A case of recurrent aneurysm resulting from dual antiplatelet plus anticoagulation after confirmed aneurysm closure following coil-assisted flow diversion.

Dual antiplatelet therapy (DAPT) is a management cornerstone for intracranial aneurysms treated with flow diversion. However, combined dual antiplatelet plus anticoagulation (triple therapy) can be indicated in some patients with important associated risks. Here we present the case of a 72-year-old woman with prior history of subarachnoid hemorrhage who was started on triple therapy (enoxaparin and DAPT) following successful flow diversion of an enlarging but unruptured left fetal posterior communicating artery aneurysm. Her post-procedural course was complicated by in-stent thrombosis in the setting of a missed ticagrelor dose and subsequent development of deep venous thrombosis and pulmonary embolism. An early follow-up angiogram confirmed occlusion of the aneurysm. However, after initiation of triple therapy, the aneurysm partially recanalized and her symptoms recurred. Subsequent discontinuation of enoxaparin lead to prompt aneurysm re-occlusion. To our knowledge, this is the first reported instance of confirmed intra-aneurysmal thrombolysis in a successfully treated aneurysm after triple therapy initiation.

Anatomy of the Intracranial Arteries: The Internal Carotid Artery.

The internal carotid artery is an elegant vessel that is segmentally defined by adjacent anatomic landmarks and defined branch vasculature. Here we describe the segmental and branch angiographic anatomy of the internal carotid artery with particular regard to embryologic development, clinically important anastomotic pathways, and cerebrovascular diseases, such as aneurysm development.

Anatomy of the Intracranial Arteries: The Anterior Intracranial and Vertebrobasilar Circulations.

The intracranial vasculature, separated into the anterior and posterior circulations, constitute an elegant and complex cerebrovascular bed providing redundant supply to the brain. Here the authors present an anatomic framework for understanding the segmental and branch anatomy, clinically important anastomotic pathways, and pathology of the intracranial arterial system with a focus on angiographic definition.

Non-contrast dual-energy CT virtual ischemia maps accurately estimate ischemic core size in large-vessel occlusive stroke.

Dual-energy CT (DECT) material decomposition techniques may better detect edema within cerebral infarcts than conventional non-contrast CT (NCCT). This study compared if Virtual Ischemia Maps (VIM) derived from non-contrast DECT of patients with acute ischemic stroke due to large-vessel occlusion (AIS-LVO) are superior to NCCT for ischemic core estimation, compared against reference-standard DWI-MRI. Only patients whose baseline ischemic core was most likely to remain stable on follow-up MRI were included, defined as those with excellent post-thrombectomy revascularization or no perfusion mismatch. Twenty-four consecutive AIS-LVO patients with baseline non-contrast DECT, CT perfusion (CTP), and DWI-MRI were analyzed. The primary outcome measure was agreement between volumetric manually segmented VIM, NCCT, and automatically segmented CTP estimates of the ischemic core relative to manually segmented DWI volumes. Volume agreement was assessed using Bland-Altman plots and comparison of CT to DWI volume ratios. DWI volumes were better approximated by VIM than NCCT (VIM/DWI ratio 0.68 ± 0.35 vs. NCCT/DWI ratio 0.34 ± 0.35; P < 0.001) or CTP (CTP/DWI ratio 0.45 ± 0.67; P < 0.001), and VIM best correlated with DWI (rVIM = 0.90; rNCCT = 0.75; rCTP = 0.77; P < 0.001). Bland-Altman analyses indicated significantly greater agreement between DWI and VIM than NCCT core volumes (mean bias 0.60 [95%AI 0.39-0.82] vs. 0.20 [95%AI 0.11-0.30]). We conclude that DECT VIM estimates the ischemic core in AIS-LVO patients more accurately than NCCT.

Image Quality of Virtual Monochromatic Reconstructions of Noncontrast CT on a Dual-Source CT Scanner in Adult Patients.

RATIONALE AND OBJECTIVES: To evaluate the image quality of virtual monochromatic images (VMI) reconstructed from dual-energy dual-source noncontrast head CT with different reconstruction kernels. MATERIALS AND METHODS: Twenty-five consecutive adult patients underwent noncontrast dual-energy CT. VMI were retrospectively reconstructed at 5-keV increments from 40 to 140 keV using quantitative and head kernels. CT-number, noise levels (SD), signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) in the gray and white matter and artifacts using the posterior fossa artifact index (PFAI) were evaluated. RESULTS: CT-number increased with decreasing VMI energy levels, and SD was lowest at 85 keV. SNR was maximized at 80 keV and 85 keV for the head and quantitative kernels, respectively. CNR was maximum at 40 keV; PFAI was lowest at 90 (head kernel) and 100 (quantitative kernel) keV. Optimal VMI image quality was significantly better than conventional CT. CONCLUSION: Optimal image quality of VMI energies can improve brain parenchymal image quality compared to conventional CT but are reconstruction kernel dependent and depend on indication for performing noncontrast CT.

Virtual monochromatic dual-energy CT reconstructions improve detection of cerebral infarct in patients with suspicion of stroke.

PURPOSE: Early infarcts are hard to diagnose on non-contrast head CT. Dual-energy CT (DECT) may potentially increase infarct differentiation. The optimal DECT settings for differentiation were identified and evaluated. METHODS: One hundred and twenty-five consecutive patients who presented with suspected acute ischemic stroke (AIS) and underwent non-contrast DECT and subsequent DWI were retrospectively identified. The DWI was used as reference standard. First, virtual monochromatic images (VMI) of 25 patients were reconstructed from 40 to 140 keV and scored by two readers for acute infarct. Sensitivity, specificity, positive, and negative predictive values for infarct detection were compared and a subset of VMI energies were selected. Next, for a separate larger cohort of 100 suspected AIS patients, conventional non-contrast CT (NCT) and selected VMI were scored by two readers for the presence and location of infarct. The same statistics for infarct detection were calculated. Infarct location match was compared per vascular territory. Subgroup analyses were dichotomized by time from last-seen-well to CT imaging. RESULTS: A total of 80-90 keV VMI were marginally more sensitive (36.3-37.3%) than NCT (32.4%; p > 0.680), with marginally higher specificity (92.2-94.4 vs 91.1%; p > 0.509) for infarct detection. Location match was superior for VMI compared with NCT (28.7-27.4 vs 19.5%; p < 0.010). Within 4.5 h from last-seen-well, 80 keV VMI more accurately detected infarct (58.0 vs 54.0%) and localized infarcts (27.1 vs 11.9%; p = 0.004) than NCT, whereas after 4.5 h, 90 keV VMI was more accurate (69.3 vs 66.3%). CONCLUSION: Non-contrast 80-90 keV VMI best differentiates normal from infarcted brain parenchyma.

Early Head Computed Tomography Abnormalities Associated with Elevated Intracranial Pressure in Severe Traumatic Brain Injury.

BACKGROUND AND PURPOSE: Intracranial pressure (ICP) monitoring is recommended in severe traumatic brain injury (sTBI), yet invasive monitoring has risks, and many patients do not develop elevated ICP. Tools to identify patients at risk for ICP elevation are limited. We aimed to identify early radiologic biomarkers of ICP elevation. METHODS: In this retrospective study, we analyzed a prospectively enrolled cohort of patients with a sTBI at an academic level 1 trauma center. Inclusion criteria were nonpenetrating TBI, age ≥16 years, Glasgow Coma Scale (GCS) score ≤8, and presence of an ICP monitor. Two independent reviewers manually evaluated 30 prespecified features on serial head computed tomography (CTs). Patient characteristics and radiologic features were correlated with elevated ICP. The primary outcome was clinically relevant ICP elevation, defined as ICP ≥ 20 mm Hg on at least 5 or more hourly recordings during postinjury days 0-7 with concurrent administration of an ICP-lowering treatment. RESULTS: Among 111 sTBI patients, the median GCS was 6 (interquartile range 3-8), and 45% had elevated ICP. Features associated with elevated ICP were younger age (every 10-year decrease, odds ratio [OR] 1.4), modified Fisher scale (mFS) score at 0-4 hours postinjury (every 1 point, OR 1.8), and combined volume of contusional hemorrhage and peri-hematoma edema (10 ml, OR 1.2) at 4-18 hours postinjury. CONCLUSIONS: Younger age, mFS score, and volume of contusion are associated with ICP elevation in patients with a sTBI. Imaging features may stratify patients by their risk of subsequent ICP elevation.

Hypoperfusion Intensity Ratio Predicts Malignant Edema and Functional Outcome in Large-Vessel Occlusive Stroke with Poor Revascularization.

BACKGROUND AND OBJECTIVE: Malignant cerebral edema (MCE) is a well-known complication in patients with acute ischemic stroke with core infarcts ≥ 80 mL caused by large-vessel occlusions. MCE can also develop in patients with smaller infarcts with moderate -to-large volume of tissue at risk who do not achieve successful revascularization with endovascular thrombectomy (ET). Features that predict the development of MCE in this population are not well-described. We aim to identify predictors of MCE and 90-day functional outcome in stroke patients with an anterior circulation large vessel occlusion (LVO) and a < 80 mL ischemic core who do not achieve complete reperfusion. METHODS: We reviewed our institutional stroke registry and included patients who achieved unsuccessful revascularization, mTICI 0-2a, after ET and whose baseline imaging was notable for a core infarct < 80 mL, a Tmax > 6 s volume ≥ 80 mL, and a mismatch ratio ≥ 1.8. MCE was defined as ≥ 5 mm of midline shift on follow-up imaging, obtained 6-48 h after the pre-ET perfusion scan. RESULTS: Thirty-six patients met inclusion criteria. Unadjusted analysis demonstrated that younger age, higher systolic blood pressure, larger core volume, and higher hypoperfusion intensity ratio (HIR) were associated with MCE (all p < 0.02). In multivariate logistic regression analysis, age, HIR, and core infarct volume were independent predictors of MCE. The optimal HIR threshold to predict MCE was ≥ 0.54 (OR 14.7, 95% CI 2.4-78.0, p = 0.003). HIR was also associated with 3-month mRS (HIR ≥ 0.54 for mRS of 3-6: OR 10.8, 95% CI 1.9-44.0, p = 0.02). CONCLUSIONS: Younger age, larger core infarct volume, and higher HIR are predictive of MCE in patients with anterior circulation LVO, moderate-to-large tissue at risk, and suboptimal revascularization. HIR is correlated with three-month functional outcomes.

Endovascular Treatment of Acute Carotid Stent Occlusion: Aspiration Thrombectomy and Angioplasty.

Introduction Acute carotid stent occlusion (CSO) is a rare complication of endovascular carotid stent placement that requires emergent intervention. We describe angioplasty or combined angioplasty and aspiration thrombectomy as a new endovascular technique for CSO treatment. The technique is compared to others previously described in the literature. Methods We performed a retrospective cohort study of all patients who underwent endovascular treatment (ET) of acute symptomatic CSO from January 2008 to March 2018 at our neurovascular referral center. Patient demographics, endovascular treatment details, and outcome data were determined from the electronic medical record. Primary outcome was successful stent recanalization and cerebral reperfusion (modified thrombolysis in cerebral infarction (mTICI) score IIB-III). Secondary outcomes were National Institutes of Health Stroke Scale (NIHSS) shift from presentation to discharge, mortality, and modified Rankin Scale (mRS) score at 3 months. Additionally, a literature review (years 2008-2019) was performed to characterize other techniques for ET of CSO. Results Four patients who underwent ET of acute CSO were identified. ET treatment by angioplasty (n = 1) or combined aspiration thrombectomy and angioplasty (n = 3) resulted in carotid stent recanalization in all patients. Tandem intracranial occlusions were present in three patients (75%), and successful cerebral reperfusion was achieved in all patients. Patient symptoms improved (mean NIHSS shift -5.3 ± 7.2 at discharge). One patient died of a symptomatic reperfusion hemorrhage and another died of cardiac complications by 3-month follow-up. The mRS scores of the surviving patients were 1 and 3. Previously described studies (n = 14) using different and varied techniques had moderate recanalization rates and outcomes. Conclusion Combined aspiration thrombectomy and angioplasty for the neurointerventional treatment of acute CSO leads to high rates of stent recanalization and cerebral reperfusion. The recanalization rate here is improved compared to previously reported techniques. Further multicenter studies are required to risk-stratify patients for specific ET interventions.

Endovascular versus medical therapy for large-vessel anterior occlusive stroke presenting with mild symptoms.

BACKGROUND: Acute ischemic stroke patients with a large-vessel occlusion but mild symptoms (NIHSS ≤ 6) pose a treatment dilemma between medical management and endovascular thrombectomy. AIMS: To evaluate the differences in clinical outcomes of endovascular thrombectomy-eligible patients with target-mismatch perfusion profiles who undergo either medical management or endovascular thrombectomy. METHODS: Forty-seven patients with acute ischemic stroke due to large-vessel occlusion, NIHSS ≤ 6, and a target-mismatch perfusion imaging profile were included. Patients underwent medical management or endovascular thrombectomy following treating neurointerventionalist and neurologist consensus. The primary outcome measure was NIHSS shift. Secondary outcome measures were symptomatic intracranial hemorrhage, in-hospital mortality, and 90-day mRS scores. The primary intention-to-treat and as-treated analyses were compared to determine the impact of crossover patient allocation on study outcome measures. RESULTS: Forty-seven patients were included. Thirty underwent medical management (64%) and 17 underwent endovascular thrombectomy (36%). Three medical management patients underwent endovascular thrombectomy due to early clinical deterioration. Presentation NIHSS (P = 0.82), NIHSS shift (P = 0.62), and 90-day functional independence (mRS 0-2; P = 0.25) were similar between groups. Endovascular thrombectomy patients demonstrated an increased overall rate of intracranial hemorrhage (35.3% vs. 10.0%; P = 0.04), but symptomatic intracranial hemorrhage was similar between groups (P = 0.25). In-hospital mortality was similar between groups (P = 0.46), though all two deaths in the medical management group occurred among crossover patients. Endovascular thrombectomy patients demonstrated a longer length of stay (7.6 ± 7.2 vs. 4.3 ± 3.9 days; P = 0.04) and a higher frequency of unfavorable discharge to a skilled-nursing facility (P = 0.03) rather than home (P = 0.05). CONCLUSIONS: Endovascular thrombectomy may pose an unfavorable risk-benefit profile over medical management for endovascular thrombectomy-eligible acute ischemic stroke patients with mild symptoms, which warrants a randomized trial in this subpopulation.

Dual-Energy Computed Tomography Applications in Neurointervention.

Dual-energy computed tomography (CT) combines the high spatial resolution of standard CT with the ability to improve contrast resolution, reduce artifact, and separate materials of different atomic weights and energy-based attenuation through postprocessing. We review the underlying physical principles and applications of dual-energy CT within the context of patients undergoing preprocedural and postprocedural evaluation for neurointerventional therapies. The broad imaging categories of cerebral ischemia and hemorrhage, head and neck angiography, and the spine are reviewed.

Can diffusion- and perfusion-weighted imaging alone accurately triage anterior circulation acute ischemic stroke patients to endovascular therapy?

BACKGROUND AND PURPOSE: Acute ischemic stroke (AIS) patients who benefit from endovascular treatment have a large vessel occlusion (LVO), small core infarction, and salvageable brain. We determined if diffusion-weighted imaging (DWI) and perfusion-weighted imaging (PWI) alone can correctly identify and localize anterior circulation LVO and accurately triage patients to endovascular thrombectomy (ET). MATERIALS AND METHODS: This retrospective cohort study included patients undergoing MRI for the evaluation of AIS symptoms. DWI and PWI images alone were anonymized and scored for cerebral infarction, LVO presence and LVO location, DWI-PWI mismatch, and ET candidacy. Readers were blinded to clinical data. The primary outcome measure was accurate ET triage. Secondary outcomes were detection of LVO and LVO location. RESULTS: Two hundred and nineteen patients were included. Seventy-three patients (33%) underwent endovascular AIS treatment. Readers correctly and concordantly triaged 70 of 73 patients (96%) to ET (κ=0.938; P=0.855) and correctly excluded 143 of 146 patients (98%; P=0.942). DWI and PWI alone had a 95.9% sensitivity and a 98.4% specificity for accurate endovascular triage. LVO were accurately localized to the ICA/M1 segment in 65 of 68 patients (96%; κ=0.922; P=0.817) and the M2 segment in 18 of 20 patients (90%; κ=0.830; P=0.529). CONCLUSION: AIS patients with anterior circulation LVO are accurately identified using DWI and PWI alone, and LVO location may be correctly inferred from PWI. MRA omission may be considered to expedite AIS triage in hyperacute scenarios or may confidently supplant non-diagnostic or artifact-limited MRA.