Early Detection of Cerebral Infarction After Focal Ischemia Using a New MRI Indicator

Impaired T1 mapping and Tmax during the first 7 days after ischemic stroke. A retrospective observational study

OBJECTIVE

To measure the relative T1 (rT1) value in different hypo-perfused regions after ischemic stroke using T1 mapping derived by Strategically Acquired Gradient Echo (STAGE) and assess its relationship with onset time and severity of ischemia.

MATERIALS AND METHODS

Sixty-three patients with acute anterior circulation ischemic stroke from 2017 to 2022 who underwent STAGE, diffusion weighted imaging (DWI) and dynamic susceptibility contrast perfusion weighted imaging (DSC-PWI) within 7 days were retrospectively enrolled. The areas with reduced diffusion and hypo-perfusion were segmented based on apparent diffusion coefficient (ADC) value < 0.62 × 10-3mm2/s and time-to-maximum (Tmax) thresholds (4, 6, 8, and 10 seconds). We measured the T1 value in the diffusion reduced and every 2 s Tmax strata regions and calculated rT1 (T1ipsi/T1contra) to explore the relationship between rT1 value, Tmax, and onset time.

RESULTS

rT1 value was increased in diffusion reduced (1.42) and hypo-perfused regions (1.02, 1.06, 1.12, 1.27, Tmax 4-6 s, 6-8 s, 8-10 s, > 10 s, respectively; all different from 1, P < 0.001). rT1 value was positively correlated with Tmax (rs = 0.61, P < 0.001) and onset time in area with reduced diffusion (rs = 0.39, P = 0.014).

CONCLUSIONS

Increased rT1 value in different hypo-perfused brain regions using T1 mapping derived by STAGE may reflect the edema; it was associated with the severity of Tmax and showed a weak correlation with the onset time in diffusion reduced areas.

The Key Role of Magnetic Resonance Imaging in the Detection of Neurodegenerative Diseases-Associated Biomarkers: A Review

Neurodegenerative diseases (NDs), including chronic disease such as Alzheimer's disease, Parkinson's disease, Huntington's disease, and multiple sclerosis, and acute diseases like traumatic brain injury and ischemic stroke are characterized by progressive degeneration, brain tissue damage and loss of neurons, accompanied by behavioral and cognitive dysfunctions. So far, there are no complete cures for NDs; thus, early and timely diagnoses are essential and beneficial to patients' treatment. Magnetic resonance imaging (MRI) has become one of the advanced medical imaging techniques widely used in the clinical examination of NDs due to its non-invasive diagnostic value. In this review, research published in English in current decade from PubMed electronic database on the use of MRI to detect specific biomarkers of NDs was collected, summarized, and discussed, which provides valuable suggestions for the early diagnosis, prevention, and treatment of NDs in the clinic.

Observation of the Effect of Nursing BPR on Thrombolytic Efficacy and Prognosis of Patients with Cerebral Infarction Based on CT Images

Cerebral infarction has become the main cause of death among Chinese residents, especially ischemic cerebral infarction. The existing CT technology is not very effective for the detection of cerebral infarction, and some angiography has problems such as blurring and shadowing. In order to understand the treatment methods and effects of patients with cerebral infarction, this article observes the effect of nursing BPR on thrombolytic efficacy and prognosis of patients with cerebral infarction based on CT images. The patients were divided into thrombolytic group and nonthrombolytic group, and a simple rating scale was used to assess the motor function of the patients' limbs, and the stroke scale was used to assess the patient's neurological function. Compare the baseline data, the time of admission, 24 hours and 7 days, the scores before and after treatment, and the ratio between the two groups. According to the monitoring, record each time point. The analysis of the occurrence of primary endpoint was events and secondary endpoint events and risk factors affecting limb motor function. The results of the study found that, based on the computer scanning observation of nursing BPR, compared with the traditional model, the patient's bleeding was significantly reduced, and the time required for nursing was also reduced by more than 50% compared with the traditional model. Compared with the traditional nursing model, the satisfaction of patients with the BPR nursing model is nearly 40% higher than that of the traditional nursing model. This shows that the observation of thrombolytic effect in patients with cerebral infarction based on computed tomography and BPR nursing can produce good therapeutic effects.

The Role of Apparent Diffusion Coefficient Values in Glioblastoma: Differentiating Tumor Progression Versus Treatment-Related Changes

OBJECTIVE

Glioblastoma represents the most common primary brain malignancy with a median survival of 15 months. Follow-up examinations are crucial to establish the presence of tumor recurrence, as well as treatment-associated changes such as ischemic infarction and radiation effects. Even though magnetic resonance imaging is a valuable tool, a histopathological diagnosis is often required because of imaging overlap between tumor recurrence and treatment associated changes. We set out to measure the apparent diffusion coefficient (ADC) values of the lesions in magnetic resonance imaging scans of treated glioblastoma patients to investigate if ADC values could accurately differentiate between tumor progression, radiation-related changes, and ischemic infarctions.

METHODS

We evaluated ADC values among 3 groups, patients with tumor progression, radiation necrosis, and ischemic infarctions. The regions of interest were placed in the areas of greatest hypointensity among solid lesions using the ADC maps, excluding areas with necrotic, cystic, or hemorrhagic changes. The ADC values of the contralateral normal appearing white matter were also measured as the reference value for each patient. The relative ADC (rADC) values were measured for all 3 groups. Comparison between lesions and normal white matter was evaluated by Wilcoxon signed test.

RESULTS

A total of 157 patients were included in the study; 49 patients classified as tumor progression, 58 patients as radiation necrosis, and 50 patients as ischemic infarctions. The mean ± SD ADC value was 752.8 ± 132.5 for tumor progression, 479.0 ± 105.2 for radiation-related changes, and 250.1 ± 57.2 for ischemic infarctions. The mean ± SD rADC value was 1.07 ± 0.22 for tumor progression, 0.66 ± 0.14 for radiation necrosis, and 0.34 ± 0.08 for ischemic infarctions. The mean rADC values were significantly higher in tumor progression, compared with both radiation necrosis and ischemic changes (P < 0.001).

CONCLUSIONS

The present study demonstrates that ADC values are a helpful tool to differentiate between tumor progression, radiation necrosis, and posttreatment ischemic changes.

Classification Algorithm-Based fMRI Images for Evaluating the Effect of Yishen Tiaodu Acupuncture on the Recovery Period of Cerebral Infarction

This study aimed to explore the application value of multifeature fusion classification algorithm based on deep learning and Yishen Tiaodu acupuncture in the diagnosis and treatment of patients with cerebral infarction in convalescence. Methods. 62 patients with cerebral infarction were randomly classified into the experimental group and the control group, with 31 patients in each group. All patients received the functional magnetic resonance imaging (fMRI) examination. The image processing method was the multifeature fusion classification algorithm based on deep learning. DICE coefficient, accuracy, and sensitivity were used to evaluate the image processing performance of traditional and new algorithms. Patients in the experimental group were treated with Yishen Tiaodu acupuncture, while patients in the control group were treated with ordinary acupuncture. The evaluation of the cyberchondria severity scale (CSS) and the activities of daily living (ADL) was performed at enrollment, 15 days after treatment, 28 days after treatment, and 1 month after treatment. The results showed that the quality of fMRI images processed by multifeature fusion classification algorithm based on deep learning was signally improved. The clinical efficacy of the traditional Chinese medicine (TCM) syndrome score (86.7% vs. 60.9%) and neurological impairment score (83.4% vs. 53.5%) in the experimental group were remarkably higher compared with the control group (P < 0.05). After treatment, the TCM syndrome score of the experimental group was markedly lower than that of the control group, while the ADL score was higher (P < 0.05). Conclusion. The performance of multifeature fusion classification algorithm based on deep learning in fMRI image processing of patients with cerebral infarction is better than that of traditional algorithms. Yishen Tiaodu acupuncture has a good therapeutic effect on the recovery of motor and neurological function in patients with cerebral infarction at convalescence.

Benefits of Endovascular Treatment in Late Window for Acute Ischemic Stroke Selected without CT Perfusion: A Real-World Study

Objective

This study examined the functional outcomes and safety of endovascular treatment (EVT) in acute ischemic stroke (AIS) patients owing to large vessel occlusion of the anterior circulation, presented during a late-time window (6–24 hours after last seen well (LSW)) in a real-world practice.

Methods

This was a retrospective analysis from a bi-center prospective cohort. According to the stroke treatment, patients with continuous Alberta Stroke Plan Early Aspect score (ASPECTS) ≥6 on non-contrast CT (NCCT) and moderate to good collateral state on CT angiography (CTA) were divided into EVT group and standard medical treatment (SMT) group. The primary outcome was the rate of functional independence (90-day mRS ≤2). Safety outcomes were the occurrence of symptomatic intracranial hemorrhage (sICH) and the 90-day mortality.

Results

Among the 288 enrolled patients (53.5% male, median age 64 years), there were 167 patients in the EVT group and 121 in the SMT group. After multivariable adjustments for potential confounders, EVT was associated with functional independence (adjusted OR: 3.052; 95% confidence interval (CI): 1.553–5.997; p = 0.001). In the PSM cohort, 44.2% (42/95) of patients in the EVT group versus 18.9% (18/95) in the SMT group achieved functional independence (OR: 3.39, 95% CI: 1.763–6.517), and there was a significant difference favoring EVT over the SMT in the overall distribution of mRS (OR: 2.170, 95% CI: 1.302–3.618) at 90 days. The rate of sICH did not differ between the EVT and SMT groups (10.5% vs 8.4%, p = 0.804) nor did 90-day mortality (18.9% vs 22.1%, p = 0.719). No interaction was found in p-values with statistical significance in subgroup analysis.

Conclusion

This real-world experience suggests that EVT for late-presenting stroke patients, based on small core on NCCT and moderate to good collaterals on CTA, is associated with better outcomes than SMT alone, with no increase in sICH and 90-day mortality rates.

Application of advanced magnetic resonance imaging in glaucoma: a narrative review

Glaucoma is a group of eye diseases characterized by progressive degeneration of the optic nerve head and retinal ganglion cells and corresponding visual field defects. In recent years, mounting evidence has shown that glaucoma-related damage may not be limited to the degeneration of retinal ganglion cells or the optic nerve head. The entire structure of the visual pathway may be degraded, and the degradation may even extend to some non-visual brain regions. We know that advanced morphological, functional, and metabolic magnetic resonance technologies provide a means to observe quantitatively and in real time the state of brain function. Advanced magnetic resonance imaging (MRI) techniques provide additional diagnostic markers for glaucoma, which are related to known potential histopathological changes. Many researchers in China and globally have conducted clinical and imaging studies on glaucoma. However, they are scattered, and we still need to systematically sort out the advanced MRI related to glaucoma. We reviewed literature published in any language and included all studies that were able to be translated into English from 1 January 1980 to 31 July 2021. Our literature search focused on emerging magnetic resonance neuroimaging techniques for the study of glaucoma. We then identified each functional area of the brain of glaucoma patients through the integration of anatomy, image, and function. The aim was to provide more information about the occurrence and development of glaucoma diseases. From the perspective of neuroimaging, our study provides a research basis to explain the possible mechanism of the occurrence and development of glaucoma. This knowledge gained from these techniques enables us to more clearly observe the damage glaucoma causes to the whole visual pathway. Our study provides new insights into glaucoma-induced changes to the brain. Our findings may enable the progress of these changes to be analyzed and inspire new neuroprotective therapeutic strategies for patients with glaucoma in the future.

pH-Responsive Multifunctional Theranostic Rapamycin-Loaded Nanoparticles for Imaging and Treatment of Acute Ischemic Stroke

Stroke is the second leading cause of death globally and the most common cause of severe disability. Several barriers need to be addressed more effectively to treat stroke, including efficient delivery of therapeutic agents, rapid release at the infarct site, precise imaging of the infarct site, and drug distribution monitoring. The present study aimed to develop a bio-responsive theranostic nanoplatform with signal-amplifying capability to deliver rapamycin (RAPA) to ischemic brain tissues and visually monitor drug distribution. A pH-sensitive theranostic RAPA-loaded nanoparticle system was designed since ischemic tissues have a low-pH microenvironment compared with normal tissues. The nanoparticles demonstrated good stability and biocompatibility and could efficiently load rapamycin, followed by its rapid release in acidic environments, thereby improving therapeutic accuracy. The nano-drug-delivery system also exhibited acid-enhanced magnetic resonance imaging (MRI) and near-infrared fluorescence (NIRF) imaging signal properties, enabling accurate multimodal imaging with minimal background noise, thus improving drug tracing and diagnostic accuracy. Finally, in vivo experiments confirmed that the nanoparticles preferentially aggregated in the ischemic hemisphere and exerted a neuroprotective effect in rats with transient middle cerebral artery occlusion (tMCAO). These pH-sensitive multifunctional theranostic nanoparticles could serve as a potential nanoplatform for drug tracing as well as the treatment and even diagnosis of acute ischemic stroke. Moreover, they could be a universal solution to achieve accurate in vivo imaging and treatment of other diseases.

Circular RNA expression alteration and bioinformatics analysis in patients with acute cerebral infarction injury

In recent years, a steady increase has been detected in the incidence of acute cerebral infarction (ACI). ACI is caused by blood flow disruption, leading to high disability and mortality rates. Understanding the underlying molecular mechanisms is critical toward developing effective therapeutic approaches. Circular RNAs (circRNAs) are an important class of non-coding RNAs, which have been implicated in several molecular pathways, and their dysregulation has been described in several disease conditions. Here, we set out to explore the possible regulatory role of circRNAs in ischemic stroke and study their molecular function in disease. First, we applied high-throughput sequencing techniques to identify the differential changes of plasma circRNAs expression in patients with acute cerebral infarction. Next, we used GO and KEGG pathway analysis to predict the function of differentially expressed circRNAs. Moreover, we have assessed the possible interaction between the identified differentially expressed circRNAs and miRNAs. Finally, we have selected and validated five downregulated circRNAs by RT-qPCR. Together, the results of this study provide evidence that circRNAs are potential biomarkers for early diagnosis of cerebral infarction and have to be considered as targets for drug treatment.

Animal models of stroke

Stroke is a devastating disease with high morbidity and mortality. Animal models are indispensable tools that can mimic stroke processes and can be used for investigating mechanisms and developing novel therapeutic regimens. As a heterogeneous disease with complex pathophysiology, mimicking all aspects of human stroke in one animal model is impossible. Each model has unique strengths and weaknesses. Models such as transient or permanent intraluminal thread occlusion middle cerebral artery occlusion (MCAo) models and thromboembolic models are the most commonly used in simulating human ischemic stroke. The endovascular filament occlusion model is characterized by easy manipulation and accurately controllable reperfusion and is suitable for studying the pathogenesis of focal ischemic stroke and reperfusion injury. Although the reproducibility of the embolic model is poor, it is more convenient for investigating thrombolysis. Rats are the most frequently used animal model for stroke. This review mainly outlines the stroke models of rats and discusses their strengths and shortcomings in detail.

MRI tracking/detection of bone marrow mesenchymal stromal cells transplantation for treatment of ischemic cerebral infarction

Background

Cerebral stroke is the second leading cause of death with high mortality and morbidity worldwide, currently it lacks effective therapies to improve the prognosis. This study was aimed to explore the role of bone marrow mesenchymal stem cells (BMSCs) transplantation in the recovery of brain structure and function after ischemic cerebral infarction by magnetic resonance imaging (MRI).

Methods

By applying internal carotid artery embolization, the ischemic cerebral infarction model in rats was established. MRI was performed to detect the imaging changes in the brain tissue after modeling, and the successful modeling was evidenced by the presence of obvious high-signal infarct areas in the brain. BMSCs were then injected into the lateral ventricles of rats, and the recovery of brain tissue and function were quantitatively evaluated by T2-weighted image (T2WI) and voxel-based morphology (VBM) after 28 days.

Results

The results showed that BMSCs were cell subsets with multiple differentiation potentials. Deficits caused by Ischemic cerebral infarction were relieved by BMSCs transplantation, including increase in damaged cerebral tissue and recovery of cerebral function. In addition, the combined imaging technology of VBM and T2WI quantitatively revealed the effectiveness of BMSCs in repairing damaged brain tissue structure and function.

Conclusion

Taken together, the results revealed that the transplantation of BMSCs into the lateral ventricle was beneficial to repair the structure and function of the damaged brain tissue after ischemic cerebral infarction. Moreover, the combination of VBM and T2WI technology can detect the level of brain injury in ischemic cerebral infarction dynamically and noninvasively, and evaluate the recovery of structure and function of damaged brain tissue.

Twenty-four-hour real-time continuous monitoring of acute focal cerebral ischemia in rabbits based on magnetic inductive phase shift

BACKGROUND

As a serious clinical disease, ischemic stroke is usually detected through magnetic resonance imaging and computed tomography. In this study, a noninvasive, non-contact, real-time continuous monitoring system was constructed on the basis of magnetic induction phase shift (MIPS) technology. The "thrombin induction method", which conformed to the clinical pathological development process of ischemic stroke, was used to construct an acute focal cerebral ischemia model of rabbits. In the MIPS measurement, a "symmetric cancellation-type" magnetic induction sensor was used to improve the sensitivity and antijamming capability of phase detection.

METHODS

A 24-h MIPS monitoring experiment was carried out on 15 rabbits (10 in the experimental group and five in the control group). Brain tissues were taken from seven rabbits for the 2% triphenyl tetrazolium chloride staining and verification of the animal model.

RESULTS

The nonparametric independent-sample Wilcoxon rank sum test showed significant differences (p < 0.05) between the experimental group and the control group in MIPS. Results showed that the rabbit MIPS presented a declining trend at first and then an increasing trend in the experimental group, which may reflect the pathological development process of cerebral ischemic stroke. Moreover, TTC staining results showed that the focal cerebral infarction area increased with the development of time CONCLUSIONS: Our experimental study indicated that the MIPS technology has a potential ability of differentiating the development process of cytotoxic edema from that of vasogenic edema, both of which are caused by cerebral ischemia.

Low-Dose Activated Protein C Suppresses the Development of Cerebral Infarction and Neurological Deficits in Mice

BACKGROUND

A large prospective study previously reported that a higher plasma level of protein C (PC) was associated with a lower incidence of ischemic stroke.

OBJECTIVE

To investigate the neuroprotective properties of activated PC (APC) against acute ischemic stroke using the 3-vessel occlusion model.

METHODS

Male C57BL/6J mice received APC (human APC) at 0.25, 0.5, or 1.0 (low dose) or 2.0, 4.0, or 8.0 mg/kg (high dose). Edaravone (Eda) (1.0, 3.0, or 10 mg/kg, a neuroprotectant approved for use in Japan), albumin (2.0 mg/kg), heparin (100 or 600 U/kg), or saline was used as the control. The drug or control was administered intravenously twice in the initial 24 h or 5 times in 3 d, starting 5 min after the induction of ischemia.

RESULTS

Low-dose APC significantly reduced lesion volumes, not affecting the depth of ischemia. High-dose APC did not significantly reduce lesion volumes, causing hemorrhagic transformation in some cases. In the chronic phase, lesion volumes were significantly suppressed in the APC or Eda group, and only the APC group showed a significant attenuation of neurological deficits. The protease-activated receptor (PAR)-1 antagonist SCH79797, administered during preischemia, completely abolished APC-induced neuroprotection. The overshoot-like abrupt recovery in regional cerebral blood flow observed in the control in the initial reperfusion phase was significantly suppressed by the APC treatment, indicating that the cerebral autoregulation system, consisting of endothelial cells and blood-brain barrier functions, was preserved.

CONCLUSION

Low-dose APC, potentially via the PAR-1-dependent anti-inflammatory cascade, protects the brain against ischemic stroke without increasing the risk of hemorrhagic transformation or death.

Diffusion-weighted imaging in hypertrophic cardiomyopathy: association with high T2-weighted signal intensity in addition to late gadolinium enhancement

Diffusion-weighted imaging (DWI) has been confirmed to be associated with late gadolinium enhancement (LGE) in hypertrophic cardiomyopathy (HCM). In this context, we aimed to study whether DWI could reflect the active tissue injury and edema information of HCM which were usually indicated by T2 weighted images. Forty HCM patients were examined using a 3.0 T magnetic resonance scanner. Cine, T2-weighted short tau inversion recovery (T2-STIR), DWI and LGE sequences were acquired. T1 mapping was also included to quantify the focal and diffuse fibrosis. Cardiac troponin I (cTnI) was tested to assess the recently myocardial injury. Student's t-test, Mann-Whitney U test, One-way analysis, Kruskal-Wallis analysis, the Spearman correlation analysis, and multivariable regression were used in this study. The apparent diffusion coefficient (ADC) was significantly elevated in the cTnI positive group (P = 0.01) and correlated with LGE (ρ = 0.312, P = 0.049) and HighT2 extent (ρ = 0.443, P = 0.004) in the global level. In the segmental analysis, the ADC significantly differentiated the segments with and without HighT2/LGE presence (P = 0.00). The average ADC values were higher in segments with HighT2 and LGE coexistence than in those with only LGE presence (P < 0.05). Multivariable regression indicated that segmental HighT2 and LGE were both contributing factors to the ADC values. In this study of HCM, we confirmed that ADC as a molecular diffusion parameter reflects the replacement fibrosis of myocardium. Moreover, it also reveals edema extent and its association with serum cTnI.

Diffusion kurtosis imaging of microstructural changes in brain tissue affected by acute ischemic stroke in different locations

The location of an acute ischemic stroke is associated with its prognosis. The widely used Gaussian model-based parameter, apparent diffusion coefficient (ADC), cannot reveal microstructural changes in different locations or the degree of infarction. This prospective observational study was reviewed and approved by the Institutional Review Board of Xiamen Second Hospital, China (approval No. 2014002). Diffusion kurtosis imaging (DKI) was used to detect 199 lesions in 156 patients with acute ischemic stroke (61 males and 95 females), mean age 63.15 ± 12.34 years. A total of 199 lesions were located in the periventricular white matter (n = 52), corpus callosum (n = 14), cerebellum (n = 29), basal ganglia and thalamus (n = 21), brainstem (n = 21) and gray-white matter junctions (n = 62). Percentage changes of apparent diffusion coefficient (ΔADC) and DKI-derived indices (fractional anisotropy [ΔFA], mean diffusivity [ΔMD], axial diffusivity [ΔD_a], radial diffusivity ΔD_r, mean kurtosis [ΔMK], axial kurtosis [ΔK_a], and radial kurtosis [ΔK_r]) of each lesion were computed relative to the normal contralateral region. The results showed that (1) there was no significant difference in ΔADC, ΔMD, ΔD_a or ΔD_r among almost all locations. (2) There was significant difference in ΔMK among almost all locations (except basal ganglia and thalamus vs. brain stem; basal ganglia and thalamus vs. gray-white matter junctions; and brainstem vs. gray-white matter junctions. (3) The degree of change in diffusional kurtosis in descending order was as follows: corpus callosum > periventricular white matter > brainstem > gray-white matter junctions > basal ganglia and thalamus > cerebellum. In conclusion, DKI could reveal the differences in microstructure changes among various locations affected by acute ischemic stroke, and performed better than diffusivity among all groups.