Neuromyelitis optica (NMO) is an autoimmune demyelinating disorder for which the aquaporin-4 (AQP4) water channels are the major target antigens. Advances in the understanding of NMO have clarified several points of its pathogenesis, clinical manifestations, and imaging patterns. A major advance was the discovery of the AQP4 antibody, which is highly specific for this disorder. Descriptions of new clinical and radiologic features in seropositive patients have expanded the spectrum of NMO, and the term NMO spectrum disorder (NMOSD) has been adopted. NMOSD is now included in a widening list of differential diagnoses. Acknowledgment of NMOSD imaging patterns and their mimicry of disorders has been crucial in supporting early NMOSD diagnosis, especially for unusual clinical manifestations of this demyelinating disease. This pictorial review summarizes the wide imaging spectrum of NMOSD and its differential diagnosis, as well as its historical evolution, pathophysiology, and clinical manifestations. RSNA, 2018.

Background and Purpose— Thrombus imaging characteristics have been reported to be useful to predict functional outcome and reperfusion in acute ischemic stroke. However, conflicting data about this subject exist in patients undergoing endovascular treatment. Therefore, we aimed to evaluate whether thrombus imaging characteristics assessed on computed tomography are associated with outcomes in patients with acute ischemic stroke treated by endovascular treatment. Methods— The MR CLEAN (Multicenter Randomized Clinical Trial of Endovascular Treatment for Acute Ischemic Stroke in the Netherlands) Registry is an ongoing, prospective, and observational study in all centers performing endovascular treatment in the Netherlands. We evaluated associations of thrombus imaging characteristics with the functional outcome (modified Rankin Scale at 90 days), mortality, reperfusion, duration of endovascular treatment, and symptomatic intracranial hemorrhage using univariable and multivariable regression models. Thrombus characteristics included location, clot burden score (CBS), length, relative and absolute attenuation, perviousness, and distance from the internal carotid artery terminus to the thrombus. All characteristics were assessed on thin-slice (≤2.5 mm) noncontrast computed tomography and computed tomography angiography, acquired within 30 minutes from each other. Results— In total, 408 patients were analyzed. Thrombus with distal location, higher CBS, and shorter length were associated with better functional outcome (adjusted common odds ratio, 3.3; 95% CI, 2.0–5.3 for distal M1 occlusion compared with internal carotid artery occlusion; adjusted common odds ratio, 1.15; 95% CI, 1.07–1.24 per CBS point; and adjusted common odds ratio, 0.96; 95% CI, 0.94–0.99 per mm, respectively) and reduced duration of endovascular procedure (adjusted coefficient B, −14.7; 95% CI, −24.2 to −5.1 for distal M1 occlusion compared with internal carotid artery occlusion; adjusted coefficient B, −8.5; 95% CI, −14.5 to −2.4 per CBS point; and adjusted coefficient B, 7.3; 95% CI, 2.9–11.8 per mm, respectively). Thrombus perviousness was associated with better functional outcome (adjusted common odds ratio, 1.01; 95% CI, 1.00–1.02 per Hounsfield units increase). Distal thrombi were associated with successful reperfusion (adjusted odds ratio, 2.6; 95% CI, 1.4–4.9 for proximal M1 occlusion compared with internal carotid artery occlusion). Conclusions— Distal location, higher CBS, and shorter length are associated with better functional outcome and faster endovascular procedure. Distal thrombus is strongly associated with successful reperfusion, and a pervious thrombus is associated with better functional outcome.

It is uncertain whether therapeutic reperfusion with endovascular treatment yields more or less brain edema. OBJECTIVE To elucidate the association between reperfusion and brain edema. The secondary objectives were to evaluate whether brain edema could partially be responsible for worse outcomes in patients with later reperfusion or lower Alberta Stroke Program Early Computed Tomography Score. DESIGN, SETTING, AND PARTICIPANTS This was a post hoc analysis of the Multicenter Randomized Clinical Trial of Endovascular Treatment for Acute Ischemic Stroke in the Netherlands (MR CLEAN), which was a prospective, randomized, multicenter clinical trial of endovascular treatment compared with conventional care of patients with acute anterior circulation ischemic stroke. Of 502 patients enrolled from December 2010 to June 2014, 2 patients declined to participate. Additionally, exclusion criteria were absence of follow-up imaging or presence of parenchymal hematoma, resulting in 462 patients included in this study. Brain edema was assessed retrospectively, from December 10, 2016, to July 24, 2017, by measuring midline shift (MLS) in all available follow-up scans. Observers were blinded to clinical data. MAIN OUTCOMES AND MEASURES Midline shift was assessed as present or absent and as a continuous variable. Reperfusion status was assessed by the modified thrombolysis in cerebral infarction score in the endovascular treatment arm. The modified arterial occlusive lesion score was used to evaluate the recanalization status in both arms. The modified Rankin scale score at 90 days was used for functional outcome. RESULTS Of 462 patients, the mean (SD) age was 65 (11) years, and 41.8% (n = 193) were women. Successful reperfusion and recanalization were associated with a reduced likelihood of having MLS (adjusted common odds ratio, 0.25; 95% CI, 0.12-0.53; P < .001 and adjusted common odds ratio, 0.34; 95% CI, 0.21-0.55; P < .001, respectively). Midline shift was partially responsible for worse modified Rankin scale scores in patients without reperfusion or recanalization (MLS changed the logistic regression coefficients by 30.3% and 12.6%, respectively). In patients with delayed reperfusion or lower Alberta Stroke Program Early Computed Tomography Score, MLS mediated part of the worse modified Rankin scale scores, corresponding to a change in the regression coefficient of 33.3% and 64.2%, respectively. CONCLUSIONS AND RELEVANCE Successful reperfusion was associated with reduced MLS. This study identifies an additional benefit of reperfusion in relation to edema, as well as rescuing ischemic brain tissue at risk for infarction.

Background and Purpose— The location of the thrombus as observed on first digital subtraction angiography during endovascular treatment may differ from the initial observation on initial noninvasive imaging. We studied the incidence of thrombus dynamics, its impact on patient outcomes, and its association with intravenous thrombolytics. Methods— We included patients from the MR CLEAN registry (Multicenter Randomized Clinical Trial of Endovascular Treatment of Acute Ischemic Stroke) with an initial target occlusion on computed tomography angiography located in the intracranial internal carotid artery, M1, or M2. The conventional angiography target occlusion was defined during endovascular treatment. Thrombus dynamics were classified as growth, stability, migration, and resolution. The primary outcome was functional outcome at 90 days (modified Rankin Scale). The secondary outcomes were successful and complete reperfusion (extended treatment in cerebral infarction scores of 2b-3 and 3, respectively). Results— The analysis included 1349 patients. Thrombus migration occurred in 302 (22%) patients, thrombus growth in 87 (6%), and thrombus resolution in 39 (3%). Intravenous treatment with alteplase was associated with more thrombus migration (adjusted odds ratio, 2.01; CI, 1.29–3.11) and thrombus resolution (adjusted odds ratio, 1.85; CI, 1.22–2.80). Thrombus migration was associated with a lower chance of complete reperfusion (adjusted odds ratio, 0.57; CI, 0.42–0.78) and successful reperfusion (adjusted odds ratio, 0.74; CI, 0.55–0.99). In the subgroup of patients with M1 initial target occlusion, thrombus migration was associated with better functional outcome (adjusted common odds ratio, 1.49; CI, 1.02–2.17), and there was a trend towards better functional outcome in patients with thrombus resolution (adjusted common odds ratio, 2.23; CI, 0.93–5.37). Conclusions— In patients with acute ischemic stroke, thrombus location regularly changes between computed tomography angiography and digital subtraction angiography. Administration of intravenous alteplase increases the chance of thrombus migration and resolution. Thrombus migration is associated with better functional outcome but reduces the rate of complete reperfusion.

Background and Purpose— If a relationship between stroke etiology and thrombus computed tomography characteristics exists, assessing these characteristics in clinical practice could serve as a useful additional diagnostic tool for the identification of stroke subtype. Our purpose was to study the association of stroke etiology and thrombus computed tomography characteristics in patients with acute ischemic stroke due to a large vessel occlusion. Methods— For 1429 consecutive patients enrolled in the MR CLEAN Registry, we determined stroke cause as defined by the TOAST (Trial of ORG 10172 in Acute Stroke Treatment) criteria. The association of stroke etiology with the hyperdense artery sign, clot burden score, and thrombus location was estimated with univariable and multivariable binary and ordinal logistic regression. Additionally, for 367 patients with available thin-section imaging, we assessed the association of stroke etiology with absolute and relative thrombus attenuation, distance from internal carotid artery-terminus to thrombus, thrombus length, and thrombus attenuation increase with univariable and multivariable linear regression. Results— Compared with cardioembolic strokes, noncardioembolic strokes were associated with presence of hyperdense artery sign (odds ratio, 2.2 [95% CI, 1.6–3.0]), lower clot burden score (common odds ratio, 0.4 [95% CI, 0.3–0.6]), shift towards a more proximal thrombus location (common odds ratio, 0.2 [95% CI, 0.2–0.3]), higher absolute thrombus attenuation (β, 3.6 [95% CI, 0.9–6.4]), decrease in distance from the ICA-terminus (β, −5.7 [95% CI, −8.3 to −3.0]), and longer thrombi (β, 8.6 [95% CI, 6.5−10.7]), based on univariable analysis. Thrombus characteristics of strokes with undetermined cause were similar to those of cardioembolic strokes. Conclusions— Thrombus computed tomography characteristics of cardioembolic stroke are distinct from those of noncardioembolic stroke. Additionally, our study supports the general hypothesis that many cryptogenic strokes have a cardioembolic cause. Further research should focus on the use of thrombus computed tomography characteristics as a diagnostic tool for stroke cause in clinical practice.