An evaluation of resonant scanning as a high-speed imaging technique for two-photon imaging of cortical vasculature

We demonstrate a simple, low-cost two-photon microscope design with both galvo-galvo and resonant-galvo scanning capabilities. We quantify and compare the signal-to-noise ratios and imaging speeds of the galvo-galvo and resonant-galvo scanning modes when used for murine neurovascular imaging. The two scanning modes perform as expected under shot-noise limited detection and are found to achieve comparable signal-to-noise ratios. Resonant-galvo scanning is capable of reaching desired signal-to-noise ratios using less acquisition time when higher excitation power can be used. Given equal excitation power and total pixel dwell time between the two methods, galvo-galvo scanning outperforms resonant-galvo scanning in image quality when detection deviates from being shot-noise limited.

Diagnostic and Therapeutic Challenges of Cerebral Venous Thrombosis in SARS-CoV-2 Infection: A Case Report and Review of Literature

Headache, a common prodromal symptom of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, can also be a manifestation of cerebral venous thrombosis (CVT), secondary to COVID-19. CVT management continues to evolve, with direct oral anticoagulants (DOACs) emerging as an alternative to warfarin. A 44-year-old Asian female, with no past medical history, presented to the emergency room (ER) with complaints of nonproductive cough and left-sided headache. She denied a history of COVID-19 vaccination, and SARS-CoV-2 testing (with reverse transcriptase-polymerase chain reaction) was positive. Non-contrast computed tomography (CT) of the head revealed left transverse sinus hyperdensity, consistent with dense vein sign, and magnetic resonance venography (MRV) confirmed the presence of thrombus. The initial treatment included subcutaneous enoxaparin with headache resolution, and she was discharged on apixaban. Five weeks later, a non-contrast head CT showed resolution of the dense vein sign and recanalisation of left transverse sinus was seen on MRV. This report has highlighted the need for increased awareness of coagulopathy and thrombotic events, including cerebral venous thrombosis, in patients infected with SARS-CoV-2. Unremitting headache, in context of SARS-CoV-2 infection, should be evaluated with appropriate neurovascular imaging. Controlled studies are required to compare the safety and efficacy of DOACs with warfarin for management of cerebral venous thrombosis.

Neurovascular imaging with QUTE-CE MRI in APOE4 rats reveals early vascular abnormalities

Cerebrovascular abnormality is linked to Alzheimer’s disease and related dementias (ADRDs). ApoE-Ɛ4 (APOE4) is known to play a critical role in neurovascular dysfunction, however current medical imaging technologies are limited in quantification. This cross-sectional study tested the feasibility of a recently established imaging modality, quantitative ultra-short time-to-echo contrast-enhanced magnetic resonance imaging (QUTE-CE MRI), to identify small vessel abnormality early in development of human APOE4 knock-in female rat (TGRA8960) animal model. At 8 months, 48.3% of the brain volume was found to have significant signal increase (75/173 anatomically segmented regions; q<0.05 for multiple comparisons). Notably, vascular abnormality was detected in the tri-synaptic circuit, cerebellum, and amygdala, all of which are known to functionally decline throughout AD pathology and have implications in learning and memory. The detected abnormality quantified with QUTE-CE MRI is likely a result of hyper-vascularization, but may also be partly, or wholly, due to contributions from blood-brain-barrier leakage. Further exploration with histological validation is warranted to verify the pathological cause. Regardless, these results indicate that QUTE-CE MRI can detect neurovascular dysfunction with high sensitivity with APOE4 and may be helpful to provide new insights into health and disease.

Lacunar stroke: mechanisms and therapeutic implications

Lacunar stroke is a marker of cerebral small vessel disease and accounts for up to 25% of ischaemic stroke. In this narrative review, we provide an overview of potential lacunar stroke mechanisms and discuss therapeutic implications based on the underlying mechanism. For this paper, we reviewed the literature from important studies (randomised trials, exploratory comparative studies and case series) on lacunar stroke patients with a focus on more recent studies highlighting mechanisms and stroke prevention strategies in patients with lacunar stroke. These studies suggest that lacunar stroke is a heterogeneous disease with various mechanisms, including most commonly lipohyalinosis and less commonly atheromatous disease and cardioembolism, highlighting the importance of a careful review of brain and neurovascular imaging, a cardiac and systemic evaluation. A better understanding of pathomechanisms of neurological deterioration may lead to investigating the utility of novel treatment strategies and optimisation of short-term antithrombotic treatment strategies to reduce the risk of neurological deterioration and prevent long-term disability in patients with lacunar stroke.

Arteriopathy in pediatric stroke: an underestimated clinical entity

ABSTRACT Background: Pediatric arterial ischemic stroke (AIS), which was thought to be a rare disorder, is being increasingly recognized as an important cause of neurological morbidity, thanks to new advances in neuroimaging. Objective: The aim of this study was to review the main etiologies of stroke due to arteriopathy in children. Methods: Using a series of cases from our institution, we addressed its epidemiological aspects, physiopathology, imaging findings from CT, MR angiography, MR conventional sequences and MR DWI, and nuclear medicine findings. Results: Through discussion of the most recent classification for childhood AIS (Childhood AIS Standardized Classification and Diagnostic Evaluation, CASCADE), we propose a modified classification based on the anatomical site of disease, which includes vasculitis, varicella, arterial dissection, moyamoya, fibromuscular dysplasia, Takayasu's arteritis and genetic causes (such as ACTA-2 mutation, PHACE syndrome and ADA-2 deficiency). We have detailed each of these separately. Conclusions: Prompt recognition of AIS and thorough investigation for potential risk factors are crucial for a better outcome. In this scenario, neurovascular imaging plays an important role in diagnosing AIS and identifying children at high risk of recurrent stroke.

Abstract P298: Redundant Imaging in TIA: Evidence From the Nationwide Emergency Department Sample (NEDS)

Introduction: Multiple societal guidelines recommend patients with TIA be emergently imaged with brain-MRI and neurovascular screening-CTA, MRA or carotid ultrasound-to identify and treat risk factors for future stroke. Increased ED compliance with TIA imaging guidelines has previously been demonstrated, along with a substantial increase in imaging utilization over the past decade. The purpose of this study was to quantify prevalence of redundant imaging during ED work-up of TIA, and to identify imaging practices that could be targeted to reduce unnecessary expenditures. Methods: Utilizing the 2006-2017 Nationwide Emergency Department Sample, patients discharged with TIA from EDs in the US were identified using ICD-9/10 codes. Brain and neurovascular imaging obtained during the encounter was identified using CPT codes. Demographics, payor, patient income, and hospital characteristics were incorporated into a hierarchical multivariable logistic regression analysis to identify significant associations with redundant neuroimaging. Results: In 2017 there were 184,870 patients discharged from EDs with TIA. Redundant brain, brain vascular, and cervical vascular imaging was identified in 55,513(30%), 5,149(2.8%) and 1,325(0.7%) of encounters respectively. Decreased odds of obtaining redundant neuroimaging in a TIA encounter was observed in Medicaid patients(OR:0.72, 95%CI:0.64-0.81), non-trauma centers(OR:0.49, 95%CI:0.26-0.93), rural hospital locations(OR:0.18, 95%CI:0.11-0.29) and weekend encounters(OR:0.9, 95%CI:0.85-0.96). Trend analysis from 2006 to 2017 demonstrated a rise in redundant brain and neurovascular imaging from 2.3% and 0.2% of encounters respectively in 2006 to 30% and 3.5% of encounters in 2017. Using Medicare fee estimates, in 2017 redundant brain and neurovascular imaging for patients discharged from EDs with TIA resulted in additional charges of approximately 8,670,832 USD. Conclusion: Increasing utilization of imaging for workup of TIA across EDs in the US is also associated with substantial and increasing use of redundant imaging. We identify redundant brain and neurovascular imaging as areas that could be targeted to mitigate rising imaging expenditures.