MR characteristics of unruptured intracranial arteriovenous malformations associated with seizure as initial clinical presentation.

BACKGROUND: Patients with intracranial arteriovenous malformations (AVMs) are at increased risk of seizures. OBJECTIVE: To identify MRI characteristics of unruptured intracranial AVMs associated with seizures at presentation. MATERIALS AND METHODS: A retrospective review was completed of patients diagnosed with unruptured intracranial AVMs on MRI between January 1, 2000 and December 31, 2016. Two blinded reviewers assessed demographics, lesion locality, and imaging and architectural characteristics of AVMs and surrounding parenchyma, including, but not limited to, AVM location, venous drainage pattern, venous varix, thrombosed venous varix, long draining vein, AVM-related gliosis, peri-AVM edema, and peri-AVM T2* signal. Findings were statistically analyzed for correlation with seizure using Student's t-test for continuous variables and Χ2 test for categorical variables. RESULTS: Of 165 included patients, 57/165 (34.5%) patients were imaged as part of an investigation for seizures. Patients with seizures more commonly had peri-AVM edema (36.8%, compared with 11.1% of non-seizure patients, p<0.0001), peri-AVM T2* blooming (28.1% vs 7.4%; p=0.029), a venous pouch/varix (61.4% vs 31.5%, p=0.0003), long draining vein (91.2% vs 55.6%, p<0.0001), and larger size based on Spetzler-Martin grade categorization (p=0.006). By location, AVMs located in the frontal lobe, primary motor cortex, and primary sensory cortex were associated with seizures (p=0.004, p=0.001, and p=0.006, respectively); temporal lobe location was not associated with seizures (p=0.459). CONCLUSIONS: Certain MRI characteristics of unruptured intracranial AVMs are associated with seizures. Such correlations may assist in identifying the pathophysiological mechanisms by which AVMs cause seizures.

Clot permeability and histopathology: is a clot's perviousness on CT imaging correlated with its histologic composition?

BACKGROUND: Clot perviousness in large vessel occlusion has been shown to be associated with improved recanalization outcomes with mechanical thrombectomy and intravenous thrombolysis. OBJECTIVE: To evaluate the association between clot perviousness based on thrombus attenuation increase (TAI) on CT, and histologic composition of clots in acute ischemic stroke (AIS). METHODS: A retrospective review was completed of patients with AIS secondary to large vessel occlusion, non-contrast CT (NCCT) and CT angiography (CTA) images, and histologic analysis of the retrieved clot. TAI was measured by subtracting clot attenuation on NCCT from the attenuation on CTA. Up to 3 regions of interest (ROIs) were evaluated on each clot; the average attenuation was used for analysis if multiple ROIs were assessed. Pervious clots were defined as TAI ≥10 Hounsfield units (HUs); impervious clots had TAI <10 HU. Histopathologic analyses of clots were assessed for relative compositions of red blood cells (RBCs), white blood cells (WBCs), fibrin, and platelets/other. RESULTS: 57 patients were included. Pervious clots were more likely to be RBC rich (p=0.04); impervious clots were more likely to be fibrin and WBC rich (p=0.01 for both). Pervious clots also had greater RBC density than impervious clots (49.8% and 33.0%, respectively; p=0.006); fibrin density of pervious clots was lower than that of impervious clots (17.8% and 23.2%, respectively; p=0.02). CONCLUSION: Clot perviousness, assessed on NCCT and CTA imaging, is associated with higher RBC density and lower fibrin density, offering a possible explanation for the higher rates of successful thrombectomy and favorable clinical outcome seen in such patients.

Per-region interobserver agreement of Alberta Stroke Program Early CT Scores (ASPECTS).

BACKGROUND AND PURPOSE: The Alberta Stroke Program Early CT Score (ASPECTS) is a commonly used scoring system to select patients with stroke for endovascular treatment (EVT). However, the inter- and intra-reader variability is high. OBJECTIVE: To determine whether the inter- and intra-reader variability is different for various regions of the ASPECTS scoring system by evaluating the interobserver variability of ASPECTS between different readers in a per-region analysis. MATERIALS AND METHODS: All patients with acute ischemic stroke who proceeded to EVT in our institutions over a 4-year period were retrospectively identified from a prospectively maintained database. Images were reviewed by two experienced neuroradiologists, who recalculated the ASPECTS independently. We examined each region of the ASPECTS system to evaluate agreement between the raters in each area. RESULTS: 375 patients were included. The median total ASPECTS was 9 (IQR 8-9). The most common region showing ischemic change was the insula, with the M6 region being least commonly affected. Overall interobserver agreement for ASPECTS using Cohen's κ was 0.56 (95% CI 0.51 to 0.61). The region with the highest agreement was the insula (κ=0.56; 0.48 to 0.64). The region with the lowest agreement was M3 (κ=0.34; 0.12 to 0.56). Agreement was relatively good when ASPECTS were dichotomized into 0-5 versus 6-10 (κ=0.66; 0.49 to 0.84). CONCLUSIONS: Substantial interobserver variability is found when calculating ASPECTS. This variability is region dependent, and practitioners should take this into account when using ASPECTS for treatment decisions in patients with acute stroke.