Imaging of hemorrhagic stroke

Observation of the Therapeutic Effect of Dual Antiplatelet Therapy with Aspirin and Clopidogrel on the Incidence, Characteristics, and Outcome in Acute Ischemic Stroke Patients with Cerebral Microbleeds at a Teaching Hospital, China

Background

Cerebral microbleeds (CMBs) are an important risk factor for stroke recurrence and prognosis. However, there is no consensus on the safety of antiplatelet therapy in patients with ischemic stroke and CMBs.

Objective

This study aimed to observe the effects of dual antiplatelet therapy with aspirin and clopidogrel on bleeding conversion in patients with different degrees of CMBs.

Materials and Methods

An observational retrospective study was conducted on 160 patients with acute mild ischemic stroke admitted to the Stroke Center, Affiliated Hospital of Beihua University between March 2021 and December 2022. Patients were divided into the CMBs and non-CMB groups. The CMB group was then divided into the low, medium and high-risk groups. In two groups, all patients were administered dual antiplatelet therapy (aspirin 100 mg and clopidogrel 75 mg orally once a day for 21 days according to the Chinese Stroke Guidelines of 2018), and no other anticoagulant or antiplatelet drugs were administered during the treatment period. Head CT, National Institutes of Health Stroke Scale(NIHSS) and modified Rankin Scale (mRS) score were re-checked, and the number of bleeding conversions was calculated at 21 days.

Results

Five patients in the CMB group had intracranial hemorrhage (5/116, 4.3%), while no intracranial hemorrhage was observed in the non-CMB group. There were no differences in the conversion rate of cerebral hemorrhage, NIHSS score, or mRS score between two groups after dual antiplatelet therapy (p>0.05). The conversion rate of cerebral hemorrhage in the high-risk group was higher than that in the non-CMB group (p<0.05), but the NIHSS and mRS score showed no difference between the high-risk and non-CMB groups (p>0.05).

Conclusion

Dual antiplatelet therapy with aspirin and clopidogrel does not significantly increase the risk of bleeding transformation; however, it improves neurological recovery or long-term prognosis in patients with acute ischemic cerebral stroke complicated by low-risk and middle-risk CMBs.

A Review on Computer Aided Diagnosis of Acute Brain Stroke

Amongst the most common causes of death globally, stroke is one of top three affecting over 100 million people worldwide annually. There are two classes of stroke, namely ischemic stroke (due to impairment of blood supply, accounting for ~70% of all strokes) and hemorrhagic stroke (due to bleeding), both of which can result, if untreated, in permanently damaged brain tissue. The discovery that the affected brain tissue (i.e., 'ischemic penumbra') can be salvaged from permanent damage and the bourgeoning growth in computer aided diagnosis has led to major advances in stroke management. Abiding to the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) guidelines, we have surveyed a total of 177 research papers published between 2010 and 2021 to highlight the current status and challenges faced by computer aided diagnosis (CAD), machine learning (ML) and deep learning (DL) based techniques for CT and MRI as prime modalities for stroke detection and lesion region segmentation. This work concludes by showcasing the current requirement of this domain, the preferred modality, and prospective research areas.

MR-Imaging and Histopathological Diagnostic Work-Up of Patients with Spontaneous Lobar Intracerebral Hemorrhage: Results of an Institutional Prospective Registry Study

Intracerebral hemorrhage (ICH) is a frequently disabling or fatal disease. The localization of ICH often allows an etiological association. However, in atypical/lobar ICH, the cause of bleeding is less obvious. Therefore, we present prospective histopathological and radiological studies which were conducted within the diagnostic workup to identify causes for lobar ICH other than hypertension. From 2016 to 2018, 198 patients with spontaneous, non-traumatic ICH requiring neurosurgical monitoring were enrolled in an institutional prospective patient registry. Patients with deep-seated ICH and/or hemorrhagically transformed cerebral infarcts were excluded from further analysis. Data to evaluate the source of bleeding based on histopathological and/or radiological workup were prospectively evaluated and analyzed. After applying the inclusion criteria and excluding patients with incomplete diagnostic workup, a total of 52 consecutive patients with lobar ICH were further analyzed. Macrovascular disease was detected in 14 patients with lobar ICH (27%). In 11 patients, diagnostic workup identified cerebral amyloid angiopathy-related ICH (21%). In addition, five patients with tumor-related ICH (10%) and six patients with ICH based on infectious pathologies (11%) were identified. In four patients, the cause of bleeding remained unknown despite extensive diagnostic workup (8%). The present prospective registry study demonstrates a higher probability to identify a cause of bleeding other than hypertension in patients with lobar ICH. Therefore, a thorough diagnostic work-up in patients with ICH is essential to accelerate treatment and further improve outcome or prevent rebleeding.

Cortical Microinfarcts on 3T Magnetic Resonance Imaging in Cerebral Amyloid Angiopathy

Background and Purpose- Cerebral microinfarcts are small ischemic lesions that are found in cerebral amyloid angiopathy (CAA) patients at autopsy. The current study aimed to detect cortical microinfarcts (CMI) on in vivo 3 Tesla (3T) magnetic resonance imaging (MRI) in CAA patients, to study the progression of CMI over a 1-year period, and to correlate CMI with markers of CAA-related vascular brain injury and cognitive functioning. Methods- Thirty-five CAA patients (mean age, 74.2±7.6 years), 13 Alzheimer disease (AD) patients (67.0±5.8 years), and 26 healthy controls (67.2±9.5 years) participated in the study. All participants underwent a standardized clinical and neuropsychological assessment as well as 3T MRI. CMI were rated according to standardized criteria. Results- CMI were present in significantly more CAA patients (57.1%; median number: 1, range 1-9) than in Alzheimer disease (7.7%) or in healthy controls (11.5%; P<0.001). Incident CMI were observed after a 1-year follow-up. CMI did not correlate with any other MRI marker of CAA nor with cognitive function. Conclusions- In vivo CMI are a frequent finding on 3T MRI in CAA patients, and incident CMI are observable after 1-year follow-up. CMI can be regarded as a new MRI marker of CAA, potentially distinct from other well-established markers. Future larger cohort studies with longitudinal follow-up are needed to elucidate the relationship between CMI and possible causes and clinical outcomes in CAA.

Effects of antiplatelet therapy on stroke risk by brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases: subgroup analyses of the RESTART randomised, open-label trial

BACKGROUND

Findings from the RESTART trial suggest that starting antiplatelet therapy might reduce the risk of recurrent symptomatic intracerebral haemorrhage compared with avoiding antiplatelet therapy. Brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases (such as cerebral microbleeds) are associated with greater risks of recurrent intracerebral haemorrhage. We did subgroup analyses of the RESTART trial to explore whether these brain imaging features modify the effects of antiplatelet therapy.

METHODS

RESTART was a prospective, randomised, open-label, blinded-endpoint, parallel-group trial at 122 hospitals in the UK that assessed whether starting antiplatelet therapy might reduce the risk of recurrent symptomatic intracerebral haemorrhage compared with avoiding antiplatelet therapy. For this prespecified subgroup analysis, consultant neuroradiologists masked to treatment allocation reviewed brain CT or MRI scans performed before randomisation to confirm participant eligibility and rate features of the intracerebral haemorrhage and surrounding brain. We followed participants for primary (recurrent symptomatic intracerebral haemorrhage) and secondary (ischaemic stroke) outcomes for up to 5 years (reported elsewhere). For this report, we analysed eligible participants with intracerebral haemorrhage according to their treatment allocation in primary subgroup analyses of cerebral microbleeds on MRI and in exploratory subgroup analyses of other features on CT or MRI. The trial is registered with the ISRCTN registry, number ISRCTN71907627.

FINDINGS

Between May 22, 2013, and May 31, 2018, 537 participants were enrolled, of whom 525 (98%) had intracerebral haemorrhage: 507 (97%) were diagnosed on CT (252 assigned to start antiplatelet therapy and 255 assigned to avoid antiplatelet therapy, of whom one withdrew and was not analysed) and 254 (48%) underwent the required brain MRI protocol (122 in the start antiplatelet therapy group and 132 in the avoid antiplatelet therapy group). There were no clinically or statistically significant hazards of antiplatelet therapy on recurrent intracerebral haemorrhage in primary subgroup analyses of cerebral microbleed presence (2 or more) versus absence (0 or 1) (adjusted hazard ratio [HR] 0·30 [95% CI 0·08-1·13] vs 0·77 [0·13-4·61]; pinteraction=0·41), cerebral microbleed number 0-1 versus 2-4 versus 5 or more (HR 0·77 [0·13-4·62] vs 0·32 [0·03-3·66] vs 0·33 [0·07-1·60]; pinteraction=0·75), or cerebral microbleed strictly lobar versus other location (HR 0·52 [0·004-6·79] vs 0·37 [0·09-1·28]; pinteraction=0·85). There was no evidence of heterogeneity in the effects of antiplatelet therapy in any exploratory subgroup analyses (all pinteraction>0·05).

INTERPRETATION

Our findings exclude all but a very modest harmful effect of antiplatelet therapy on recurrent intracerebral haemorrhage in the presence of cerebral microbleeds. Further randomised trials are needed to replicate these findings and investigate them with greater precision.

FUNDING

British Heart Foundation.

Minimally Invasive Evacuation of Spontaneous Cerebellar Intracerebral Hemorrhage

OBJECTIVE

Spontaneous cerebellar intracerebral hemorrhage (scICH) constitutes ∼10% of all cases of spontaneous ICH, with a mortality of 20%-50%. Suboccipital craniectomy (SOC) is commonly performed for scICH causing brainstem compression or hydrocephalus. However, SOC requires long anesthesia times and results in a high complication rate. We present a series of patients who minimally invasive scICH evacuation as an alternative to traditional SOC.

METHODS

We retrospectively reviewed the operative records for patients presenting to a single center from January 1, 2009 to March 1, 2017. All patients who had undergone evacuation of scICH were included in the present study. Clinical and radiographic variables were collected, including admission and postoperative Glasgow coma scale (GCS) scores, preoperative and postoperative hematoma volumes, and modified Rankin scale (mRS) scores at long-term follow-up.

RESULTS

We identified 10 patients who had presented with scICH requiring surgery. All scICH evacuations were performed through a minicraniectomy positioned in the suboccipital area as close to the hematoma as possible. The mean patient age was 64.1 years. The mean presenting GCS score was 8.6, the mean initial hematoma volume was 25.4 mL, the mean procedure time was 57 minutes, and the mean postoperative hematoma volume was 2.8 mL. The mortality rate was 10% and mean long-term follow-up mRS score was 2.

CONCLUSIONS

Minimally invasive scICH hematoma evacuation is a feasible alternative to SOC with numerous advantages that could lead to improved radiographic and clinical results.

PItcHPERFeCT: Primary Intracranial Hemorrhage Probability Estimation using Random Forests on CT

INTRODUCTION

Intracerebral hemorrhage (ICH), where a blood vessel ruptures into areas of the brain, accounts for approximately 10-15% of all strokes. X-ray computed tomography (CT) scanning is largely used to assess the location and volume of these hemorrhages. Manual segmentation of the CT scan using planimetry by an expert reader is the gold standard for volume estimation, but is time-consuming and has within- and across-reader variability. We propose a fully automated segmentation approach using a random forest algorithm with features extracted from X-ray computed tomography (CT) scans.

METHODS

The Minimally Invasive Surgery plus rt-PA in ICH Evacuation (MISTIE) trial was a multi-site Phase II clinical trial that tested the safety of hemorrhage removal using recombinant-tissue plasminogen activator (rt-PA). For this analysis, we use 112 baseline CT scans from patients enrolled in the MISTE trial, one CT scan per patient. ICH was manually segmented on these CT scans by expert readers. We derived a set of imaging predictors from each scan. Using 10 randomly-selected scans, we used a first-pass voxel selection procedure based on quantiles of a set of predictors and then built 4 models estimating the voxel-level probability of ICH. The models used were: 1) logistic regression, 2) logistic regression with a penalty on the model parameters using LASSO, 3) a generalized additive model (GAM) and 4) a random forest classifier. The remaining 102 scans were used for model validation.For each validation scan, the model predicted the probability of ICH at each voxel. These voxel-level probabilities were then thresholded to produce binary segmentations of the hemorrhage. These masks were compared to the manual segmentations using the Dice Similarity Index (DSI) and the correlation of hemorrhage volume of between the two segmentations. We tested equality of median DSI using the Kruskal-Wallis test across the 4 models. We tested equality of the median DSI from sets of 2 models using a Wilcoxon signed-rank test.

RESULTS

All results presented are for the 102 scans in the validation set. The median DSI for each model was: 0.89 (logistic), 0.885 (LASSO), 0.88 (GAM), and 0.899 (random forest). Using the random forest results in a slightly higher median DSI compared to the other models. After Bonferroni correction, the hypothesis of equality of median DSI was rejected only when comparing the random forest DSI to the DSI from the logistic (p < 0.001), LASSO (p < 0.001), or GAM (p < 0.001) models. In practical terms the difference between the random forest and the logistic regression is quite small. The correlation (95% CI) between the volume from manual segmentation and the predicted volume was 0.93 (0.9,0.95) for the random forest model. These results indicate that random forest approach can achieve accurate segmentation of ICH in a population of patients from a variety of imaging centers. We provide an R package (https://github.com/muschellij2/ichseg) and a Shiny R application online (http://johnmuschelli.com/ich_segment_all.html) for implementing and testing the proposed approach.

The use of ADSCs as a treatment for chronic stroke

Stroke is one of the disorders for which clinically effective therapeutic modalities are most needed, and numerous ways have been explored to attempt to investigate their feasibilities. However, ischemic- or hemorrhagic-induced inflammatory neuron death causes irreversible injuries and infarction regions, and there are currently no truly effective drugs available as therapy. It is therefore urgent to be able to provide a fundamental treatment method to regenerate neuronal brain cells, and therefore, the use of stem cells for curing chronic stroke could be a major breakthrough development. In this review, we describe the features and classification of stroke and focus on the benefits of adipose tissue-derived stem cells and their applications in stroke animal models. The results show that cell-based therapies have resulted in significant improvements in neuronal behaviors and functions through different molecular mechanisms, and no safety problems have so far arisen after transplantation. Further, we propose a clinical possibility to create a homing niche by reducing the degree of invasive intracerebroventricular transplantation and combining it with continuous intravenous administration to achieve a complete cure.

Automatic quantification of subarachnoid hemorrhage on noncontrast CT

BACKGROUND AND PURPOSE

Quantification of blood after SAH on initial NCCT is an important radiologic measure to predict patient outcome and guide treatment decisions. In current scales, hemorrhage volume and density are not accounted for. The purpose of this study was to develop and validate a fully automatic method for SAH volume and density quantification.

MATERIALS AND METHODS

The automatic method is based on a relative density increase due to the presence of blood from different brain structures in NCCT. The method incorporates density variation due to partial volume effect, beam-hardening, and patient-specific characteristics. For validation, automatic volume and density measurements were compared with manual delineation on NCCT images of 30 patients by 2 radiologists. The agreement with the manual reference was compared with interobserver agreement by using the intraclass correlation coefficient and Bland-Altman analysis for volume and density.

RESULTS

The automatic measurement successfully segmented the hemorrhage of all 30 patients and showed high correlation with the manual reference standard for hemorrhage volume (intraclass correlation coefficient = 0.98 [95% CI, 0.96-0.99]) and hemorrhage density (intraclass correlation coefficient = 0.80 [95% CI, 0.62-0.90]) compared with intraclass correlation coefficient = 0.97 (95% CI, 0.77-0.99) and 0.98 (95% CI, 0.89-0.99) for manual interobserver agreement. Mean SAH volume and density were, respectively, 39.3 ± 31.5 mL and 62.2 ± 5.9 Hounsfield units for automatic measurement versus 39.7 ± 32.8 mL and 61.4 ± 7.3 Hounsfield units for manual measurement. The accuracy of the automatic method was excellent, with limits of agreement of -12.9-12.1 mL and -7.6-9.2 Hounsfield units.

CONCLUSIONS

The automatic volume and density quantification is very accurate compared with manual assessment. As such, it has the potential to provide important determinants in clinical practice and research.

Imaging of stroke: a comparison between X-ray fluorescence and magnetic resonance imaging methods

A dual imaging approach, combining magnetic resonance imaging to localize lesions and synchrotron rapid scanning X-ray fluorescence (XRF) mapping to localize and quantify calcium, iron and zinc was used to examine one case of recent stroke with hemorrhage and two cases of ischemia 3 and 7 years before death with the latter showing superficial necrosis. In hemorrhagic lesions, more Fe is found accompanied with less Zn. In chronic ischemic lesions, Fe, Zn and Ca are lower indicating that these elements are removed as the normal tissue dies and scar tissue forms. Both susceptibility and T2* maps were calculated to visualize iron in hemorrhages and validated by XRF Ca and Fe maps. The former was superior for imaging iron in hemorrhagic transformation and necrosis but did not capture ischemic lesions. In contrast, T2* could not differentiate Ca from Fe in necrotic tissue but did capture ischemic lesions, complementing the susceptibility mapping. The spatial localization, accurate quantitative data and elemental differentiation shown here could also be valuable for imaging other brain tissue damage with abnormal Ca and Fe content.

The role of imaging studies for evaluation of stroke in children

Stroke is a major cause of morbidity and mortality in children and long-term neurological deficits. Although cerebrovascular disorders occur less often in children than in adults, recognition of stroke in children has probably increased because of the widespread application of noninvasive diagnostic studies such as magnetic resonance imaging and computed tomography.Computed tomography (CT) should be the first imaging choice in the emergency setting when stroke is suspected. It will show the presence of hemorrhage (eg, bleeding from arteriovenous malformation). It is often normal within the first hours in arterial ischemic stroke. As in adults, magnetic resonance imaging is the neuroimaging modality to confirm the clinical diagnosis of ischemic stroke. In children, however, magnetic resonance imaging requires sedation and may not be as readily available as CT. Perfusion imaging demonstrates flow within the brain and can detect areas that are at risk of ischemia; however, further studies in the pediatric population need to be validated for this technique in children. Angiography detects arterial disease (eg, aneurysm); however, its use has been largely superseded by better magnetic resonance angiography, which is sensitive enough to visualize lesions in the proximal anterior cerebral artery, middle cerebral artery, and distal internal carotid artery (ICA). Magnetic resonance imaging using diffusion- weighted imaging is the most versatile and sensitive imaging technique for identifying ischemic lesions. In the future, we need to identify the pediatric patient presenting to the emergency department with an acute stroke and develop a pathway for the use of particular imaging techniques (eg, CT vs magnetic resonance imaging).