BACKGROUND AND PURPOSE:In patients with Moyamoya disease, the relationship between preoperative hemodynamic status and prognosis after encephalo-duro-arterial synangiosis (EDAS) surgery was unclear. We aimed to explore the value of the preoperative hemodynamic status acquired by cine phase-contrast MR imaging in predicting collateral formation and clinical outcomes after EDAS surgery in patients with Moyamoya disease.

BackgroundLittle is known about the association between stroke and imaging and clinical features in conservatively treated patients with moyamoya disease (MMD).PurposeTo investigate independent risk factors for stroke in conservatively treated patients with MMD during a long‐term follow‐up.Study TypeProspective study.SubjectsOne hundred sixty conservatively managed patients with MMD (median age 46 years, 89 male).Field Strength/SequenceTime of flight, turbo inversion recovery magnitude T1WI, turbo spin echo (TSE) T2WI, echo‐planar imaging DWI, T2‐fluid attenuated inversion recovery, dynamic susceptibility contrast‐magnetic resonance imaging, and pre‐ and post‐contrast 3D TSE T1WI sequences at 3.0 Tesla.AssessmentPatients were assessed at baseline and followed yearly. Ischemic and hemorrhagic stroke incidence rates were determined. Multiple demographic, clinical (modified Rankin score [mRS]), and cerebral imaging (cerebral blood volume [CBV] and concentric enhancement of arterial wall) factors at baseline were considered as potential predictors of stroke during the follow‐up period.Statistical TestsUnivariable and multivariable Cox proportional hazards models to calculate the hazard ratios (HRs) and corresponding 95% confidence interval (CI) for stroke. Cumulative risk of stroke was estimated by the Kaplan–Meier product‐limit method. A P value <0.05 was considered statistically significant.ResultsThe median follow‐up duration was 47 months. During the follow‐up period, 18 (11.25%) patients experienced stroke events (13 [8.13%] ischemic, 5 [3.12%] hemorrhagic). Univariable analysis showed that 11 factors were significantly associated with stroke. After adjustment for clinical characteristics, multivariable analysis showed that mRS score ≥3 (HR, 1.99; 95% CI, 1.26–3.14), decreased CBV (HR, 5.31; 95% CI, 2.32–12.13), and concentric enhancement of the arterial wall (HR, 4.16; 95% CI, 1.55–11.15) were significantly associated with stroke.Data ConclusionDecreased CBV, mRS score ≥ 3, and concentric enhancement of the arterial wall were significantly associated with increased incidence of stroke in conservatively treated MMD.Evidence Level2Technical EfficacyStage 4

Fast IP flow rate estimation has many potential applications in network management, monitoring, security, and traffic engineering. Recently, low cost and memory efficient techniques to accurately estimate flow-rates in real-time have been developed. These techniques rely on flow definitions being constrained to being subsets of the fields in the packet header making flow-membership tests relatively inexpensive. In this paper, we consider a more general flow-rate estimation problem where flow membership testing is non-trivial and may involve more complex processing such as packet-payload based tests. An example is to estimate the amount of traffic that contains a given set of patterns (e.g., virus or worm signatures). We design new flow estimation techniques to reduce the number of membership tests. These techniques track pairs of arrivals that have the given property of interest and use lazy membership testing to avoid complex property testing unless absolutely necessary. The efficiency of the new schemes is evaluated by both analysis and simulation.