Prominent hypointense vessel on susceptibility-weighted images accompanying hyperacute and acute large infarction

A Minimalist Iron Oxide Nanoprobe for the High-Resolution Depiction of Stroke by Susceptibility-Weighted Imaging

The precise mapping of collateral circulation and ischemic penumbra is crucial for diagnosing and treating acute ischemic stroke (AIS). Unfortunately, there exists a significant shortage of high-sensitivity and high-resolution in vivo imaging techniques to fulfill this requirement. Herein, a contrast enhanced susceptibility-weighted imaging (CE-SWI) using the minimalist dextran-modified Fe3O4 nanoparticles (Fe3O4@Dextran NPs) are introduced for the highly sensitive and high-resolution AIS depiction under 9.4 T for the first time. The Fe3O4@Dextran NPs are synthesized via a simple one-pot coprecipitation method using commercial reagents under room temperature. It shows merits of small size (hydrodynamic size 25.8 nm), good solubility, high transverse relaxivity (r2) of 51.3 mM-1s-1 at 9.4 T, and superior biocompatibility. The Fe3O4@Dextran NPs-enhanced SWI can highlight the cerebral vessels readily with significantly improved contrast and ultrahigh resolution of 0.1 mm under 9.4 T MR scanner, enabling the clear spatial identification of collateral circulation in the middle cerebral artery occlusion (MCAO) rat model. Furthermore, Fe3O4@Dextran NPs-enhanced SWI facilitates the precise depiction of ischemia core, collaterals, and ischemic penumbra post AIS through matching analysis with other multimodal MR sequences. The proposed Fe3O4@Dextran NPs-enhanced SWI offers a high-sensitivity and high-resolution imaging tool for individualized characterization and personally precise theranostics of stroke patients.

Prominent Vessel Signs After Endovascular Thrombectomy Corelates with Unexplained Neurological Deterioration and is a More Reliable Imaging Predictor of Prognosis in Anterior Large Vessel Occlusion Stroke

OBJECTIVE

Fifty percent of patients who undergo endovascular thrombectomy (EVT) for large-vessel occlusion exhibit unfavorable outcomes. The primary factor is attributed to persistent brain impairment even after successful EVT. The prominent vessel sign (PVS) on magnetic resonance susceptibility-weighted imaging reflects the territory of dysmetabolism and may facilitate an expeditious assessment for prognostication. We aimed to examine the relationship between PVS after EVT and the occurrence of early neurological deterioration (END) and 3-month outcomes.

METHODS

Patients who underwent EVT and multimodal magnetic resonance imaging were included. END was defined as an increase of ≥2 in the National Institutes of Health Stroke Scale within 72 hours after EVT. Symptomatic intracranial hemorrhage, malignant edema, and surgical complications were defined as definite END, whereas the other symptoms were categorized as unexplained END (ux-END). The PVS-Alberta Stroke Program Early CT Score (ASPECTS) score was used to evaluate the asymmetric cerebral venous signal on the susceptibility-weighted imaging sequences semiquantitatively.

RESULTS

A total of 116 eligible patients were included, 18 (15.5%) of whom presented with ux-END. The 72 hour National Institutes of Health Stroke Scale was strongly correlated with diffusion-weighted imaging infarct volume and PVS-ASPECTS and was significantly higher in the ux-END group (16 ± 6 vs. 5 ± 4, P = 0.001). The PVS-ASPECTS score was significantly associated with poor outcomes (odds ratio 2.551, 95% confidence interval (CI) 1.722-3.780, P＜0.001), and PVS-ASPECTS (area under the curve 0.884, 95% CI 0.815-0.953, P < 0.001) was superior to diffusion-weighted imaging infarct volume (area under the cure 0.720, 95% CI 0.620-0.820, P = 0.001) in predicting 3-month poor outcome. At the optimal cut-off of 2, the PVS-ASPECT predicted poor outcomes with a sensitivity of 89.7% and a specificity of 78.2%.

CONCLUSIONS

PVS 72 hours after EVT correlated with ux-END. The PVS-ASPECTS is a more reliable predictor of stroke prognosis and provides valuable information regarding post-EVT management.

Vessel wall MR imaging in neuroradiology

Vessel wall MR imaging (VW-MRI) has been introduced into clinical practice and applied to a variety of diseases, and its usefulness has been reported. High-resolution VW-MRI is essential in the diagnostic workup and provides more information than other routine MR imaging protocols. VW-MRI is useful in assessing lesion location, morphology, and severity. Additional information, such as vessel wall enhancement, which is useful in the differential diagnosis of atherosclerotic disease and vasculitis could be assessed by this special imaging technique. This review describes the VW-MRI technique and its clinical applications in arterial disease, venous disease, vasculitis, and leptomeningeal disease.

Diffusion- and Susceptibility Weighted Imaging Mismatch Correlates With Collateral Circulation and Prognosis After Middle Cerebral Artery M1-Segment Occlusion

Objective: To explore the relation between diffusion-weighted and susceptibility weighted imaging (DWI-SWI) mismatch and collateral circulation or prognosis in patients with occluded M1 segments of middle cerebral artery (MCA).

Methods: We enrolled 59 patients with MCA M1-segment occlusion for a retrospective review of baseline clinical and imaging data. As markers of circulatory collaterals, prominent laterality of posterior (PLPCA) and anterior (PLACA) cerebral arteries on magnetic resonance angiography (MRA) studies and a hyperintense vessel sign (HVS) on T2 fluid-attenuated inversion recovery (FLAIR) images were collectively scored. The extent of acute cerebral infarction was then quantified on DWI, using the Alberta Stroke Program Early CT Score (DWI-ASPECTS). Hypointensity vessel sign prominence (PVS) was also evaluated by SWI and similarly scored (SWI-ASPECT) to calculate DWI-SWI mismatch [(DWI-ASPECTS) – (SWI-ASPECTS)], ranging from −10 to 10 points.

Results: DWI-SWI mismatch showed significant associations with PLPCA, PLACA, HVS prominence, and collective collateral scores (all, p < 0.05). National Institutes of Health Stroke Scale (NIHSS), DWI-SWI mismatch, and DWI-ASPECTS also differed significantly according to patient prognosis (good vs. poor) after MCA M1-segment occlusion (p < 0.05). In binary logistic regression analyses, NIHSS and DWI-SWI mismatch emerged as independent prognostic factors (p < 0.05).

Conclusions: Collateral circulation may be an important aspect of DWI-SWI mismatch, which in this study correlated with prognostic outcomes of MCA M1-segment occlusion.