Key Points Question What are the characteristics of amyloid-related imaging abnormalities (ARIA) during aducanumab treatment in individuals with early Alzheimer disease? Findings In an integrated safety data set of 2 phase 3 clinical trials (EMERGE and ENGAGE) including 3285 participants, 425 patients (41.3%) in the combined 10 mg/kg aducanumab group (n = 1029) experienced ARIA; ARIA-edema occurred in 362 patients (35.2%), and 94 of these patients (26.0%) experienced associated symptoms (eg, headache, confusion, dizziness, and nausea). ARIA-microhemorrhage and ARIA–superficial siderosis occurred in 197 patients (19.1%) and 151 patients (14.7%), respectively. Meaning Amyloid-related imaging abnormalities occurred in approximately 40% of participants in the phase 3 studies of aducanumab, and approximately one-quarter of these patients experienced symptoms.

Routine measurement of the cochlear height and bony island of the lateral semicircular canal, in conjunction with visual inspection of CT images, will increase recognition of common inner ear malformations.

Purpose:To establish the feasibility of intracranial timeof-flight (TOF) MR angiography (MRA) at 7T using phased array coils and to compare its performance to 3T. Materials and Methods:In an initial study, five normal volunteers were scanned at 7T and 3T using eight-channel coils and standard acquisition parameters from a clinical TOF protocol. In a second study three additional studies were performed at 7T and 3T using empirically optimized 7T parameters. Contrast-to-noise (CNR) values were measured for major vessel segments.Results: All measurements documented CNR increases at 7T, with a mean increase of 83% in the initial study and 88% in the second study. The CNR values achieved using the latter protocol were similar to the values obtained in the initial study, despite the 42% reduction expected due to the higher spatial resolution. CNR in the smaller peripheral vessels was increased dramatically, resulting in excellent visualization at high resolution. Conclusion:TOF MRA at 7T demonstrated improved visualization of the intracranial vasculature, particularly the smaller peripheral vessels, and may benefit studies of small aneurysms, atherosclerosis, vasospasm, and vasculitis.

Amyloid positron emission tomography (PET) imaging is being investigated as a screening tool to identify amyloid-positive patients as an enrichment strategy for Alzheimer disease (AD) clinical trial enrollment. In a multicenter, phase 1b trial, patients meeting clinical criteria for prodromal or mild AD underwent florbetapir PET scanning at screening. PET, magnetic resonance imaging, and coregistered PET/magnetic resonance imaging scans were reviewed by 2 independent readers and binary visual readings tabulated. Semiquantitative values of cortical to whole cerebellar standard uptake value ratios were computed (threshold 1.10). Of 278 patients with an evaluable PET scan, 170 (61%) and 185 (67%) were amyloid-positive by visual reading and quantitative analysis, respectively; 39% were excluded from the study due to an amyloid-negative scan based on visual readings. More ApoE ε4 carriers than noncarriers were amyloid-positive (80% vs. 43%). Comparison of visual readings with quantitative results identified 21 discordant cases (92% agreement). Interreader and intrareader agreements from visual readings were 98% and 100%, respectively. Amyloid PET imaging is an effective and feasible screening tool for enrollment of amyloid-positive patients with early stages of AD into clinical trials.

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ARIA was detected more often on MRI scans when every scan was reviewed by trained neuroradiologists and results adjudicated. There was increased incidence of ARIA-E in bapineuzumab-treated carriers who had a microhemorrhage at baseline. ARIA-E was a risk factor for incident ARIA-H and late onset ARIA-E was milder radiologically. Age-related white matter changes did not progress during the study.

SUMMARY: allows for the acquisition of dynamic, multidirectional data on blood flow and has recently been used for the evaluation of intracranial arterial flow. Using a 3T system with optimization of both temporal resolution and k-space subsampling with a combination of parallel imaging and cut-corner acquisition, we present the clinical assessment of a patient with an arteriovenous malformation by providing complete intracranial arterial and venous coverage in a reasonable scan time. Phase-contrast MR imaging enables the acquisition of multidirectional blood velocity data. With time-resolved, 3D phase-contrast MR imaging (4D Flow), electrocardiographic gating is used to create cine volumetric data. The technique has been most extensively used for the evaluation of patterns of blood flow in the thoracic aorta, including characterization of abnormal flow patterns associated with pathologic disorders such as ascending aortic aneurysm and dissection.1,2 Recent studies have explored the use of 4D Flow imaging for other areas of vascular anatomy and pathology, including intracranial arterial blood flow. [3][4][5] We have furthered these efforts toward clinical neurovascular imaging by modifying the 4D Flow technique with the goal of complete intracranial arterial and venous coverage to provide clinical assessment of a patient with an arteriovenous malformation (AVM).Detailed evaluation of the arterial inflow and venous drainage of AVMs is important for clinical evaluation and management. 6 The use of 4D Flow may aid characterization of the pattern and distribution of feeding arteries by quantification of the relative blood flow through vessels of interest. In a similar fashion, 4D Flow could be useful for the evaluation of venous anatomy, with the additional benefit of identification of venous stenoses as regions of local acceleration of venous blood flow as well as areas at risk for wall shear stress-induced pathologic processes. Stenosis of high-flow draining veins is thought to induce a redistribution of blood flow within an AVM nidus, causing a hemodynamic overload and, consequently, an increased risk for rupture. 7 In addition, 4D Flow may be of benefit in conjunction with endovascular procedures or stereotactic radiation to assess changes in relative blood flow entering and exiting an AVM status postintervention. Previous work with animal models has demonstrated that arterial characteristics of venous drainage from AVMs, including pulsatility, high peak velocities, and a larger difference between maximum and minimum velocities, are significantly reduced after successful intervention. 8Lengthy scan time has been a limitation of neurovascular 4D Flow. Even with the limited spatial acquisitions described in previous studies (ie, slab thickness less than 5 cm), scan times often exceeded 20 minutes. Given our goal of a clinically feasible whole-brain arterial and venous 4D Flow acquisition, the reduction of scan time was of central importance. We have optimized the 3 possibilities available to us to limit scan time:...