Quantitative Susceptibility Mapping and Vessel Wall Imaging as Screening Tools to Detect Microbleed in Sentinel Headache

Radiomics-Based Predictive Nomogram for Assessing the Risk of Intracranial Aneurysms

Aneurysm wall enhancement (AWE) has the potential to be used as an imaging biomarker for the risk stratification of intracranial aneurysms (IAs). Radiomics provides a refined approach to quantify and further characterize AWE's textural features. This study examines the performance of AWE quantification combined with clinical information in detecting symptomatic IAs. Ninety patients harboring 104 IAs (29 symptomatic and 75 asymptomatic) underwent high-resolution magnetic resonance imaging (HR-MRI). The assessment of AWE was performed using two different methods: 3D-AWE mapping and composite radiomics-based score (RadScore). The dataset was split into training and testing subsets. The testing set was used to build two different nomograms using each modality of AWE assessment combined with patients' clinical information and aneurysm morphological data. Finally, each nomogram was evaluated on an independent testing set. A total of 22 radiomic features were significantly different between symptomatic and asymptomatic IAs. The 3D-AWE mapping nomogram achieved an area under the curve (AUC) of 0.77 (63% accuracy, 78% sensitivity, and 58% specificity). The RadScore nomogram exhibited a better performance, achieving an AUC of 0.83 (77% accuracy, 89% sensitivity, and 73% specificity). The comprehensive analysis of IAs with the quantification of AWE data through radiomic analysis, patient clinical information, and morphological aneurysm metrics achieves a high accuracy in detecting symptomatic IA status.

Radiomics-Based Predictive Nomogram for Assessing the Risk of Intracranial Aneurysms

Background

Aneurysm wall enhancement (AWE) has the potential to be used as an imaging biomarker for the risk stratification of intracranial aneurysms (IAs). Radiomics provides a refined approach to quantify and further characterize AWE's textural features. This study examines the performance of AWE quantification combined with clinical information in detecting symptomatic IAs.

Methods

Ninety patients harboring 104 IAs (29 symptomatic and 75 asymptomatic) underwent high-resolution magnetic resonance imaging (HR-MRI). The assessment of AWE was performed using two different methods: 3D-AWE mapping and composite radiomics-based score (RadScore). The dataset was split into training and testing subsets. The testing set was used to build two different nomograms using each modality of AWE assessment combined with patients' demographic information and aneurysm morphological data. Finally, each nomogram was evaluated on an independent testing set.

Results

A total of 22 radiomic features were significantly different between symptomatic and asymptomatic IAs. The 3D-AWE Mapping nomogram achieved an area under the curve (AUC) of 0.77 (63% accuracy, 78% sensitivity and 58% specificity). The RadScore nomogram exhibited a better performance, achieving an AUC of 0.83 (77% accuracy, 89% sensitivity and 73% specificity).

Conclusions

Combining AWE quantification through radiomic analysis with patient demographic data in a clinical nomogram achieved high accuracy in detecting symptomatic IAs.

MRI of unruptured infectious intracranial aneurysms in infective endocarditis. A case-control study

PURPOSE

To evaluate the usefulness of T2* and FLAIR sequences in the detection of unruptured infectious intracranial aneurysms (UIIAs) in infective endocarditis (IE) including the relationships between the lesion patterns within subarachnoid spaces and the presence of UIIA.

METHODS

Retrospective review of 15 consecutive patients with definite IE undergoing MR imaging (FLAIR, T2*, DWI, CE-MRA, 3D-T1, CE-3DT1 sequences), in whom DSA detected infectious intracranial aneurysms (IIA). Aneurysmal features (diameter, location, morphology on DSA) and signal patterns onT2*, FLAIR and conventional MR sequences at the site of the UIIA, follow-up MRI and IE background, were analyzed. A control-group of 15 IE-patients without IIA at DSA served for comparison.

RESULTS

Among 17 UIIAs studied, T2* sequence displayed a susceptibility vessel sign in 15/17 (88.2%), both distal and proximal, which matched with the IIA visualized on DSA. Three patterns of hyposignal areas were identified: (a) signet-ring or target-sign appearance (n = 7), (b) homogeneous, round-, oval- or pear-shaped area (n = 4), and (c) heterogeneous area (n = 4). A FLAIR hyperintensity of the lumen and of the adjacent cortex was present in 6 (35.3%) and 9 (53%) UIIAs, respectively. On T1 (12 UIIAs) a rounded hyposignal (n = 2), within the UIIA lumen matched with the FLAIR hypersignal. Using both T2* and FLAIR had an incremental value with 100% sensitivity and specificity.

CONCLUSION

The susceptibility vessel sign is an MR imaging pattern frequently observed at the site of UIIAs in IE-patients. Both T2* and FLAIR may have the potential to depict UIIAs, regardless of their location and shape.

Feasibility and intra-and interobserver reproducibility of quantitative susceptibility mapping with radiomic features for intracranial dissecting intramural hematomas and atherosclerotic calcifications

Quantitative susceptibility mapping (QSM) for 61 patients with dissecting intramural hematomas (n = 36) or atherosclerotic calcifications (n = 25) in intracranial vertebral arteries were collected to assess intra- and interobserver reproducibility in a 3.0-T MR system between January 2015 and December 2017. Two independent observers each segmented regions of interest for lesions twice. The reproducibility was evaluated using intra-class correlation coefficients (ICC) and within-subject coefficients of variation (wCV) for means and concordance correlation coefficients (CCC) and ICC for radiomic features (CCC and ICC > 0.85) were used. Mean QSM values were 0.277 ± 0.092 ppm for dissecting intramural hematomas and - 0.208 ± 0.078 ppm for atherosclerotic calcifications. ICCs and wCVs were 0.885-0.969 and 6.5-13.7% in atherosclerotic calcifications and 0.712-0.865 and 12.4-18.7% in dissecting intramural hematomas, respectively. A total of 9 and 19 reproducible radiomic features were observed in dissecting intramural hematomas and atherosclerotic calcifications, respectively. QSM measurements in dissecting intramural hematomas and atherosclerotic calcifications were feasible and reproducible between intra- and interobserver comparisons, and some reproducible radiomic features were demonstrated.

Diagnostic criteria for acute headache attributed to ischemic stroke and for sentinel headache before ischemic stroke

Background

Defining the relationship between a headache and stroke is essential. The current diagnostic criteria of the ICHD-3 for acute headache attributed to ischemic stroke are based primarily on the opinion of experts rather than on published clinical evidence based on extensive case-control studies in patients with first-ever stroke. Diagnostic criteria for sentinel headache before ischemic stroke do not exist. The present study aimed to develop explicit diagnostic criteria for headache attributed to ischemic stroke and for sentinel headache.

Methods

This prospective case-control study included 550 patients (mean age 63.1, 54% males) with first-ever ischemic stroke and 192 control patients (mean age 58.7, 36% males) admitted to the emergency room without any acute neurological deficits or severe disorders. Standardized semi-structured interview forms were used to evaluate past and present headaches during face-to-face interviews by a neurologist on admission to the emergency room in both groups of patients. All headaches were diagnosed according to the ICHD-3. We tabulated the onset of different headaches before a first-ever ischemic stroke and at the time of onset of stroke. We divided them into three groups: a new type of headache, the previous headache with altered characteristics and previous unaltered headaches. The same was done for headaches in control patients within one week before admission to the hospital and at the time of entry. These data were used to create and test diagnostic criteria for acute headache attributed to stroke and sentinel headache.

Results

Our previous studies showed that headache at onset of ischemic stroke was present in 82 (14.9%) of 550 patients, and 81 (14.7%) patients had sentinel headache within the last week before a stroke. Only 60% of the headaches at stroke onset fulfilled the diagnostic criteria of ICHD-3. Therefore, we proposed alternative criteria with a sensitivity of 100% and specificity of 97%. Besides, we developed diagnostic criteria for sentinel headache for the first time with a specificity of 98% and a sensitivity of 100%.

Conclusions

We suggest alternative diagnostic criteria for acute headache attributed to ischemic stroke and new diagnostic criteria for sentinel headache with high sensitivity and specificity.

Warning Signs in the Era of Unruptured Intracranial Aneurysms: Report on 2 Cases of Fatal Aneurysmal Hemorrhage

Introduction

The timing of treatment remains unresolved for patients with unruptured intracranial aneurysms (UIAs) and headaches, particularly when the pain is short term, localized, and related to the aneurysm site. We lack evidence to support the notion that when a headache accompanies an aneurysm, it elevates the risk of rupture.

Results

We describe 2 cases of fatal subarachnoid hemorrhage in patients with a history of headache and known aneurysms. Both of these patients had good indications for treatment: a young age and an aneurysm >7 mm, and both were qualified for elective surgery. However, both patients died of fatal aneurysm ruptures before the planned surgery.

Conclusion

These cases suggested that treatment should be started as soon as possible, when a UIA is diagnosed based on a short-term period of severe headaches or when a UIA is observed and then severe headaches appear. There is no straightforward guideline for treatment timing in these patients. However, in this era of UIAs, the significance of sentinel headaches should be reevaluated. Given the incidence of headaches in the general population and the very low risk of aneurysm rupture, there may be a tendency to neglect the role of headache as a possible warning sign.

Evaluating thunderclap headache

PURPOSE OF REVIEW

Thunderclap headache (TCH) is an abrupt-onset of severe headache that needs to be thoroughly investigated because the most common secondary cause is subarachnoid hemorrhage (SAH). There has been no consensus guideline regarding the diagnostic workup. This review aims to provide an update on the evaluation of TCH.

RECENT FINDINGS

The most important update in the 2019 American College of Emergency Physicians guideline for evaluation of acute headache in the emergency department is that negative noncontrast brain computed tomography (CT) findings within 6 h from ictus essentially excludes SAH. Additionally, the updated guideline recommends that after a negative brain CT, CT angiogram is a reasonable alternative to lumbar puncture if clinical suspicion of an intracranial source of SAH is high. An important update of reversible vasoconstriction syndrome (RCVS), the second most common etiology of TCH, is the RCVS2 score development based on clinical and radiological features, providing high specificity and sensitivity for distinguishing RCVS from other intracranial arteriopathies.

SUMMARY

Although the evaluation of TCH is exhaustive, the potentially catastrophic consequence of a missed diagnosis of sentinel headache justifies the efforts. Awareness of the clinical features and application of diagnostic tools specific for different pathological conditions can facilitate the diagnostic workup.

Predicting the Poor Recovery Risk of Aneurysmal Subarachnoid Hemorrhage: Clinical Evaluation and Management Based on a New Predictive Nomogram

PURPOSE

To develop and validate a model for identifying the risk factors of poor recovery in patients with aneurysmal subarachnoid hemorrhage (aSAH).

METHODS

A prediction model was developed using training data obtained from 1577 aSAH patients from multiple centers. The patients were followed for 6 months on average and assessed using the modified Rankin Scale; patient information was collected with a prospective case report form. The least absolute shrinkage and selection operator regression were applied to optimize factor selection for the poor recovery risk model. Multivariable logistic regression, incorporating the factors selected in the previous step, was used for model predictions. Predictive ability and clinical effectiveness of the model were evaluated using C-index, receiver operating characteristic curve, and decision curve analysis. Internal validation was performed using the C-index, taking advantage of bootstrapping validation.

RESULTS

The predictors included household income per capita, hypertension, smoking, migraine within a week before onset, Glasgow Coma Scale at admission, average blood pressure at admission, modified Fisher score at admission, treatment method, and complications. Our newly developed model made satisfactory predictions; it had a C-index of 0.796 and an area under the receiver operating characteristic curve of 0.784. The decision curve analysis showed that the poor recovery nomogram was of clinical benefit when an intervention was decided at a poor recovery threshold between 2% and 50%. Internal validation revealed a C-index of 0.760.

CONCLUSION

Our findings indicate that the novel poor recovery nomogram may be conveniently used for risk prediction in aSAH patients. For patients with intracranial aneurysms, migraine needs to be vigilant. Quitting smoking and blood pressure management are also beneficial.

Pathophysiology of Intracranial Aneurysms

Background and Purpose:

The pathophysiology of development, growth, and rupture of intracranial aneurysms (IAs) is only partly understood. Cyclooxygenase 2 (COX-2) converts arachidonic acid to prostaglandin H 2 , which, in turn, is isomerized to prostaglandin E 2 . In the human body, COX-2 plays an essential role in inflammatory pathways. This explorative study aimed to investigate COX-2 expression in the wall of IAs and its correlation to image features in clinical (1.0T, 1.5T, and 3.0T) magnetic resonance imaging (MRI) and ultra-high-field 7T MRI.

Methods:

The study group comprised 40 patients with partly thrombosed saccular IAs. The cohort included 17 ruptured- and 24 unruptured IAs, which had all been treated microsurgically. Formaldehyde-fixed paraffin-embedded samples were immunohistochemically stained with a monoclonal antibody against COX-2 (Dako, Santa Clara, CA; Clone: CX-294). We correlated Perls Prussian blue staining, MRI, and clinical data with immunohistochemistry, analyzed using the Trainable Weka Segmentation algorithm.

Results:

Aneurysm dome size ranged between 2 and 67 mm. The proportion of COX-2 positive cells ranged between 3.54% to 85.09%. An upregulated COX-2 expression correlated with increasing IA dome size ( P =0.047). Furthermore, there was a tendency of higher COX-2 expression in most ruptured IAs ( P =0.064). At all field strengths, MRI shows wall hypointensities due to iron deposition correlating with COX-2 expression ( P =0.022).

Conclusions:

Iron deposition and COX-2 expression in IAs walls correlate with signal hypointensity in MRI, which might, therefore, serve as a biomarker for IA instability. Furthermore, as COX-2 was also expressed in small unruptured IAs, it could be a potential target for specific medical treatment.