High-Resolution MRI Vessel Wall Imaging in Acute Aneurysmal Subarachnoid Hemorrhage : Spatiotemporal Pattern and Clinicoradiologic Implications

Advanced cross-sectional imaging of cerebral aneurysms

While the rupture rate of cerebral aneurysms is only 1% per year, ruptured aneurysms are associated with significant morbidity and mortality, while aneurysm treatments have their own associated risk of morbidity and mortality. Conventional markers for aneurysm rupture include patient-specific and aneurysm-specific characteristics, with the development of scoring systems to better assess rupture risk. These scores, however, rely heavily on aneurysm size, and their accuracy in assessing risk in smaller aneurysms is limited. While the individual risk of rupture of small aneurysms is low, due to their sheer number, the largest proportion of ruptured aneurysms are small aneurysms. Conventional imaging techniques are valuable in characterizing aneurysm morphology; however, advanced imaging techniques assessing the presence of inflammatory changes within the aneurysm wall, hemodynamic characteristics of blood flow within aneurysm sacs, and imaging visualization of irregular aneurysm wall motion have been used to further determine aneurysm instability that otherwise cannot be characterized by conventional imaging techniques. The current manuscript reviews conventional imaging techniques and their value and limitations in cerebral aneurysm characterization, and evaluates the applications, value and limitations of advanced aneurysm imaging and post-processing techniques including intracranial vessel wall MRA, 4D-flow, 4D-CTA, and computational fluid dynamic simulations.

A comparison between different endovascular treatment strategies for acute large vessel occlusion due to intracranial artery atherosclerosis: data from ANGEL-ACT Registry

PURPOSE

The aim of our study is to compare the characteristics and clinical outcomes among the different endovascular treatment (EVT) strategies for large vessel occlusion underlying intracranial atherosclerosis (ICAS-LVO) in a recent nationwide registry.

METHODS

Patients with isolated ICAS-LVO were enrolled in our analysis and were categorized into three groups: first-line mechanical thrombectomy (MT) with rescue angioplasty and/or stenting (MT + RS), direct angioplasty and/or stenting without thrombectomy (DA), and MT alone. Baseline and periprocedural characteristics, successful recanalization, and 90-day functional outcomes were compared.

RESULTS

Of 396 patients with isolated ICAS-LVO in our study, successful recanalization was achieved in 94.5%, 100%, and 90.9% of patients in the MT + RS, DA, and MT groups, respectively. The 90-day functional independence in the three groups was 50.8%, 59.0%, and 45.1%. The main efficacy and safety outcomes showed no significant differences among the groups. First-pass recanalization (FPR) was more observed in the MT group (43.4%), the recanalization rate per attempt in the MT group gradually decreased until the fourth attempt, and further maneuvers showed recanalization rates of ≈0% per attempt. MT + RS (adjusted odds ratio [aOR] 0.10, p < 0.0001) and DA (aOR 0.18, p = 0.0013) were associated with lower FPR rate than MT alone in the multivariable logistic regression.

CONCLUSIONS

The technical feasibility and favorable outcomes of several EVT strategies for ICAS-LVO were established in our study. First-line MT with a bailout angioplasty is a reasonable option for ICAS-LVO, and DA is an effective option for the cases when ICAS-LVO is strongly suspected before EVT procedure.

Vasospasm: Role of Imaging in Detection and Monitoring Treatment

Cerebral vasospasm (VS) and delayed cerebral ischemia (DCI) are important complications of aneurysmal subarachnoid hemorrhage (ASAH). Imaging approaches to VS monitoring include noninvasive bedside assessment with transcranial Doppler ultrasonography, angiographic evaluation with digital subtraction angiography, and computed tomography (CT) angiography. DCI is a clinical diagnosis and is not fully explained by the presence of angiographic VS. CT perfusion has shown clinical utility and implications for future research in the evaluation of DCI in patients with ASAH. This review article discusses the common approaches to diagnosis and monitoring of VS and DCI, current treatment strategies, and future research directions.

Retrospective application of risk scores to ruptured intracranial aneurysms: would they have predicted the risk of bleeding?

As the incidental diagnosis of unruptured intracranial aneurysms has been increasing, several scores were developed to predict risk of rupture and growth to guide the management choice. We retrospectively applied these scores to a multicenter series of patients with subarachnoid hemorrhage to test whether they would have predicted the risk of bleeding in the event of aneurysm discovery previous to its rupture. Demographical, clinical, and radiological information of 245 adults were retrieved from two neurovascular centers' database. Data were pooled and PHASES, UCAS, and ELAPSS scores were retrospectively calculated for the whole population and their performances in identifying aneurysms at risk of rupture were compared. Mean PHASES, UCAS, and ELAPSS scores were 5.12 ± 3.08, 5.09 ± 2.62, and 15.88 ± 8.07, respectively. Around half (46%) of patients would have been assigned to the low- or very low-risk class (5-year rupture risk < 1%) in PHASES. Around 28% of patients would have been in a low-risk class, with a probability of 3-year rupture risk < 1% according to UCAS. Finally, ELAPSS score application showed a wider distribution among the risk classes, but a significant proportion of patients (45.5%) lie in the low- or intermediate-risk class for aneurysm growth. A high percentage of patients with ruptured aneurysms in this multicenter cohort would have been assigned to the lower risk categories for aneurysm growth and rupture with all the tested scores if they had been discovered before the rupture. Based on these observations, physicians should be careful about drawing therapeutic conclusions solely based on application of these scores.

Differences in Safety and Efficacy of Endovascular Treatment for Acute Ischemic Stroke : A Propensity Score Analysis of Intracranial Atherosclerosis-Related Occlusion versus Embolism

PURPOSE

The prognosis after endovascular treatment (EVT) of acute arterial occlusions due to intracranial atherosclerotic disease (ICAD) may differ from those due to embolism. The aim was to evaluate whether safety and efficacy of EVT differ among patients with middle cerebral artery (MCA) M1 occlusion from ICAD or embolism.

METHODS

A database review was conducted to identify EVT patients with acute MCA M1 occlusion from November 2013 to December 2018.The patients were divided into the ICAD group and embolic group according to the etiology of occlusion. Using propensity score analysis, patients with ICAD-related occlusion and embolism underwent 1:1 matching. Angiographic results, complications, and clinical outcomes were compared.

RESULTS

A total of 217 patients (ICAD: 51; embolism: 166) were identified. After propensity score matching, 45 patients with ICAD-related occlusion and 45 with embolism were matched. All baseline covariates except atrial fibrillation were statistically indistinguishable. The rate of successful reperfusion (modified Thrombolysis in Cerebral Infarction [mTICI] 2b-3) was similar between the two groups, while the rate of mTICI 3 in the ICAD group was higher. No statistical difference was observed in the rate of postprocedural intracranial hemorrhage. The rate of favorable outcome (modified Rankin Scale [mRS] ≤2) and mortality at 90 days was comparable.

CONCLUSION

This propensity score analysis demonstrated that the EVT patients with acute ICAD-related MCA M1 occlusion had similar angiographic and clinical outcomes compared to those with M1 embolism on a similar baseline condition.