Flow alteration surgery using a radial artery graft for recurrent ruptured vertebral artery dissecting aneurysm after stent-assisted coil embolization: A case report.

BACKGROUND: Ruptured vertebral artery dissecting aneurysm (VADA) is often treated surgically with coil embolization and sometimes recurs. We herein report a case of recurrent ruptured VADA after stent-assisted coil embolization (SAC) that was successfully treated with flow alteration surgery using a radial artery (RA) graft. CASE DESCRIPTION: A 67-year-old woman presented with headache and coma. Enhanced CT revealed subarachnoid hemorrhage due to right VADA. Since the left VA was hypoplastic, the aneurysm was treated with SAC. However, follow-up angiography revealed recurrence of the aneurysm. Additional embolization was not considered due to the small size of the recurrent lesion and the presence of a stent; therefore, flow alteration surgery was performed using a RA graft. There were no neurological deficits after surgery or recurrence. CONCLUSION: Flow alteration surgery using a RA graft is useful for recurrent VADA after SAC.

Compatibility of the semijailing technique with extremely soft i-ED coils for ruptured blood blister-like and dissecting aneurysms: patient series.

BACKGROUND: Optimal treatment options for ruptured blood blister-like aneurysms (BBAs) and dissecting aneurysms (DAs) have not yet been established. Endovascular treatment may achieve vessel reconstruction with the preservation of antegrade blood flow; however, securing curative hemostasis at the fragile rupture point remains a major concern. OBSERVATIONS: Two ruptured BBAs and two ruptured DAs treated by stent-assisted coiling with the semijailing technique in the last 2 years are described herein. The devices used were braided stents and i-ED coils, which are new low-memory shape and extremely soft coils. Neither rebleeding nor ischemic complications were observed. All patients had a favorable outcome and showed no recurrence after treatment. LESSONS: All aneurysms were treated without ischemic complications or rebleeding. The good compatibility of braided stents and the new concept coils in stent-assisted coiling by the semijailing technique provides insight into these intractable hemorrhagic vascular pathologies.

High signal intensity of the intraaneurysmal sac on T1 CUBE imaging as a predictor of aneurysm stability after coil embolization.

OBJECTIVE: Histopathological studies of aneurysms after coil embolization showed that thrombus formation during the first month after endovascular treatment (EVT) played an important role in the healing process. The authors hypothesized that dedicated T1-weighted imaging may be used to predict stable aneurysms by visualizing the thrombus status within coil-treated aneurysms. Therefore, this study investigated the relationship between the signal intensity (SI) of the intraaneurysmal sac after coil embolization and aneurysm stability. METHODS: The study population included 82 patients with 86 aneurysms who underwent T1-weighted 3D black-blood fast spin-echo (T1 CUBE) imaging within 1 month after coil embolization between 2019 and 2022. The relative SI of a coil-treated aneurysm (RSIcoiled) was calculated as follows: the mean SI of the intraaneurysmal sac/the mean SI of the genu of the corpus callosum. Aneurysms with enlarged remnants on MR angiography (MRA) within 6 months after EVT were defined as recurrence, while a decrease of intraaneurysmal flow on MRA was defined as improved embolization status. Stable aneurysms were defined as improvement or no change in embolization status 6 months after coil embolization. The volume embolization ratio (VER) was calculated as the ratio of the packed coil volume to the aneurysm volume. Differences between stable and recurrent aneurysms were examined. All aneurysms were divided into high and low RSIcoiled groups based on the cutoff value of RSIcoiled, and differences between the two groups were also evaluated. RESULTS: Recurrence was confirmed for 26 of 86 aneurysms. A univariable analysis showed that small aneurysms, high VER, and high RSIcoiled were associated with aneurysm stability. In the receiver operating characteristic curve analysis, the optimal cutoff value for RSIcoiled to differentiate stable from recurrent aneurysms was 0.54. The cutoff value for RSIcoiled was selected as 0.50 (sensitivity 0.77, specificity 0.70) because it was half the value of the SI of the corpus callosum and close to the optimal cutoff value. In a multivariable analysis, RSIcoiled > 0.50 (OR 8.1, 95% CI 2.5-27) remained a significant factor for aneurysm stability. The high RSIcoiled group showed a higher rate of an improved embolization status (26% vs 6.1%, p = 0.022) and stable aneurysms (85% vs 15%, p = 0.0002). CONCLUSIONS: RSIcoiled was associated with postcoiling aneurysm stability. High RSIcoiled might imply intraaneurysmal thrombus formation associated with the healing process of coil-treated aneurysms.

Distribution of osteoprotegerin in unruptured intracranial aneurysms in humans: association with aneurysm wall protective remodeling.

OBJECTIVE: Aneurysm wall inflammation is associated with lesion instability in unruptured intracranial aneurysms (UIAs). However, most UIAs remain unruptured during lifelong follow-ups because of simultaneous protective remodeling against the inflammatory response. The protective effects of osteoprotegerin (OPG) in intracranial and abdominal aortic aneurysms have been suggested using rodent models; however, the role of this protein in UIAs in humans remains unclear. Herein, the authors examined the relationship between OPG expression and aneurysm wall integrity in intraoperatively resected UIAs by using immunohistochemical and immunofluorescence staining. METHODS: Sixteen UIA wall tissue specimens resected between 2017 and 2022 were analyzed. Aneurysm growth was defined as an enlargement > 1 mm or an obvious morphological change over the course of more than 6 months. Three high-power fields were randomly selected from areas expressing high and low levels of OPG within the same aneurysm. To clarify the role of OPG in the human aneurysm wall, the authors compared averaged values for the following pathological features between the 2 OPG expression groups: aneurysm wall thickness, collagen, macrophages, smooth muscle cells, and transforming growth factor beta 1 (TGF-ß1). Immunohistochemical staining within the entire tissue area was also analyzed to determine the relationships between OPG expression and different aneurysm growth patterns. Pathological findings were compared between high and low OPG expression levels using the Wilcoxon signed-rank test. RESULTS: The heterogeneous expression of OPG was detected in the walls of UIAs. Lesions expressing high OPG levels had thicker aneurysm walls (327 vs 180 µm, p = 0.002) and higher expression levels of TGF-ß1 (8.5% vs 5.4%, p = 0.002) than those expressing low OPG levels. The expression of TGF-ß1 was colocalized with that of OPG mainly in the tunica media. Furthermore, lesions expressing high OPG levels had larger α-SMA+ areas (25% vs 13%, p = 0.002). Aneurysm growth was observed in 6 of 9 UIAs with available data: whole sac expansion in 4 and secondary aneurysm formation in 2. Among the 6 UIAs with aneurysm growth, OPG expression was relatively higher in the UIAs with an internal elastic lamina than in those without (17% vs 6.9%). CONCLUSIONS: Aneurysm wall integrity was associated with OPG expression in the aneurysm wall. Collectively, the study results indicated that OPG is associated with protective remodeling, which may contribute to the retention of aneurysm wall structures.

Headache characteristics to screen for cervicocerebral artery dissection in patients with acute onset unusual headache.

OBJECTIVES: The aim of this preplanned primary analysis was to investigate the clinical manifestations of headache to screen for CAD patients with acute onset headache only. BACKGROUND: Spontaneous cervicocerebral artery dissection (CAD) with acute onset headache is not rare in clinical practice; however, it is underdiagnosed. On the other hand, subsequent infarction or subarachnoid hemorrhage mainly occurs within 1 week of headache onset. METHODS: Between April 2017 and January 2022, we conducted a single-center, cross-sectional retrospective study on 197 consecutive referred patients from neurosurgical outpatient clinics with acute onset unusual headache (stronger or longer headache than usual). All patients underwent magnetic resonance imaging to screen for secondary headache and were diagnosed based on the diagnostic protocol. We examined patient background data and the following headache characteristics: distribution, condition at the onset of headache, accompanying vomiting or nausea, worsening headache, and analgesic effects against headache. These factors were analyzed to identify independent diagnostic predictors of CAD. In this study, the rate of missing data was 41% for improvement of headache by analgesia and multiple imputation by chained equations was performed. RESULTS: A total of 93 patients (46 men and 47 women; mean age: 48 years, range: 25-73 years) were diagnosed with CAD. Univariate logistic regression analysis showed CAD was associated with current smoking, systolic blood pressure >140 mmHg, unilateral headache, worsening headache, and no headache improvement by analgesia. Unilateral, worsening headache and no headache improvement by analgesia remained independent diagnostic predictors in multivariable logistic regression after multiple imputation. No headache improvement by analgesia had the highest sensitivity (86%), while worsening headache had the highest specificity (84%). CONCLUSIONS: CAD needs to be considered in patients with unilateral, worsening headache and no headache improvement by analgesia.

Association of circumferential aneurysm wall enhancement with recurrence after coiling of unruptured intracranial aneurysms: a preliminary vessel wall imaging study.

OBJECTIVE: Recent histopathological studies of unruptured intracranial aneurysms (UIAs) have confirmed that aneurysm wall enhancement (AWE) on MR vessel wall imaging (VWI) is related to wall degeneration with in vivo inflammatory cell infiltration. Therefore, pretreatment aneurysm wall status on VWI may be associated with recurrence after endovascular treatment. METHODS: VWI with gadolinium was performed on 67 consecutive saccular UIAs before endovascular treatment between April 2017 and June 2021. The mean (range) follow-up period after treatment was 24.4 (6-54) months. AWE patterns were classified as circumferential AWE (CAWE), focal AWE (FAWE), and negative AWE (NAWE). The authors retrospectively investigated the relationship between aneurysm recurrence and AWE patterns, as well as conventional risk factors. RESULTS: Sixty-seven patients with 67 saccular UIAs were eligible for the present study. AWE patterns were as follows: 10 CAWE (14.9%), 20 FAWE (29.9%), and 37 NAWE (55.2%). Follow-up MRA detected aneurysm recurrence in 18 of 69 cases (26.1%). Univariate analysis identified maximum diameter (mean ± SD 5.8 ± 2.2 mm in patients with stable aneurysms vs 7.7 ± 3.8 mm in those with unstable aneurysms, p = 0.02), aspect ratio (1.4 ± 0.5 vs 1.1 ± 0.4, p < 0.01), aneurysm location in posterior circulation (4.1% vs 27.8%, p < 0.01), volume embolization ratio (29.6% ± 7.8% vs 25.2% ± 6.1%, p = 0.02), and AWE pattern (p = 0.04) as significant predictive factors of recurrence. Among the 3 AWE patterns, CAWE was significantly more frequent in the unstable group, but no significant differences in stability of the treated aneurysms were observed with the FAWE and NAWE patterns. In multivariate logistic regression analysis, CAWE pattern (OR 14.2, 95% CI 1.8-110.8, p = 0.01) and volume embolization ratio ≥ 25% (OR 8.6, 95% CI 2.1-34.3, p < 0.01) remained as significant factors associated with aneurysm stability after coiling. CONCLUSIONS: VWI before coiling provides novel insights into the stability of treated aneurysms. Aneurysms with the CAWE pattern on VWI before coiling may be less stable after treatment.

The impact of high-resolution cone-beam CT findings on decision-making for the treatment of unruptured middle cerebral artery aneurysms.

Even with the advent of endovascular treatment for intracranial aneurysms, microsurgical clipping continues to play a significant role in the treatment of middle cerebral artery (MCA) aneurysms. Securing perforators around unruptured intracranial aneurysms (UIAs) is essential for minimizing procedural risks in each treatment option. Therefore, we herein investigated whether the findings of high-resolution cone-beam computed tomography (HR-CBCT) have an impact on decision-making for the treatment of MCA UIAs. Patients with MCA UIAs between October 2017 and September 2021 were consecutively recruited for this study. All patients underwent HR-CBCT and 3D-DSA before treatment. The imaging quality of both modalities to visualize the microvasculature around aneurysms was evaluated. Specific findings on the microvasculature surrounding aneurysms on HR-CBCT were investigated to facilitate microsurgical clipping. Fifty-two MCA UIAs were treated, including 43 by microsurgical clipping and 9 by endovascular approaches. The overall imaging quality of HR-CBCT was superior to that of 3D-DSA. Regarding microsurgical insights, sensitivity and specificity for the visualization of small vessels around aneurysms were 79 and 100%, respectively, using HR-CBCT, and 57 and 93%, respectively, using 3D-DSA. The presence of a low-density band between adhesive vessels and aneurysm sacs was indicative of successful and safe microsurgical dissection between these structures. HR-CBCT enabled visualization of the intracranial microvasculature around MCA UIAs at the submillimeter level in vivo. In cases in which the tight adhesion of the microvasculature to the aneurysm sac is indicated by HR-CBCT, an endovascular approach may be considered in order to avoid the risks associated with securing perforators.

Diagnostic accuracy of MR vessel wall imaging at 2 weeks to predict morphological healing of vertebral artery dissection.

OBJECTIVES: The spontaneous healing of non-hemorrhagic intracranial vertebral artery dissection (VAD) may be associated with the stabilization of intramural hematoma (IMH). We previously suggested that the signal intensity of IMH increases until approximately 2 weeks in VAD with spontaneous healing. We herein investigated the diagnostic accuracy of the signal intensity of IMH at 2 weeks to predict the spontaneous healing of VAD. METHODS: From April 2017 to April 2021, we prospectively investigated patients with non-hemorrhagic VAD who underwent vessel wall imaging (VWI). Morphological healing of VAD was evaluated by MR angiography three months after its onset. The relative signal intensity (RSI) of IMH against the posterior cervical muscle on VWI was calculated. Univariate and multivariate analyses were performed on factors associated with the spontaneous healing of VAD among patient baseline data, vascular morphology at the diagnosis, and RSI parameters. RESULTS: Forty-eight patients (23 men and 25 women; mean age: 51 years, range: 34-73 years) with 50 non-hemorrhagic VAD were included in the present study. Spontaneous healing was observed in 28 VAD (56%). RSI two weeks after the onset of VAD (RSI2w) and morphological feature such as the string sign were associated with spontaneous healing, respectively. The multivariate logistic regression analysis identified RSI2w as an independent predictive factor of spontaneous healing (OR: 7.3; 95% CI, 1.9-28, p = 0.004). The cut-off value for RSI2w to predict spontaneous healing was 1.22 (AUC = 0.90, sensitivity: 91%, specificity: 82%). CONCLUSION: RSI2w predicted the spontaneous healing of non-hemorrhagic VAD 3 months after its onset.

Association of Neutrophil Extracellular Traps with Plaque Instability in Patient with Carotid Artery Stenosis.

BACKGROUND: Vulnerable carotid plaques are related to cerebral thromboembolic and ischemic events. Neutrophil extracellular traps (NETs) can induce endothelial dysfunction and induce inflammation and coagulation. The aim of the present study was to investigate NETs in patients with carotid artery plaques. METHODS: Carotid plaques were collected by carotid endarterectomy (CEA) from 26 symptomatic and 8 asymptomatic patients between August 2017 and January 2021. The specimens were stained with hematoxylin-eosin and Elastica-van Gieson. Immunohistochemistry was performed staining by CD31 for identifying endothelial cells. NETs were detected by digoxigenin-labeled antihistone H3 (HH3) (citrulline R2+R8+R17). The relationships between the presence of NETs and patient profile and histopathological findings were assessed. RESULTS: HH3-positive cells were detected in 17 (asymptomatic = 2 symptomatic = 15) of 34 carotid plaques (median = 9.7/mm). The number of NETs was correlated with the number of diffusion-weighted imaging high-intensity lesions [P = 0.01], plaque rupture [P = 0.001], intraplaque hemorrhage [P = 0.02], intra luminal thrombus [P = 0.001], and thin fibrous cap [P = 0.001]. CONCLUSIONS: The presence of NETs was associated with the instability of carotid plaques, intraluminal thrombus, which may lead to subsequent cerebral infarction. Clarifying the roles of NETs in carotid plaques may improve the treatment of carotid artery disease.

Segmentation of aneurysm wall enhancement in evolving unruptured intracranial aneurysms.

OBJECTIVE: Morphological changes in unruptured intracranial aneurysms (UIAs) are an imaging marker of aneurysm instability. Recent studies have indicated the ability of MR vessel wall imaging (VWI) to stratify unstable UIAs based on a correlation with histopathological aneurysm wall inflammation. In the present study the authors investigated the relationships between aneurysm growth patterns and the segmentation of aneurysm wall enhancement (AWE) in VWI. METHODS: A total of 120 aneurysms with serial angiography from a follow-up period of at least 2 years (mean 65 months, range 24-215 months) were assessed by VWI. Two readers independently evaluated the patterns of morphological changes (stable, whole sac expansion, and secondary aneurysm formation) and the segmentation of AWE (no, focal, and circumferential AWE). The contrast enhancement ratio of the aneurysm wall versus the pituitary stalk (CRstalk) was calculated for the quantitative assessment of AWE. Statistical analyses were performed to investigate the relationships between AWE patterns and patient baseline profiles, aneurysm characteristics, and morphological modifications. RESULTS: Forty-one of 120 UIAs (34%) exhibited aneurysm growth (whole sac expansion in 19 and secondary aneurysm formation in 22). AWE was detected in 35 of 120 UIAs (focal AWE in 25 and circumferential AWE in 10). The maximum diameter of, irregularities in, and morphological modifications in aneurysms were associated with the segmentation of AWE. Focal AWE correlated with secondary aneurysm formation, and circumferential AWE correlated with whole sac expansion. In focal AWE, CRstalk was significantly higher in secondary aneurysm formation than in stable UIAs. UIAs without AWE (categorized as no AWE) correlated with aneurysm stability. CONCLUSIONS: The segmentation of AWE was associated with aneurysm growth scenarios and may provide a novel insight into the evaluation of unstable UIAs.

Monitoring Intramural Hematoma on Vessel Wall Imaging to Evaluate the Healing of Intracranial Vertebral Artery Dissection.

OBJECTIVE: Unruptured intracranial vertebral artery dissection (VAD) generally heals spontaneously. A chronological evaluation of intramural hematoma (IMH) using T1-weighted vessel wall imaging (VWI) may provide a more detailed understanding of the pathophysiology of VAD. We herein investigated the relationship between chronological signal changes in IMH on VWI and the spontaneous healing of VAD. MATERIALS AND METHODS: We retrospectively investigated 26 patients with 27 unruptured VADs who underwent magnetic resonance (MR) imaging more than three times during the follow-up period. Morphological changes were evaluated using MR angiography (MRA). The relative signal intensity (RSI) of IMH against the posterior cervical muscle on T1-weighted VWI was calculated. The ratio of chronological RSI changes was defined as follows: maximum RSI/minimum RSI (RSI max/min). Based on the median value of RSI max/min, 27 VADs were divided into VADs with and without chronological RSI changes. Statistical analyses were performed to compare clinical and radiological findings between the two groups. RESULTS: Spontaneous healing occurred in 17 out of 27 VADs (63%). The median value of RSI max/min was 1.48. The RSI of VADs with chronological RSI changes (RSI max/min ≥ 1.48) increased until three weeks after their onset and decreased over time, while that of VADs without chronological RSI changes (RSI max/min < 1.48) showed no change. The frequency of healing was significantly higher in VADs with than without chronological RSI changes (100% vs 23%, p < 0.0001). CONCLUSIONS: Chronological signal changes in IMH on T1-weighted VWI have potential as a diagnostic imaging marker of the spontaneous healing of VAD.

Peptidylarginine Deiminase 4 as a Possible Biomarker of Plaque Instability in Carotid Artery Stenosis.

BACKGROUND AND PURPOSE: Neutrophil extracellular traps (NETs) exhibit pro-inflammatory and pro-thrombotic properties. However, they have only been reported as important regulators in atherosclerosis, especially in atherothrombosis. We investigated the presence of NETs and plaque instability in patients with carotid artery stenosis. MATERIAL AND METHODS: A total of 39 consecutive patients with carotid artery stenosis were evaluated. All patients underwent carotid artery stenting (CAS) with dual protection (simultaneous flow reversal + distal filter) and blood aspiration as a method of distal embolism prevention. Local arterial blood was aspirated at the stent site and peptidylarginine deiminase 4 (PAD4), which is essential for the formation of NETs, was measured. The relationships between PAD4 and the patient profile, blood examination and plaque data were investigated. RESULTS: The mean value of PAD4 in local arterial blood in CAS was 0.5 ng/ml. Bivariate analysis demonstrated that PAD4 was associated with the neutrophil to lymphocyte ratio (p = 0.007), high-density lipoprotein (p = 0.02), triglycerides to high-density lipoprotein ratio (p = 0.007), ulceration (p = 0.02) and plaque contrast enhancement on T1 black blood imaging (p = 0.03). In multiple linear regression analyses, PAD4 was correlated with the neutrophil to lymphocyte ratio (p = 0.01) and ulceration (p = 0.01, cut-off value: 0.49 odds ratio: 19.3). CONCLUSIONS: PAD4, representative of the presence of NETs, was high in carotid plaques with unstable features. The neutrophil to lymphocyte ratio in peripheral blood was suggested to be a biomarker of vulnerable plaques. Elucidating the role of NETs may aid in clarifying factors that promote the instability of carotid plaques.

Magnetic resonance vessel wall imaging predicts morphological deterioration in unruptured intracranial artery dissection.

OBJECTIVE: The mechanism involved in progression of unruptured intracranial artery dissection (IAD) is poorly understood. We investigated the relationship between contrast enhancement of dissecting lesions on magnetic resonance vessel wall imaging (MR-VWI) and unruptured IAD progression on the hypothesis that this finding might predict its instability. METHODS: A total of 49 unruptured IADs were investigated retrospectively. Three-dimensional T1-weighted fast spin-echo sequences were obtained before and after injection of contrast medium, and the dissecting lesion/pituitary stalk contrast enhancement ratio (CRstalk) was calculated. Unruptured IAD progression was defined as morphological deterioration; progressive dilatation or stenosis. The relations between unruptured IAD progression and potential risk factors were statistically investigated. RESULTS: Morphological deterioration was demonstrated in eleven of 49 unruptured IADs (22 %). The CRstalk value and male predominance was significantly higher in progressed IADs than stable ones (1.0 vs. 0.65; p = 0.0035, 82% vs 37%; p= 0.015, respectively). On stepwise multivariable logistic regression analysis, the CRstalk value was independently associated with unruptured IAD progression with odds ratio of 102.5 (95% CI, 2.59-4059, P=0.0013). The optimal cutoff value of CRstalk to estimate IADs with progression was 0.87 (sensitivity, 0.82; specificity, 0.74). Multimodalic images showed contrast enhancement on VWI corresponded to residual stagnant flow in dissecting lesions. CONCLUSIONS: Quantitative analysis of contrast enhancement on VWI could predict instability of unruptured IADs. Contrast enhancement in dissecting lesions would be a clue to understand the mechanism of unruptured IAD progression.

Impact of Cone-Beam Computed Tomography Angiography on Visualization of Sylvian Veins.

BACKGROUND: A detailed understanding of the anatomy of Sylvian veins preoperatively is needed for venous-preserving Sylvian dissection. Better visualization of the venous architecture will facilitate surgical strategies for Sylvian dissection. This study evaluated and compared the image quality of the Sylvian veins and their tributaries using high-resolution cone-beam computed tomography angiography (CBCT-A) and three-dimensional computed tomography angiography (3D-CTA). METHODS: Twenty-four patients who underwent 3D-CTA and CBCT-A as a preoperative simulation for clipping of unruptured intracranial aneurysms were retrospectively reviewed. In comparisons with intraoperative inspections, 3 raters evaluated the image quality of the Sylvian veins by 3D-CTA and CBCT-A with a 5-point scale. Visualization of the Sylvian veins and their tributaries by the 2 imaging modalities was compared using Wilcoxon signed rank test. RESULTS: CBCT-A showed superior image quality to 3D-CTA in evaluations of the discrimination of adjacent superficial Sylvian veins (2.8 ± 0.80 vs. 4.6 ± 0.37, P < 0.0001), adjacent Sylvian veins at the sphenoid wing (3.1 ± 0.71 vs. 4.1 ± 0.56, P = 0.0001), and visualization of the tributaries of the Sylvian veins (2.5 ± 0.70 vs. 4.4 ± 0.37, P < 0.0001). CONCLUSIONS: CBCT-A was superior to 3D-CTA for visualizing the Sylvian veins and their tributaries. CBCT-A will provide important information on the anatomy of the Sylvian veins preoperatively.

Lessons from Vessel Wall Imaging of Intracranial Aneurysms: New Era of Aneurysm Evaluation beyond Morphology.

Recent basic studies have clarified that aneurysmal wall inflammation plays an important role in the pathophysiology of intracranial aneurysms. However, it remains an interdisciplinary challenge to visualize aneurysm wall status in vivo. MR-vessel wall imaging (VWI) is a current topic of advanced imaging techniques since it could provide an additional value for unruptured intracranial aneurysms (UIAs) risk stratification. With regard to ruptured intracranial aneurysms, VWI could identify a ruptured aneurysm in patients with multiple intracranial aneurysms. Intraluminal thrombus could be a clue to interpret aneurysm wall enhancement on VWI in ruptured intracranial aneurysms. The interpretation of VWI findings in UIAs would require much caution. Actually aneurysm wall enhancement in VWI was significantly associated with consensus morphologic risk factors. However, aneurysmal wall with contrast enhancement oftentimes associated with atherosclerotic, degenerated and thickened wall structure. It remains ill defined if thin wall without wall enhancement (oftentimes invisible in VWI) could be actually safe or look over wall vulnerability. We reviewed currently available studies, especially focusing on VWI for intracranial aneurysms and discussed the clinical utility of VWI.

Vessel Wall Imaging Predicts the Presence of Atherosclerotic Lesions in Unruptured Intracranial Aneurysms.

BACKGROUND: Recent studies have suggested that magnetic resonance vessel wall imaging (VWI) can visualize thickened intracranial aneurysm wall. We aimed to investigate correlations between VWI findings and intraoperative aneurysm wall features based on the hypothesis that VWI can visualize atherosclerotic changes in unruptured intracranial aneurysm (UIA) walls. METHODS: A total of 36 microsurgically treated UIAs were retrospectively reviewed. All aneurysms underwent VWI before microsurgical clipping, and fusion images with time-of-flight magnetic resonance angiography were created to localize aneurysm wall enhancement (AWE) lesions. Intraoperatively, 2 neurosurgeons who were blinded to the VWI findings evaluated the aneurysm wall features, giving each aneurysm an atherosclerosis score on a 5-point scale (5: yellowish, 4: whitish, 3: normal, 2: slightly reddish, 1: reddish). We defined atherosclerotic lesions as those having average scores ≥4. We evaluated the rate of correspondence between AWE lesions and atherosclerotic lesions, and the factors associated with AWE. RESULTS: Sixteen of the 36 UIAs (44%) were identified as AWE. The sensitivity, specificity, positive predictive value, and negative predictive value of correspondence between AWE lesions and atherosclerotic lesions were 79%, 94%, 94%, and 80%, respectively. The average atherosclerosis scores (4.2 ± 0.5 vs. 2.7 ± 0.9; P < 0.001) were significantly higher in aneurysms with AWE. Twelve of 16 UIAs with wall enhancement had wall thinning adjacent to the part with AWE. CONCLUSIONS: AWE lesions corresponded with intraoperatively confirmed atherosclerotic lesions of UIAs. Detecting these lesions would be valuable in exploring UIAs with wall degeneration.

Vessel Wall Imaging of Evolving Unruptured Intracranial Aneurysms.

Background and Purpose- Unruptured intracranial aneurysms (UIAs) have various scenarios of growth and rupture. Magnetic resonance vessel wall imaging can detect aneurysmal wall thickening with inflammation and neovascularization. This study was performed to explore the vessel wall imaging findings of UIAs with consecutive follow-up. Methods- A total of 60 aneurysms with serial angiography over 2 years (mean period, 49 months, range, 24-192 months) were evaluated by vessel wall imaging. UIAs were morphologically categorized into 3 patterns: stable, whole sac expansion, or daughter sac formation. Aneurysm wall enhancement (AWE) was evaluated after administration of gadolinium. Results- Thirty-three of the 60 UIAs (55%) demonstrated no morphological changes, whereas 16 UIAS (27%) showed whole sac expansion and 11 UIAs (18%) demonstrated daughter sac formation. AWE was significantly less frequent in stable UIAs compared with UIAs showing morphological changes ( P<0.01). Aneurysms with daughter sac formation showed a significantly higher frequency of AWE than those demonstrating whole sac expansion. In the majority of UIAs with daughter sac formation, AWE was detected in the main aneurysm and not in the developing component. Conclusions- UIAs demonstrate various modes of growth. The pattern of AWE might be useful for identifying unfavorable morphological changes of UIAs.

Focal Aneurysm Wall Enhancement on Magnetic Resonance Imaging Indicates Intraluminal Thrombus and the Rupture Point.

BACKGROUND: The precise mechanism of aneurysm wall enhancement (AWE) in ruptured intracranial aneurysms on magnetic resonance vessel wall imaging (VWI) remains unclear. We explored patterns of VWI findings and correlations with intraoperative or histopathologic aneurysm wall architecture. METHODS: Twenty-four patients were evaluated by VWI before microsurgical clipping or endovascular coiling. The patterns of AWE were categorized, and the contrast ratio of AWE area was measured relative to the pituitary stalk. A total of 13 aneurysms were microsurgically inspected of the aneurysm wall and 4 were available for histopathologic evaluation. RESULTS: AWE was identified in 20 of 24 ruptured aneurysms. Among these 20 aneurysms, AWE was focal in 15 and circumferential in 5. Focal AWE showed significantly higher contrast ratio than circumferential AWE (P = 0.002). Histopathologic studies suggested that focal AWE indicating contrast ratio over 0.1 could be associated with fresh intraluminal thrombus at the rupture site. On the contrary, circumferential AWE suggested potential wall thickening with abundant neovascularization and inflammatory cells. CONCLUSIONS: Two AWE patterns were seen in ruptured intracranial aneurysms. Focal AWE on magnetic resonance imaging might indicate the presence of intraluminal thrombus, and detection of this sign could be useful for identification of the rupture point before treatment.

Hyperperfusion after Endovascular Reperfusion Therapy for Acute Ischemic Stroke.

BACKGROUND AND PURPOSE: Patients with acute ischemic stroke (AIS) may display prolonged neurological deficits and conscious disturbance even after successful endovascular thrombectomy. We hypothesized that hemodynamic change after reperfusion might influence outcomes. This study investigated the factors causing hyperperfusion and outcomes. METHODS: We retrospectively analyzed 27 patients with AIS who underwent successful acute revascularization (TICI: Thrombolysis in Cerebral Infarction 2b + 3). Changes of the neurological status were precisely assessed by using the National Institutes of Health Stroke Scale (NIHSS). Ischemic lesions were scored by MRI with diffusion-weighted imaging (DWI), and blood flow in the middle cerebral artery territory was assessed by MRI with arterial spin labeling. Univariate analysis was performed to investigate correlations between hyperperfusion and demographic factors or the functional prognosis. RESULTS: Thirteen of the 27 (48%) patients developed hyperperfusion after reperfusion. A significant correlation was seen between hyperperfusion and the improvement of NIHSS at 24 hours (P < .0001), the duration of disturbance of consciousness (days) (P < .0001), DWI-ASPECTS (P = .001), hemorrhagic transformation (P = .007), and mRS less than or equal to 2 at 90 days (P = .007). CONCLUSIONS: The present findings suggested that some patients with AIS will develop hyperperfusion after successful acute revascularization. The status of hyperperfusion could prolong conscious disturbance and affect outcomes. Since the mechanism of hyperperfusion after revascularization depends on stroke etiology, diagnosing the type of ischemic stroke in the acute stage is important for managing postoperative treatment.