows an overall good reliability of MRI to predict the existence of an NVC. The prediction value is excellent for high grades of compression. Some apparent low-grade compressions on MRI may be revealed as false positives in surgical exploration. This raises the question of what other imaging methods might be used to determine not only the existence of a conflict but also its degree of compression. The degree of compression is of paramount importance to predict the probability of long-term pain relief, and therefore in the decision to propose MVD as the first choice of surgical treatment.

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OBJECTIVE: Aneurysm growth is considered predictive of future rupture of intracranial aneurysms. However, how accurately neuroradiologists can reliably detect incremental aneurysm growth using clinical MRI is still unknown. The purpose of this study was to assess the agreement rate of detecting aneurysm enlargement employing generally used MRI modalities. METHODS: Three silicone flow phantom models, each with 8 aneurysms of various sizes at different sites, were used in this study. The aneurysm models were identical except for an incremental increase in the sizes of the 8 aneurysms, which ranged from 0.4 mm to 2 mm. The phantoms were imaged on 1.5-T and 3-T MRI units with both time-of-flight (TOF) and contrast-enhanced MR angiography. Three independent expert neuroradiologists measured the aneurysms in a blinded manner using different measurement approaches. The individual and agreement detection rates of aneurysm enlargement among the 3 experts were calculated. RESULTS: The mean detection rate of any increase in any aneurysmal dimension was 95.7%. The detection rates of the 3 observers (observers A, B, and C) were 98.0%, 96.6%, and 92.7%, respectively (p = 0.22). The detection rates of each MRI modality were 91.3% using 1.5-T TOF, 97.2% using 1.5-T with Gd, 95.8% using 3.0-T TOF, and 97.2% using 3.0-T with Gd (p = 0.31). On the other hand, the mean detection rate for aneurysm enlargement was 54.8%. Specifically, the detection rates of observers A, B, and C were 49.0%, 46.1%, and 66.7%, respectively (p = 0.009). As the incremental enlargement value increased, the detection rate for aneurysm enlargement increased. The use of 1.5-T Gd improved the detection rate for small incremental enlargement (e.g., 0.4­1 mm) of the aneurysm (p = 0.04). The location of the aneurysm also affected the detection rate for aneurysm enlargement (p < 0.0001). CONCLUSIONS: The detection rate and interobserver agreement were very high for aneurysm enlargement of 0.4­2 mm. The detection rate for at least 1 increase in any aneurysm dimension did not depend on the choice of MRI modality or measurement protocol. Use of Gd improved the accuracy of measurement. Aneurysm location may influence the accuracy of detecting enlargement.

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Intracranial aneurysms in the neonate, presenting in the first 4 weeks of life, are exceedingly rare. They appear to have characteristics, including presentation and location, that vary from those found in adults. The authors present a case of a 28-day-old neonate with a ruptured distal middle cerebral artery (MCA) aneurysm. Initial noninvasive imaging with transfontanelle ultrasound and CT confirmed intraparenchymal and subarachnoid hemorrhage. Contrast-enhanced MRI revealed a 14-mm ruptured fusiform MCA aneurysm that was not identified on time-of-flight magnetic resonance angiography (MRA). Microsurgical treatment was performed with partial neurological recovery. A comprehensive review of the literature from 1949 to 2017 revealed a total of 40 aneurysms in 37 neonates, including the present case. The most common presenting symptom was seizure. Although subarachnoid hemorrhage was the most common form of hemorrhage, 40% had intraparenchymal hemorrhage. The median aneurysm size was 10 mm (range 2-30 mm) and the most common location was the MCA, with two-thirds of cases involving the distal intracranial vasculature. Over the last 10 years, there has been a trend of increasing noninvasive diagnosis of ruptured cerebral aneurysms in neonates, with CT angiography and contrast-enhanced MRI being the most useful diagnostic modalities. The use of contrast-enhanced MRI may improve sensitivity over time-of-flight MRA. Microsurgical treatment was the most common treatment modality overall, with increased use of endovascular treatment in the last decade. Most patients underwent microsurgical vessel ligation or endovascular parent vessel occlusion. There were high rates of neurological recovery after microsurgical or endovascular treatment, particularly for patients with distal aneurysms.

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OBJECTIVEIntracranial aneurysms are vascular abnormalities associated with neurological morbidity and mortality due to risk of rupture. In addition, many aneurysm treatments have associated risk profiles that can preclude the prophylactic treatment of asymptomatic lesions. Gamma Knife radiosurgery (GKRS) is a standard treatment for trigeminal neuralgia, tumors, and arteriovenous malformations. Aneurysms associated with arteriovenous malformations have been noted to resolve after treatment of the malformation. The aim of this study was to determine the efficacy of GKRS treatment in a saccular aneurysm animal model.METHODSAneurysms were surgically produced using an elastase-induced aneurysm model in the right common carotid artery of 10 New Zealand white rabbits. Following initial observation for 4 years, each rabbit aneurysm was treated with a conformal GKRS isodose of 25 Gy to the 50% margin. Longitudinal MRI studies obtained over 2 years and terminal measures obtained at multiple time points were used to track aneurysm size and shape index modifications.RESULTSAneurysms did not rupture or involute during the observation period. Whole aneurysm and blood volume averages decreased with a linear trend, at rates of 1.7% and 1.6% per month, respectively, over 24 months. Aneurysm wall percent volume increased linearly at a rate of 0.3% per month, indicating a relative thickening of the aneurysm wall during occlusion. Nonsphericity of the average volume, aspect ratio, and isoperimetric ratio of whole aneurysm volume all remained constant. Histopathological samples demonstrated progressive reduction in aneurysm size and wall thickening, with subintimal fibrosis. Consistent shape indices demonstrate stable aneurysm patency and maintenance of minimal rupture risk following treatment.CONCLUSIONSThe data indicate that GKRS targeted to saccular aneurysms is associated with histopathological changes and linear reduction of aneurysm size over time. The results suggest that GKRS may be a viable, minimally invasive treatment option for intracranial aneurysm obliteration.

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OBJECTIVE Clival epidural-osseous dural arteriovenous fistula (DAVF) is often associated with a large nidus, multiple arterial feeders, and complex venous drainage. In this study the authors report the outcomes of clival epidural-osseous DAVFs treated using Gamma Knife surgery (GKS). METHODS Thirteen patients with 13 clival epidural-osseous DAVFs were treated with GKS at the authors' institution between 1993 and 2015. Patient age at the time of GKS ranged from 38 to 76 years (median 55 years). Eight DAVFs were classified as Cognard Type I, 4 as Type IIa, and 1 as Type IIa+b. The median treatment volume was 17.6 cm3 (range 6.2-40.3 cm3). The median prescribed margin dose was 16.5 Gy (range 15-18 Gy). Clinical and radiological follow-ups were performed at 6-month intervals. Patient outcomes after GKS were categorized as 1) complete improvement, 2) partial improvement, 3) stationary, and 4) progression. RESULTS All 13 patients demonstrated symptomatic improvement, and on catheter angiography 12 of the 13 patients had complete obliteration and 1 patient had partial obliteration. The median follow-up period was 26 months (range 14-186 months). The median latency period from GKS to obliteration was 21 months (range 8-186 months). There was no intracranial hemorrhage during the follow-up period, and no deaths occurred. Two adverse events were observed following treatment, and 2 patients required repeat GKS treatment with eventual complete obliteration. CONCLUSIONS Gamma Knife surgery offers a safe and effective primary or adjuvant treatment modality for complex clival epidural-osseous DAVFs. All patients in this case series demonstrated symptomatic improvement, and almost all patients attained complete obliteration.

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OBJECTIVE Case selection for the surgical treatment of brain arteriovenous malformations (BAVMs) remains challenging. This study aimed to construct a predictive grading system combining lesion-to-eloquence distance (LED) for selecting patients with BAVMs for surgery. METHODS Between September 2012 and September 2015, the authors retrospectively studied 201 consecutive patients with BAVMs. All patients had undergone preoperative functional MRI and diffusion tensor imaging (DTI), followed by resection. Both angioarchitectural factors and LED were analyzed with respect to the change between preoperative and final postoperative modified Rankin Scale (mRS) scores. LED refers to the distance between the lesion and the nearest eloquent area (eloquent cortex or eloquent fiber tracts) measured on preoperative fMRI and DTI. Based on logistic regression analysis, the authors constructed 3 new grading systems. The HDVL grading system includes the independent predictors of mRS change (hemorrhagic presentation, diffuseness, deep venous drainage, and LED). Full Score combines the variables in the Spetzler-Martin (S-M) grading system (nidus size, eloquence of adjacent brain, and venous drainage) and the HDVL. For the third grading system, the fS-M grading system, the authors added information regarding eloquent fiber tracts to the S-M grading system. The area under the receiver operating characteristic (ROC) curves was compared with those of the S-M grading system and the supplementary S-M grading system of Lawton et al. RESULTS LED was significantly correlated with a change in mRS score (p < 0.001). An LED of 4.95 mm was the cutoff point for the worsened mRS score. Hemorrhagic presentation, diffuseness, deep venous drainage, and LED were independent predictors of a change in mRS score. Predictive accuracy was highest for the HDVL grading system (area under the ROC curve 0.82), followed by the Full Score grading system (0.80), the fS-M grading system (0.79), the supplementary S-M grading system (0.76), and least for the S-M grading system (0.71). Predictive accuracy of the HDVL grading system was significantly better than that of the Spetzler-Martin grade (p = 0.040). CONCLUSIONS LED was a significant predictor for the preoperative risk evaluation for surgery. The HDVL system was a good predictor of neurological outcomes after BAVM surgery. Adding the consideration of the involvement of eloquent fiber tracts to preoperative evaluation can effectively improve its predictive accuracy.

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