Risks of Undersizing Stent Retriever Length Relative to Thrombus Length in Patients with Acute Ischemic Stroke.

BACKGROUND AND PURPOSE: Results regarding the association of thrombus length, stent retriever length, and recanalization success in patients with acute ischemic stroke are inconsistent. We hypothesized that the ratio of thrombus length to stent retriever length may be of particular relevance. MATERIALS AND METHODS: Patients with acute ischemic stroke undergoing stent retriever thrombectomy at our institution between January 2010 and December 2018 were reviewed retrospectively. Thrombus length was assessed by measuring the susceptibility vessel sign on SWI using a 1.5T or 3T MR imaging scanner. Multivariable logistic regression models were used to determine the association between thrombus length, stent retriever length, and thrombus length/stent retriever length ratio with first-pass recanalization, overall recanalization, and embolization in new territories. Results are shown as adjusted ORs with 95% CIs. Additional mediation analyses were performed to test for indirect effects on first-pass recanalization and overall recanalization success. RESULTS: The main analysis included 418 patients (mean age, 74.9 years). Increasing stent retriever length was associated with first-pass recanalization. Decreasing thrombus length and lower thrombus length/stent retriever length ratios were associated with first-pass recanalization and overall recanalization. Thrombus length and stent retriever length showed no association with first-pass recanalization or overall recanalization once thrombus length/stent retriever length ratio was factored in, while thrombus length/stent retriever length ratio remained a significant factor in both models (adjusted OR, 0.316 [95% CI, 0.112-0.892]; P = .030 and adjusted OR, = 0.366 [95% CI, 0.194-0.689]; P = .002). Mediation analyses showed that decreasing thrombus length and increasing stent retriever length had a significant indirect effect on first-pass recanalization mediated through thrombus length/stent retriever length ratio. The only parameter associated with embolization in new territories was an increasing thrombus length/stent retriever length ratio (adjusted OR, 5.079 [95% CI, 1.332-19.362]; P = .017). CONCLUSIONS: Information about thrombus and stent length is more valuable when combined. High thrombus length/stent retriever length ratios, which may raise the risk of unsuccessful recanalization and embolization in new territories, should be avoided by adapting stent retriever selection to thrombus length whenever possible.

SWI Susceptibility Vessel Sign in Patients Undergoing Mechanical Thrombectomy for Acute Ischemic Stroke.

BACKGROUND AND PURPOSE: The frequency and clinical significance of the susceptibility vessel sign in patients with acute ischemic stroke remains unclear. We aimed to assess its prevalence in patients with acute ischemic stroke undergoing mechanical thrombectomy and to analyze its association with interventional and clinical outcome parameters in that group. MATERIALS AND METHODS: Six hundred seventy-six patients with acute ischemic stroke and admission MR imaging were reviewed retrospectively. Of those, 577 met the eligibility criteria for further analysis. Imaging was performed using a 1.5T or 3T MR imaging scanner. Associations between baseline variables, interventional and clinical outcome parameters, and susceptibility vessel sign were determined with multivariable logistic regression models. Results are shown as adjusted ORs with 95% CIs. RESULTS: The susceptibility vessel sign was present in 87.5% (n = 505) of patients and associated with tandem occlusion (adjusted OR, 3.3; 95% CI, 1.1-10.0; P = .032) as well as successful reperfusion, defined as an expanded TICI score of ≥2b (adjusted OR, 2.4; 95% CI, 1.28-4.6; P = .007). The susceptibility vessel sign was independently associated with functional independence (mRS ≤ 2: adjusted OR, 2.1; 95% CI, 1.1-4.0; P = .028) and lower mortality (adjusted OR, 0.4; 95% CI, 0.2-0.7; P = .003) at 90 days, even after adjusting for successful reperfusion. The susceptibility vessel sign did not influence the number of passes performed during mechanical thrombectomy, the first-pass reperfusion, or the risk of peri- or postinterventional complications. CONCLUSIONS: The susceptibility vessel sign is an MR imaging phenomenon frequently observed in patients with acute ischemic stroke and is associated with successful reperfusion after mechanical thrombectomy. However, superior clinical functional outcome and lower mortality noted in patients showing the susceptibility vessel sign could not be entirely attributed to higher reperfusion rates.

Evolution of MRI Findings in Patients with Idiopathic Intracranial Hypertension after Venous Sinus Stenting.

BACKGROUND AND PURPOSE: The correlation between imaging findings and clinical status in patients with idiopathic intracranial hypertension is unclear. We aimed to examine the evolution of idiopathic intracranial hypertension-related MR imaging findings in patients treated with venous sinus stent placement. MATERIALS AND METHODS: Thirteen patients with idiopathic intracranial hypertension (median age, 26.9 years) were assessed for changes in the CSF opening pressure, transstenotic pressure gradient, and symptoms after venous sinus stent placement. Optic nerve sheath diameter, posterior globe flattening and/or optic nerve protrusion, empty sella, the Meckel cave, tonsillar ectopia, the ventricles, the occipital emissary vein, and subcutaneous fat were evaluated on MR imaging before and 6 months after venous sinus stent placement. Data are expressed as percentages, medians, or correlation coefficients (r) with P values. RESULTS: Although all patients showed significant reductions of the CSF opening pressure (31 versus 21 cm H2O; P = .005) and transstenotic pressure gradient (22.5 versus 1.5 mm Hg; P = .002) and substantial improvement of clinical symptoms 6 months after venous sinus stent placement, a concomitant reduction was observed only for posterior globe involvement (61.5% versus 15.4%; P = .001), optic nerve sheath diameter (6.8 versus 6.1 mm; P < .001), and subcutaneous neck fat (8.9 versus 7.4 mm; P = .001). Strong correlations were observed between decreasing optic nerve sheath diameters and improving nausea/emesis (right optic nerve sheath diameter, r = 0.592, P = .033; left optic nerve sheath diameter, r = 0.718, P = .006), improvement of posterior globe involvement and decreasing papilledema (r = 0.775, P = .003), and decreasing occipital emissary vein diameter and decreasing headache frequency (r = 0.74, P = .035). Decreasing transstenotic pressure gradient at 6 months strongly correlated with decreasing empty sella (r = 0.625, P = .022) and regressing cerebellar ectopia (r = 0.662, P = .019). CONCLUSIONS: Most imaging findings persist long after normalization of intracranial pressure and clinical improvement. However, MR imaging findings related to the optic nerve may reflect treatment success.