Reliability of Two Diameters Method in Determining Acute Infarct Size. Validation as New Imaging Biomarker

The impact of asymptomatic intracranial atherosclerotic stenosis on the clinical outcomes of patients with single subcortical infarction

Background

The presence of parental arterial disease (PAD) is correlated with the outcomes of patients with a single subcortical infarction (SSI). Due to the relatively low incidence of PAD, the predictors of outcomes seem to be limited for SSI patients without PAD. This study aims to investigate the association between asymptomatic intracranial atherosclerotic stenosis (aIAS) and outcomes in patients with SSI and in the subgroup without PAD.

Methods

Patients with SSI were consecutively enrolled. aIAS referred to a stenosis of ≥50% in intracranial arteries irrelevant to SSI by using magnetic resonance angiography. A poor outcome refers to a modified Ranking Scale >2 points at discharge.

Results

In total, 298 participants were enrolled. The presence of aIAS could predict a poor outcome for all SSI patients [adjusted relative risk (aRR) = 2.14, 95% confidence interval (CI) = 1.17-3.93, p = 0.014] and in the subgroup without PAD (aRR = 3.12, 95% CI = 1.47-6.62, p = 0.003), but not in the subgroup with PAD. Compared with participants with neither aIAS nor PAD, the risk of a poor outcome increased approximately 2-fold in those with aIAS only (aRR = 2.95, 95% CI = 1.55-5.60, p = 0.001) and in those with concomitant aIAS and PAD (aRR = 3.10, 95% CI = 1.62-5.95, p = 0.001).

Conclusion

The presence of aIAS is a predictor of a poor outcome in SSI patients, especially in those without PAD.

Poststroke neutrophil count is predictive of the outcomes of large-artery atherosclerotic stroke and associated with craniocervical atherosclerosis

Elevation of the neutrophil count is detrimental to the outcome of patients with stroke. The effect of poststroke neutrophil count on the outcome of patients with large-artery atherosclerosis (LAA) stroke is unclear. This study aims to explore the relationship of poststroke neutrophil count with the functional outcome of patients with LAA stroke, and the relationship of poststroke neutrophil count and craniocervical atherosclerotic stenosis (AS) number in these patients. The AS was defined as ≥ 50% stenosis or occlusion attributed to atherosclerosis on craniocervical large arteries. A total of 297 participants were enrolled in the cohort. In multivariable analyses, neutrophil count [adjusted relative risk (aRR) = 1.23, 95% confidence interval (CI) 1.09-1.40, p = 0.001] was an independent predictor of 90-day poor functional outcome [modified Rankin Scale (mRS) > 2 points]. The neutrophil count was significantly associated with the craniocervical AS number in a multivariable ordinal logistic regression analysis [adjusted odds ratio (aOR) = 1.41, 95% CI 1.16-1.72, p = 0.001]. The poststroke neutrophil count is a valuable predictor of 90-day poor functional outcome of patients with LAA stroke. The poststroke neutrophil count is positively correlated with the craniocervical AS number in these patients.

Use of ABC/2 method for rapidly estimating the target mismatch on computed tomography perfusion imaging in patients with acute ischemic stroke

BACKGROUND

Target mismatch (ischemic core, mismatch volume and mismatch ratio) in patients with acute ischemic stroke (AIS) highly relies on the automated perfusion analysis software.

PURPOSE

To evaluate the feasibility and accuracy of using the ABC/2 method to rapidly estimate the target mismatch on computed tomography perfusion (CTP) imaging in patients with AIS, using RAPID results as a reference.

MATERIAL AND METHODS

In total, 243 patients with anterior circulation AIS who underwent CTP imaging were retrospectively reviewed. Target mismatch associated perfusion parameters were derived from RAPID results and calculated using the ABC/2 method. Paired t-test was used to assess the difference of volumetric parameters between the two methods. The ability of using the ABC/2 method to predict the important cutoff volumetric metrics was also evaluated.

RESULT

There was no significant difference in the volumes of ischemic core (P = 0.068), ischemic area (P = 0.209), and mismatch volume (P = 0.518) between ABC/2 and RAPID. Using RAPID results as reference, the ABC/2 method showed high accuracy for predicting perfusion parameters (70 mL and 90 mL: sensitivity=98.5% and 98.5%, specificity=100% and 100%, positive predictive value [PPV]=100% and 100%, negative predictive value [NPV]=93.8% and 92.9%; 10 mL and 15mL: sensitivity=99.6% and 99.5%, specificity=55.6% and 50.0%, PPV=96.6% and 94.8%, NPV=90.9% and 92.3%; 1.2 and 1.8: sensitivity=99.6% and 94.8%, specificity=75.0% and 96.9%, PPV=98.7% and 99.5%, NPV=90.0% and 73.8%).

CONCLUSION

The ABC/2 method may be a feasible alternative to RAPID for estimation of target mismatch parameters on CTP in patients with AIS.

Barrel cortex plasticity after photothrombotic stroke involves potentiating responses of pre-existing circuits but not functional remapping to new circuits

Recovery after stroke is thought to be mediated by adaptive circuit plasticity, whereby surviving neurons assume the roles of those that died. However, definitive longitudinal evidence of neurons changing their response selectivity after stroke is lacking. We sought to directly test whether such functional “remapping” occurs within mouse primary somatosensory cortex after a stroke that destroys the C1 barrel. Using in vivo calcium imaging to longitudinally record sensory-evoked activity under light anesthesia, we did not find any increase in the number of C1 whisker-responsive neurons in the adjacent, spared D3 barrel after stroke. To promote plasticity after stroke, we also plucked all whiskers except C1 (forced use therapy). This led to an increase in the reliability of sensory-evoked responses in C1 whisker-responsive neurons but did not increase the number of C1 whisker-responsive neurons in spared surround barrels over baseline levels. Our results argue against remapping of functionality after barrel cortex stroke, but support a circuit-based mechanism for how rehabilitation may improve recovery.

Definitive evidence for functional remapping after stroke remains lacking. Here, the authors performed in vivo intrinsic signal imaging and two-photon calcium imaging of sensory-evoked responses before and after photothrombotic stroke and found no evidence of remapping of lost functionalities to new circuits in peri-infarct cortex.

Temporal and Spatial Dynamics of Inflammasome Activation After Ischemic Stroke

Background: The inflammasome represents a highly pro-inflammatory mechanism. It has been identified that inflammasome was activated after ischemic stroke. However, the impact of inflammasomes on stroke outcomes remains contradictory. The participating molecules and the functioning arena of post-stroke inflammasome activation are still elusive.

Methods: In the present study, blood samples from stroke patients were collected and analyzed with flow cytometry to evaluate the correlation of inflammasome activation and stroke outcomes. A stroke model was established using male C57/Bl6 mice with transient middle cerebral artery occlusion (tMCAO, 1 h). The dynamics of inflammasome components, cell type, and location of inflammasome activation and the therapeutic effects of inhibiting post-stroke inflammasome executors were evaluated.

Results: We found that a high level of inflammasome activation might indicate detrimental stroke outcomes in patients and mice models. Post-stroke inflammasome activation, especially NLRP3, cleaved Caspase-1, cleaved Caspase-11, IL-1β, IL-18, and GSDMD, peaked at 3–5 days and declined at 7 days with the participation of multiple components in mice. Macrophage that infiltrated into the ischemic lesion was the main arena for post-stroke inflammasome activation among myeloid cells according to the data of mice. Among all the members of the Caspase family, Caspase-1 and −11 served as the main executing enzymes. Inhibiting Caspase-1/−11 signaling efficiently suppressed DAMPs-induced macrophage inflammasome activation and displayed neuroprotection to stroke models including infarct size (Control: 48.05 ± 14.98; Cas1.i: 19.34 ± 12.21; Cas11.i: 21.43 ± 14.67, P < 0.001) and neurological deficit score (0 d-Control: 2.20 ± 0.63; 0 d-Cas1.i: 2.20 ± 0.63; 0 d-Cas11.i: 2.20 ± 0.63; 1 d-Control: 2.50 ± 0.53; 1 d-Cas1.i: 1.50 ± 0.71; 1 d-Cas11.i: 2.00 ± 0.67; 2 d-Control: 2.30 ± 0.48; 2 d-Cas1.i: 1.30 ± 0.48; 2 d-Cas11.i: 1.50 ± 0.53; 3 d-Control: 2.00 ± 0.67; 3 d-Cas1.i: 1.20 ± 0.42; 3 d-Cas11.i: 1.30 ± 0.48, P < 0.001).

Conclusions: Taken together, inflammasome activation played a detrimental role in stroke pathology. Targeting post-stroke inflammasome executing enzymes fitting in the dynamics of macrophages might obtain potential and efficient therapeutic effects.

Reliability and Reproducibility of the Diameters Method in Rapid Determination of Acute Infarct Volume in Magnetic Resonance Diffusion-Weighted Imaging

<b><i>Background:</i></b> In acute ischemic stroke, diffusion-weighted imaging (DWI) volume is an independent predictive factor of poor outcome and an exclusion criterion for thrombolytic treatment. A simplified diameters method (ABC/2, orthogonal diameter [OD], and the maximum diameter [MD]) was proposed to replace the conventional measuring method and overcome the tedious and time-consuming defects, but its accuracy remains to be determined. <b><i>Objective:</i></b> The objective of this study is to clarify the reliability and reproducibility of the diameter-based estimations in the infarct volume in DWI (Vol-DWI) measured by automated software. <b><i>Methods:</i></b> Data of 316 patients with acute ischemic stroke who underwent MRI within 72 h at Jinling Hospital were retrospectively reviewed. Subgroup analysis by the location (cortex, white matter and deep gray nuclei, and combined) and volume (&#x3c;70 and &#x3e;70 mL) of cerebral infarction was evaluated. Relationship and consistency between the diameters methods and Vol-DWI were determined using Spearman rank correlation, Wilcoxon signed-rank test, and Bland-Altman plots. The OD and MD thresholds indicating infarct size &#x3e;15, 70, and 100 mL were determined by generating receiver-operating characteristic (ROC) curves. Interobserver reliability was established using intraclass correlation coefficient and Bland-Altman plot. <b><i>Results:</i></b> There was a strong positive correlation between the diameters and the Vol-DWI (ABC/2: <i>r</i> = 0.992, OD: <i>r</i> = 0.984, MD: <i>r</i> = 0.970, <i>p</i> &#x3c; 0.001). Infarct volumes measured using the ABC/2 formula were significantly lower than those measured with Vol-DWI (Wilcoxon signed-rank test, <i>z</i> = 6.476, <i>p</i> &#x3c; 0.001). Bland-Altman plot showed that the agreement of the volume &#x3c;70 mL group, and white matter and deep gray nuclei groups was better than that of the other subgroups. For infarct volumes &#x3e;15, 70, and 100 mL, the cutoff value for the MD was identified at 5, 6.9, and 8.4 cm, and the OD was identified at 12.47, 26.4, and 36.4 cm², respectively, with a sensitivity and specificity &#x3e;90%. <b><i>Conclusions:</i></b> The MD method was the best for achieving a rapid and excellent interobserver reliability for estimating infarct volume. Both OD and MD methods can quickly screen patients suitable for recanalization treatment and predict poor prognosis through threshold evaluation.

Two simple and rapid methods based on maximum diameter accurately estimate large lesion volumes in acute stroke

BACKGROUND

We compared two simple and rapid diameter-based methods (ABC/2, od-value) in terms of their accuracy in predicting lesion volume >70 ml and >100 ml.

METHODS

In 238 DWI images of ischemic stroke patients from the AXIS2 trial, maximum lesion diameter and corresponding maximum orthogonal diameter were measured. Estimation of infarct volume based on od-value and ABC/2 calculation was compared to volumetric assessments.

RESULTS

Accuracy of od-value and ABC/2 was similar for >70 ml (92.0 vs. 87.4) and >100 ml (92.9 vs. 93.3). ABC/2 overestimated lesion volume by 29.9%, resulting in a lower specificity.

CONCLUSIONS

Od-value is a robust tool for patient selection in trials.

Maximum lesions area and orthogonal values accessed from DWI images would be alternative imaging markers for predicting the outcome of acute ischemia in the middle cerebral artery territory

BACKGROUND

Evaluating the acute ischemic volume on diffusion-weighted imaging (DWI) in the middle cerebral artery (MCA) territory would predict outcome.

PURPOSE

To investigate the correlations between maximum area with restricted diffusion (MaxA), the orthogonal diameters (OD) as well as lesion volume on DWI, and to explore the role of MaxA and OD on predicting unfavorable outcome after an acute MCA ischemic stroke.

MATERIAL AND METHODS

Sixty consecutive adult patients, including modified Rankin Scale score (mRS) ≤2 (n = 31) and mRS > 2 (n = 29) groups, were retrospectively enrolled. The MaxA and OD of lesions were assessed at the slice containing the largest infarction size on DWI images. We compared the prediction efficiencies of these methods on unfavorable outcomes.

RESULTS

The correlation coefficients between the MaxA and infarction volume and OD and infarction volume were 0.982 ( P < 0.001) and 0.952 ( P < 0.001), respectively. The times required for measuring MaxA (150 s [130-160]) and OD (30 s [20-60]) were much shorter than that for infarction volume measurement (1240 s [180-1480]) ( P = 0.001, P = 0.004). With thresholds of ≥57.3 mL for infarction volume, ≥15.2 cm² for MaxA, and ≥38.1 for the arithmetic product of OD, the AUCs of infarction volume, MaxA, and OD for predicting an unfavorable outcome were 0.818, 0.821, and 0.820, respectively.

CONCLUSION

Since they correlated well with the infarction volume, MaxA and OD assessed on DWI were time-saving and achieved comparable diagnostic efficiencies; thus, they may represent alternative imaging markers for predicting unfavorable outcomes of acute ischemic stroke in MCA territory.

Functional Dynamics of Neutrophils After Ischemic Stroke

Neutrophils are forerunners to brain lesions after ischemic stroke and exert elaborate functions. However, temporal alterations of cell count, polarity, extracellular trap formation, and clearance of neutrophils remain poorly understood. The current study was aimed at providing basic information of neutrophil function throughout a time course following stroke onset in patients and animal subjects. We found that neutrophil constitution in peripheral blood increased soon after stroke onset of patients, and higher neutrophil count indicated detrimental stroke outcomes. Comparably, neutrophil count in peripheral blood of stroke mice peaked at 12 h after cerebral ischemia, followed by a 1-2-day spike in brain lesions. In stroke lesion, clearance of neutrophils peaked at 2 days after stroke and extracellular traps were mostly detected at 2-3 days after stroke. In neutrophil infiltrated into stroke lesion, expression of the N2 marker CD206 was relatively stable. We found that the N2 phenotype facilitated neutrophil clearance by macrophage and did not further induce neuronal death after ischemic injury compared with N0 or N1 neutrophils. Skewing neutrophil toward the N2 phenotype before stroke reduced infarct volumes at 1 day after tMCAO. Conditioned medium of ischemic neurons drove neutrophils away from the protective N2 phenotype and increased the formation of extracellular traps. Conclusively, neutrophil function has an important impact on stroke outcomes. Neutrophil frequency in the peripheral blood could be an early indicator of stroke outcomes. N2 neutrophils facilitate macrophage phagocytosis and are less harmful to ischemic neurons. Directing neutrophils toward the N2 phenotype could be a promising therapeutic approach for ischemic stroke.