Detection of Dolichoectasia and Atherosclerosis by Automated MRA Tortuosity Metrics in a Population-Based Study

BACKGROUND

Intracranial vessel tortuosity is a key component of dolichoectasia and has been associated with atherosclerosis and adverse neurologic outcomes. However, the evaluation of tortuosity is mainly a descriptive assessment.

PURPOSE

To compare the performance of three automated tortuosity metrics (angle metric [AM], distance metric [DM], and distance-to-axis metric [DTA]) for detection of dolichoectasia and presence of segment-specific plaques.

STUDY TYPE

Observational, cross-sectional metric assessment.

POPULATION

1899 adults from the general population; mean age = 76 years, female = 59%, and black = 29%.

FIELD STRENGTH/SEQUENCE

3-T, three-dimensional (3D) time-of-flight MRA and 3D vessel wall MRI.

ASSESSMENT

Tortuosity metrics and mean luminal area were quantified for designated segments of the internal carotid artery, middle cerebral artery, anterior cerebral artery, posterior cerebral artery, vertebral artery, and entire length of basilar artery (BA). Qualitative interpretations of BA dolichoectasia were assessed based on Smoker's visual criteria.

STATISTICAL TESTS

Descriptive statistics (2-sample t-tests, Pearson chi-square tests) for group comparisons. Receiver operating characteristics area under the curve (AUC) for detection of BA dolichoectasia or segment-specific plaque. Model inputs included 1) tortuosity metrics, 2) mean luminal area, and 3) demographics (age, race, and sex).

RESULTS

Qualitative dolichoectasia was identified in 336 (18%) participants, and atherosclerotic plaques were detected in 192 (10%) participants. AM-, DM-, and DTA-calculated tortuosity were good individual discriminators of basilar dolichoectasia (AUCs: 0.76, 0.74, and 0.75, respectively), with model performance improving with the mean lumen area: (AUCs: 0.88, 0.87, and 0.87, respectively). Combined characteristics (tortuosity and mean luminal area) identified plaques with better performance in the anterior (AUCs ranging from 0.66 to 0.78) than posterior (AUCs ranging from 0.54 to 0.65) circulation, with all models improving by the addition of demographics (AUCs ranging from 0.62 to 0.84).

DATA CONCLUSION

Quantitative vessel tortuosity metrics yield good diagnostic accuracy for the detection of dolichoectasia.

LEVEL OF EVIDENCE

1 TECHNICAL EFFICACY STAGE: 2.

Verifying the Accuracy of Hemodynamic Analysis Using High Spatial Resolution 3D Phase-contrast MR Imaging on a 7T MR System: Comparison with a 3T System

PURPOSE

Hemodynamics is important in the initiation, growth, and rupture of intracranial aneurysms. Since intracranial aneurysms are small, a high-field MR system with high spatial resolution and high SNR is desirable for this hemodynamic analysis. The purpose of this study was to investigate whether the accuracy of MR fluid dynamic (MRFD) results based on 3D phase-contrast MR (3D PC MR, non-electrocardiogram[ECG]-gated 4D Flow MRI) data from a human cerebrovascular phantom and human healthy subjects obtained by a 7T MR system was superior to those by a 3T MR system.

METHODS

3D PC MR and 3D time of flight MR angiography (3D TOF MRA) imaging were performed on a 3T MR system and a 7T MR system for a human cerebrovascular phantom and 10 healthy human subjects, and MRFD analysis was performed using these data. The MRFD results from each MR system were then compared with the following items based on the computational fluid dynamics (CFD) results: 3D velocity vector field; correlation coefficient (R), angular similarity index (ASI), and magnitude similarity index (MSI) of blood flow velocity vectors.

RESULTS

In the MRFD results of 3D velocity vectors of the cerebrovascular phantom, noise-like vectors were observed near the vascular wall on the 3T MR system, but no noise was observed on the 7T MR system, showing results similar to those of CFD. In the MRFD results of the cerebrovascular phantom and healthy subjects, the correlation coefficients R, ASI, and MSI of the 7T MR system were higher than those of the 3T MR system, and ASI and MSI of healthy human subjects were significantly different between the two systems.

CONCLUSIONS

The accuracy of high spatial resolution MRFD using the 7T MR system exceeded that of the 3T MR system.

Optimizing contrast protocol for bone-subtraction CT angiography of intracranial arteries in normal dogs using 160-slice CT

BACKGROUND

Bone-subtraction computed tomography angiography (CTA) (BSCTA) is a new technique designed to overcome the limitation of three-dimensional CTA, where the vessels surrounded by bone and calcification can be obscured. An optimal contrast CT protocol for intracranial artery visualization with BSCTA has yet to be established in dogs.

OBJECTIVES

The purpose of this study was to determine the optimal contrast protocol of CTA for visualizing intracranial artery using an automatic bone-subtraction technique in dogs.

METHODS

Brain CTA was performed four times for each of nine healthy beagle dogs to cover all the contrast protocols: two different contrast iodine concentrations (300 and 370 mgI/mL) and two different contrast media injection rates (2 and 4 mL/s). Bone removal post-processing was performed automatically by subtracting the non-enhanced CT data from the contrast CT data using a dedicated workstation. The bone-subtracted intracranial vessels were analysed for quantitative and qualitative evaluation.

RESULTS

Quantitative evaluation showed significantly higher CT attenuation values for the group with a 370 mgI/mL iodine content at a rate of 4 mL/s than the two groups with a 300 mgI/mL iodine content at the rates of 2 and 4 mL/s (p < 0.001). Qualitative assessment revealed significantly higher mean scores for the 370 mgI/mL groups than the 300 mgI/mL groups and significantly higher mean scores for the 4 mL/s groups than the 2 mL/s groups (p < 0.05).

CONCLUSIONS

The optimal contrast protocol for BSCTA suggests that high iodine material concentration and high injection rate should be used for strong arterial attenuation and great visualization of the intracranial arterial structure in dogs.

Assessing Machine Learning Models for Predicting Age with Intracranial Vessel Tortuosity and Thickness Information

This study aimed to develop and validate machine learning (ML) models that predict age using intracranial vessels' tortuosity and diameter features derived from magnetic resonance angiography (MRA) data. A total of 171 subjects' three-dimensional (3D) time-of-flight MRA image data were considered for analysis. After annotations of two endpoints in each arterial segment, tortuosity features such as the sum of the angle metrics, triangular index, relative length, and product of the angle distance, as well as the vessels' diameter features, were extracted and used to train and validate the ML models for age prediction. Features extracted from the right and left internal carotid arteries (ICA) and basilar arteries were considered as the inputs to train and validate six ML regression models with a four-fold cross validation. The random forest regression model resulted in the lowest root mean square error of 14.9 years and the highest average coefficient of determination of 0.186. The linear regression model showed the lowest average mean absolute percentage error (MAPE) and the highest average Pearson correlation coefficient (0.532). The mean diameter of the right ICA vessel segment was the most important feature contributing to prediction of age in two out of the four regression models considered. An ML of tortuosity descriptors and diameter features extracted from MRA data showed a modest correlation between real age and ML-predicted age. Further studies are warranted for the assessment of the model's age predictions in patients with intracranial vessel diseases.

Vessel Wall Imaging of Intracranial Arteries: Fundamentals and Clinical Applications

With the increasing use of 3-tesla MRI scanners and the development of applicable sequences, it has become possible to achieve high-resolution, good contrast imaging, which has enabled the imaging of the walls of small-diameter intracranial arteries. In recent years, the usefulness of vessel wall imaging has been reported for numerous intracranial arterial diseases, such as for the detection of vulnerable plaque in atherosclerosis, diagnosis of cerebral arterial dissection, prediction of the rupture of cerebral aneurysms, and status of moyamoya disease and cerebral vasculitis. In this review, we introduce the histological characteristics of the intracranial artery, discuss intracranial vessel wall imaging methods, and review the findings of vessel wall imaging for various major intracranial arterial diseases.

Long noncoding RNA profile of the intracranial artery in patients with moyamoya disease

OBJECTIVE

Moyamoya disease (MMD) is a rare cerebrovascular disease characterized by progressive stenosis of the internal carotid artery (ICA) and secondary formation of collateral vessels. Revascularization surgery is performed in patients with MMD to prevent stroke; however, the pathogenesis of MMD remains unknown. Recently, long noncoding RNAs (lncRNAs) have been found to play a key role in gene regulation and are implicated in various vascular diseases. However, the lncRNA expression profile in MMD lesions has not been investigated. In this study the authors aimed to determine the characteristics of lncRNA expression in MMD lesions.

METHODS

The authors collected microsamples of the middle cerebral artery (MCA) from patients with MMD (n = 21) and patients with control conditions (n = 11) who underwent neurosurgical treatment. Using microarray experiments, the authors compared the profiles of lncRNA expression in the MCAs of the MMD and control patient groups and identified differentially expressed lncRNAs (fold change > 2, q < 0.05). In addition, the neighboring coding genes, whose transcription can be regulated in cis by the identified differentially expressed lncRNAs, were investigated and Gene Ontology (GO) analysis was applied to predict associated biological functions.

RESULTS

The authors detected 308 differentially expressed lncRNAs (fold change > 2, q < 0.05), including 306 upregulated and 2 downregulated lncRNAs in the MCA from patients with MMD. Regarding the prediction of biological function, GO analyses with possible coding genes whose transcription was regulated in cis by the identified differentially expressed lncRNAs suggested involvement in the antibacterial humoral response, T-cell receptor signaling pathway, positive regulation of cytokine production, and branching involved in blood vessel morphogenesis.

CONCLUSIONS

The profile of lncRNA expression in MMD lesions was different from that in the normal cerebral artery, and differentially expressed lncRNAs were identified. This study provides new insights into the pathophysiology of MMD.

Clinical and vascular features of stroke in Takayasu's arteritis: A 24-year retrospective study

Objective

To investigate the clinical characteristics, vascular imaging features, and prognosis of Takayasu's arteritis (TA) patients with stroke in China.

Methods

Medical charts of 411 in-patients who fulfilled the classification criteria of modified 1990 American College of Rheumatology (ACR) criteria for TA and with complete data from 1990 to 2014 were reviewed retrospectively. The demographic data, symptoms and signs, laboratory test results, radiological features, treatment, and interventional or surgical procedures were collected and analyzed. Patients with radiological confirmed stroke were identified. Chi-square test or Fisher exact test was used to compare the differences between patients with and without stroke.

Results

Twenty-two patients with ischemic stroke (IS) and 4 patients with hemorrhagic stroke were identified. The incidence of stroke in TA patients was 6.3% (26/411), of which 11 patients were considered to be the initial manifestation. Stroke patients had more visual acuity loss (15.4% vs. 4.7%, P = 0.042). Systemic inflammatory symptoms and inflammatory markers were less common in patients with stroke than in those without stroke [fever P = 0.007; erythrocyte sedimentation rate (ESR) or C-reactive protein (CRP), P < 0.001]. Cranial angiography showed that common carotid artery (CCA) (73.0%, 19/26) and subclavian artery (SCA) (73.0%, 19/26) were the most involved, followed by internal carotid artery (ICA) (57.7%, 15/26) in stroke patients. The intracranial vascular involvement rate of stroke patients was 38.5% (10/26); the middle cerebral artery (MCA) was the most common artery involved. The most common site of stroke was the basal ganglia region. The occurrence of intracranial vascular involvement was much higher in patients with stroke when compared to patients without stroke (38.5% vs. 5.5%, P < 0.001). Among all patients with intracranial vascular involvement, patients without stroke received more aggressive treatment than patients with stroke (90.4% vs. 20.0%, P < 0.001). There was no significant increase in in-hospital mortality in patients with stroke compared with patients without stroke (3.8% vs. 2.3%, P = 0.629).

Conclusion

Stroke is the initial presentation in 50% of TA patients with stroke. The intracranial vascular involvement rate is significantly increased in stroke patients than in patients without stroke. The artery invloved in patients with stroke are cervical artery and intracranial involvement. Systemic inflammation is less in patients with stroke. Aggressive treatment for TA with glucosteroid (GC) and immunosuppressive agents combined with anti-stroke therapy is needed to improve the prognosis of TA complicated stroke.

Dual Antiplatelet Therapy Using Cilostazol in Patients With Stroke and Intracranial Arterial Stenosis

Background Long-term benefit of dual antiplatelet therapy (DAPT) over single antiplatelet therapy (SAPT) for the prevention of recurrent stroke has not been established in patients with intracranial arterial stenosis. We compared the efficacy and safety of DAPT with cilostazol and clopidogrel or aspirin to those of SAPT with clopidogrel or aspirin in patients with intracranial arterial stenosis, who were recruited to the Cilostazol Stroke Prevention Study for Antiplatelet Combination trial, a randomized controlled trial in high-risk Japanese patients with ischemic stroke. Methods and Results We compared the vascular and hemorrhagic events between DAPT and SAPT in patients with ischemic stroke and symptomatic or asymptomatic intracranial arterial stenosis of at least 50% in a major intracranial artery. Patients were placed in two groups: 275 were assigned to receive DAPT and 272 patients SAPT. The risks of ischemic stroke (hazard ratio [HR], 0.47; 95% CI, 0.23-0.95); and composite of stroke, myocardial infarction, and vascular death (HR, 0.48; 95% CI, 0.26-0.91) were lower in DAPT than SAPT, whereas the risk of severe or life-threatening bleeding (HR, 0.72; 95% CI, 0.12-4.30) did not differ between the 2 treatment groups. Conclusions DAPT using cilostazol was superior to SAPT with clopidogrel or aspirin for the prevention of recurrent stroke and vascular events without increasing bleeding risk among patients with intracranial arterial stenosis after stroke. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT01995370.

Transcriptome-wide analysis of intracranial artery in patients with moyamoya disease showing upregulation of immune response, and downregulation of oxidative phosphorylation and DNA repair

OBJECTIVE

Moyamoya disease (MMD) is a rare cerebrovascular disease characterized by progressive occlusion of the internal carotid artery and the secondary formation of collateral vessels. Patients with MMD have ischemic attacks or intracranial bleeding, but the disease pathophysiology remains unknown. In this study, the authors aimed to identify a gene expression profile specific to the intracranial artery in MMD.

METHODS

This was a single-center, prospectively sampled, retrospective cohort study. Microsamples of the middle cerebral artery (MCA) were collected from patients with MMD (n = 11) and from control patients (n = 9). Using microarray techniques, transcriptome-wide analysis was performed.

RESULTS

Comparison of MCA gene expression between patients with MMD and control patients detected 62 and 26 genes whose expression was significantly (p < 0.001 and fold change > 2) up- or downregulated, respectively, in the MCA of MMD. Gene set enrichment analysis of genes expressed in the MCA of patients with MMD revealed positive correlations with genes involved in antigen processing and presentation, the dendritic cell pathway, cytokine pathway, and interleukin-12 pathway, and negative correlations with genes involved in oxidative phosphorylation and DNA repair. Microarray analysis was validated by quantitative polymerase chain reaction.

CONCLUSIONS

Transcriptome-wide analysis showed upregulation of genes for immune responses and downregulation of genes for DNA repair and oxidative phosphorylation within the intracranial artery of patients with MMD. These findings may represent clues to the pathophysiology of MMD.

Intracranial Atherosclerotic Plaque Characteristics and Burden Associated With Recurrent Acute Stroke: A 3D Quantitative Vessel Wall MRI Study

Background: Intracranial atherosclerotic disease (ICAD) tends to affect multiple arterial segments, and previous studies rarely performed a comprehensive plaque analysis of the entire circle of Willis for the evaluation of recurrent stroke risk. We aimed to investigate the features of circle of Willis ICAD on 3D magnetic resonance vessel wall imaging (MR-VWI) and their relationships with recurrent acute stroke. Methods: Patients with either acute ischemic stroke (within 4 weeks after stroke) or chronic ischemic stroke (after 3 months of stroke) due to intracranial atherosclerotic plaque underwent 3D contrast-enhanced MR-VWI covering major cerebral arteries. Participants were divided into three groups: first-time acute stroke, recurrent acute stroke, and chronic stroke. Culprit plaque (defined as the only lesion or the most stenotic lesion when multiple plaques were present within the same vascular territory of the stroke) and non-culprit plaque characteristics, including total plaque number, plaque thickness, plaque area, plaque burden (calculated as plaque area divided by outer wall area), enhancement ratio (ER), eccentricity, and stenosis, were measured and compared across the three groups. Associations between plaque characteristics and recurrent acute stroke were investigated by multivariate analysis. Results: A total of 176 participants (aged 61 ± 10 years, 109 men) with 702 intracranial plaques were included in this study. There were 80 patients with first-time acute stroke, 42 patients with recurrent acute stroke, and 54 patients with chronic stroke. More intracranial plaques were found per patient in the recurrent acute stroke group than in the first-time acute stroke or chronic stroke group (5.19 ± 1.90 vs. 3.71 ± 1.96 and 3.46 ± 1.33, p < 0.001). Patients in the recurrent acute stroke group had greater culprit plaque burden (p < 0.001) and higher culprit ER (p < 0.001) than the other two groups. After adjustment of clinical demographic factors, in multivariate analysis, coronary artery disease (CAD) (odds ratio, OR = 4.61; p = 0.035), total plaque number (OR = 1.54; p = 0.003), culprit plaque ER (OR = 2.50; p = 0.036), and culprit plaque burden (OR per 10% increment = 2.44; p = 0.010) were all independently associated with recurrent acute stroke compared to the first-time acute stroke. Conclusion: Increased intracranial atherosclerotic plaque number, higher culprit plaque ER, greater culprit plaque burden, and CAD are independently associated with recurrent acute stroke.

Usefulness of black-blood magnetic resonance angiography generated from vessel wall imaging after the stent-assisted treatment of intracranial arterial diseases

PURPOSE

After stent-assisted treatment for intracranial diseases, three-dimensional time-of-flight magnetic resonance angiography is a noninvasive follow-up method, but susceptibility artifacts prevent accurate evaluations of stented arteries. Sampling perfection with application-optimized contrast using different flip angle evolution (SPACE) sequence often used for vessel wall imaging is less susceptible to susceptibility artifacts, since it is a spin-echo sequence. Hence, we evaluated the feasibility of black-blood magnetic resonance angiography generated from vessel wall imaging data obtained using the SPACE sequence in the depiction of stented arteries by comparing with three-dimensional time-of-flight magnetic resonance angiography and digital subtraction angiography.

METHODS

Our study group comprised 11 consecutive patients. For both three-dimensional time-of-flight magnetic resonance angiography and black-blood magnetic resonance angiography, the contrast ratio obtained from the stented artery and the normal artery proximal to the stent were calculated. And the depiction of stented arteries was visually evaluated. Additionally, the relative diameter index obtained from the stented artery and the normal artery proximal to the stent were calculated for three-dimensional time-of-flight magnetic resonance angiography, black-blood magnetic resonance angiography and digital subtraction angiography.

RESULTS

The contrast ratio of the stented artery was significantly lower than that of the normal artery on three-dimensional time-of-flight magnetic resonance angiography, but no significant difference was seen using black-blood magnetic resonance angiography. Regarding both the diameter index and the visual assessment score, black-blood magnetic resonance angiography was significantly better than three-dimensional time-of-flight magnetic resonance angiography. On black-blood magnetic resonance angiography, the diameter index was equal to that of digital subtraction angiography, and the flow signal was homogeneous and continuous in most the cases.

Differential Diagnosis of Intraplaque Hemorrhage and Dissection on High-Resolution MR Imaging in Patients with Focal High Signal of the Vertebrobasilar Artery on TOF Imaging

PURPOSE

Intraplaque hemorrhage (IPH) and dissection in the vertebrobasilar artery (VBA) on time of flight (TOF) source imaging are seen as focal eccentric high-signal intensity. The purpose of this study is to identify IPH and dissection in the VBA using high-resolution magnetic resonance imaging (HR-MRI).

METHODS

A total of 78 patients (VBA IPH: 55; dissection: 23) with focal high-signal intensity in the VBA on simultaneous non-contrast angiography and intraplaque hemorrhage (SNAP) of HR-MRI were included in this study. The focal high-signal intensity in the VBA on SNAP was defined as >200% than that of the adjacent muscle. We analyzed the signal intensity ratio (area of focal high signal intensity area/lumen) on TOF imaging and black blood (BB) T2-weighted imaging.

RESULTS

The VBA IPH group was older than the dissection group and had more hypertension. Signal intensity of a false lumen in patients with dissection on TOF imaging was significantly higher than that of VBA IPH (p < 0.001). The signal intensity ratio between lumen and lesion on TOF imaging was significantly higher in the dissection group (p < 0.001). The signal intensity of a false lumen in patients with dissection on BB T2-weighted imaging was significantly lower than that of VBA IPH (p < 0.001). The signal intensity ratio between lumen and lesion on BB T2-weighted imaging was significantly higher in the VBA IPH group (p < 0.001).

CONCLUSIONS

TOF imaging and BB T2-weighted imaging on HR-MRI in patients with focal eccentric high-signal intensity on TOF imaging can distinguish between VBA IPH and dissection.

Quantitative and Qualitative Analysis of Atherosclerotic Stenosis in the Middle Cerebral Artery Using High-Resolution Magnetic Resonance Imaging

PURPOSE

We analyzed and compared the imaging characteristics of the vessel wall of the middle cerebral artery (MCA) in symptomatic and asymptomatic patients using a 3.0-T high-resolution magnetic resonance imaging (HR-MRI) protocol, including a 3-dimensional T1-sampling perfection with application-optimized contrasts using different flip angle evolutions sequence.

METHODS

Fifty-three patients with atherosclerotic stenosis of the MCA underwent 3.0-T HR-MRI examinations. The characteristics of atherosclerotic plaques in 53 patients (28 symptomatic, 25 asymptomatic) were analyzed, including plaque distribution and signal intensity. Plaque burden (PB), stenosis degree, and the remodeling index were measured and compared between symptomatic and asymptomatic patients.

RESULTS

The PB of the symptomatic group was significantly higher than that of the asymptomatic group (P = .006), and moderate-severe stenosis was more common (P = .01). The remodeling index of the symptomatic group was also lower (P = .015) and negative remodeling (NR) was more common (P = .043). Binary logistic regression analysis showed that stenosis degree was a risk factor in symptomatic patients (odds ratio = 135, P = .023).

CONCLUSION

There is a trend that some characteristics of plaques and vessels, including the moderate-severe stenosis, larger PB, and NR, were observed more frequently among patients with symptomatic atherosclerotic stenosis of the MCA than among asymptomatic patients.

Effect of vasa vasorum in cerebrovascular compensation: 2 case reports

Intracranial vasa vasorum (VV) are rare and develop predominantly in the proximal segments of the internal carotid artery (ICA) and vertebral artery (VA). The typical appearance of intracranial VV has not yet been reported in clinical practice. Although VV in the ICA have been found to re-institute the collateral flow, bypassing the obstructive segment, far less attention has been paid to the manner in which VV can connect the two ends of the obstructive segment through the plaque. In this study, we present two cases and discuss the positive effects of VV. In our first case, a patient with basilar artery (BA) occlusion and multiple infarcts in the posterior circulation territory received endovascular treatment. Digital subtraction angiography (DSA) showed the existence of VV, which originated from the proximal BA lumen, penetrated through the vessel wall, bypassed the obstructive segment, re-penetrated through the vessel wall, and reconnected to the distal BA lumen. Balloon angioplasty was performed, specifically avoiding the path of the VV, then the VV had disappeared in follow-up angiography. In our second case, a patient who had been diagnosed with occlusion in the initial segment of the left ICA two years ago suffered a stroke. DSA revealed that the VV collaterals penetrated directly through the plaque of obstructive site and reconnected to the distal vessel lumen, which caused low hemodynamic compensation. Angioplasty was performed directly following the VV path, then follow-up angiography showed the VV had disappeared. Arterial occlusion, including in the intracranial and extracranial artery, could trigger the occurrence of VV, which can improve downstream perfusion. VV also could play a role of signal light in endovascular treatment.

Clinical characteristics of perivascular space and brain CT perfusion in stroke-free patients with intracranial and extracranial atherosclerosis of different extents

Background

This study aimed to investigate the clinical characteristics of perivascular space (PVS) and cerebral blood flow (CBF) in stroke-free patients with intracranial and extracranial atherosclerosis of different extents.

Methods

Two hundred and twenty-two patients received carotid artery ultrasonography, magnetic resonance imaging (MRI), cranial computed tomography angiography (CTA) and computed tomography perfusion (CTP). PVS was scored. The extents of intracranial and extracranial arteriosclerosis were evaluated based on the scores of intracranial and extracranial arteriosclerosis. CTP was done to determine the CBF in the region of interest (ROI). The risk factors of vascular disease were assessed in patients with and without PVS. The relationship between PVS and CBF was evaluated among patients with different scores of intracranial and extracranial atherosclerosis.

Results

The incidences of intracranial atherosclerosis and extracranial carotid plaque were higher in PVS patients. Subjects with intracranial and/or extracranial arteriosclerosis also had a higher incidence of PVS as compared to controls. The score of intracranial and/or extracranial arteriosclerosis was positively related to the score of basal ganglia PVS. Patients with intracranial and/or extracranial arteriosclerosis had lower CBF as compared to controls. The CBF was negatively associated with the intracranial and/or extracranial arteriosclerosis and the PVS score.

Conclusions

The incidence of PVS in patients with intracranial and extracranial arteriosclerosis is higher than in patients without arteriosclerosis. The extent of intracranial and extracranial atherosclerosis is related to PVS, especially the basal ganglia PVS. The decreased CBF may be associated with the occurrence of PVS.

Intracranial artery stenosis magnetic resonance imaging aetiology and progression study: Rationale and design

BACKGROUND

It has been shown that intracranial artery stenosis (ICAS) plays a key role in Chinese ischemic stroke or transient ischemic attack (TIA) patients. Many vascular diseases can lead to ICAS, such as atherosclerosis, dissection, vasculitis, moyamoya disease, and reversible cerebral vasoconstriction syndrome (RCVS). In addition, progression of intracranial atherosclerotic disease (ICAD) will increase the risk of ischemic cerebrovascular events. The ICASMAP study primarily aims to determine the etiology and disease distribution of ICAS using noninvasive magnetic resonance (MR) imaging and evaluate the rate for progression of ICAD in symptomatic population.

METHODS

The ICASMAP study is a prospective, observational, and multicenter study by recruiting 300 subjects (18-80 years old) with recent stroke or TIA (within 2 weeks after onset of symptoms) in China. All the subjects will undergo MR imaging examination including brain and intracranial artery MR imaging at baseline. In addition, the clinical risk factors will be collected and blood biomarkers will be tested. A subgroup of more than 200 subjects who were diagnosed with ICAD according to baseline MR imaging will be followed up for 2 years. During the follow-up study, MR imaging examination will be performed at 12 and 24 months. The primary end point is presence of progression of intracranial artery atherosclerotic plaques.

CONCLUSIONS

The ICASMAP study investigates the etiology of ICAS and progression of ICAD in Chinese stroke patients and may help to improve the precise diagnosis and intervention of ICAS and stroke prevention.

Predictors of Stroke Events in Patients with Transient Ischemic Attack Attributable to Intracranial Stenotic Lesions

Objective The purpose of this study was to identify the predictors of subsequent ischemic stroke events in patients with transient ischemic attack (TIA) attributable to intracranial arterial occlusive lesions. Methods The study population included 82 patients (55 men; mean age, 69.3±12.1 years) with TIA caused by intracranial arterial occlusive lesions who were admitted to our stroke care unit within 48 h of the onset of a TIA between April 2008 and November 2015. TIA was diagnosed if focal neurological symptoms ascribable to a vascular etiology lasted less than 24 h, irrespective of the presence of ischemic insults on imaging. The primary endpoint was an ischemic stroke event within 90 days of the onset of a TIA. Results The 90-day risk of ischemic stroke after the onset of a TIA was 14.6% [95% confidence interval (CI): 8.6-23.9%]. Cox proportional hazards multivariate analyses revealed that diffusion-weighted imaging (DWI) positivity [hazard ratio (HR), 8.73; 95%CI, 2.20-41.59; p=0.002], prior ischemic stroke (HR, 4.03; 95%CI, 1.07-15.99; p=0.040), and a high serum level of alkaline phosphatase (ALP) on admission (HR, 1.15; 95%CI, 1.05-1.26; p=0.002, for every +10 U/L) were significant independent predictors of ischemic stroke within 90 days after the onset of a TIA. Conclusion Our results suggested that patients with a TIA attributable to intracranial artery disease who showed DWI lesions, prior ischemic stroke, or high serum levels of ALP on admission were at high risk of subsequent ischemic stroke events.

Development of a quantitative intracranial vascular features extraction tool on 3D MRA using semiautomated open-curve active contour vessel tracing

PURPOSE

To develop a quantitative intracranial artery measurement technique to extract comprehensive artery features from time-of-flight MR angiography (MRA).

METHODS

By semiautomatically tracing arteries based on an open-curve active contour model in a graphical user interface, 12 basic morphometric features and 16 basic intensity features for each artery were identified. Arteries were then classified as one of 24 types using prediction from a probability model. Based on the anatomical structures, features were integrated within 34 vascular groups for regional features of vascular trees. Eight 3D MRA acquisitions with intracranial atherosclerosis were assessed to validate this technique.

RESULTS

Arterial tracings were validated by an experienced neuroradiologist who checked agreement at bifurcation and stenosis locations. This technique achieved 94% sensitivity and 85% positive predictive values (PPV) for bifurcations, and 85% sensitivity and PPV for stenosis. Up to 1,456 features, such as length, volume, and averaged signal intensity for each artery, as well as vascular group in each of the MRA images, could be extracted to comprehensively reflect characteristics, distribution, and connectivity of arteries. Length for the M1 segment of the middle cerebral artery extracted by this technique was compared with reviewer-measured results, and the intraclass correlation coefficient was 0.97.

CONCLUSION

A semiautomated quantitative method to trace, label, and measure intracranial arteries from 3D-MRA was developed and validated. This technique can be used to facilitate quantitative intracranial vascular research, such as studying cerebrovascular adaptation to aging and disease conditions. Magn Reson Med 79:3229-3238, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

Evaluation of 3D multi-contrast joint intra- and extracranial vessel wall cardiovascular magnetic resonance

BACKGROUND

Multi-contrast vessel wall cardiovascular magnetic resonance (CMR) has demonstrated its capability for atherosclerotic plaque morphology measurement and component characterization in different vasculatures. However, limited coverage and partial volume effect with conventional two-dimensional (2D) techniques might cause lesion underestimation. The aim of this work is to evaluate the performance in a) blood suppression and b) vessel wall delineation of three-dimensional (3D) multi-contrast joint intra- and extracranial vessel wall imaging at 3T.

METHODS

Three multi-contrast 3D black blood (BB) sequences with T1, T2 and heavy T1 weighting and a custom designed 36-channel neurovascular coil covering the entire intra- and extracranial vasculature have been used and investigated in this study. Two healthy subjects were recruited for sequence parameter optimization and twenty-five patients were consecutively scanned for image quality and blood suppression assessment. Qualitative image scores of vessel wall delineation as well as quantitative Signal-to-Noise Ratio (SNR) and Contrast-to-Noise Ratio (CNR) were evaluated at five typical locations ranging from common carotid arteries to middle cerebral arteries.

RESULTS

The 3D multi-contrast images acquired within 15mins allowed the vessel wall visualization with 0.8 mm isotropic spatial resolution covering intra- and extracranial segments. Quantitative wall and lumen SNR measurements for each sequence showed effective blood suppression at all selected locations (P < 0.0001). Although the wall-lumen CNR varied across measured locations, each sequence provided good or adequate image quality in both intra- and extracranial segments.

CONCLUSIONS

The proposed 3D multi-contrast vessel wall technique provides isotropic resolution and time efficient solution for joint intra- and extracranial vessel wall CMR.