High-resolution MR imaging of the cervical arterial wall: what the radiologist needs to know

Clinical Application of Dark-blood Imaging in Head and Neck CT Angiography: Effect on Image Quality and Plaque Visibility

RATIONALE AND OBJECTIVES

The aim of this study was to explore the potential of a newly developed dark-blood imaging technique to improve image quality and plaque visibility in head and neck computed tomography (CT) angiography.

MATERIALS AND METHODS

Patients who underwent triphasic head and neck CT angiography scans from August 2021 to March 2023 were retrospectively enrolled (mean age 67.23 ± 10.81 [SD] years, range 43-85 years, 64.7% male). The CT protocol consists of pre-contrast, arterial and delayed phases. Dark-blood images were postprocessed with the contrast-enhancement boost (CE-boost) technique. The quantitative assessment involved evaluating the CT value, image noise, contrast-to-noise ratio (CNR), and signal-to-noise ratio (SNR) of calcified plaque and non-calcified plaque. The plaque CNR relative to the vessel lumen (CNRplaque-lumen), vessel wall (CNRplaque-wall), and adjacent muscle (CNRplaque-muscle) was respectively calculated. Two experienced radiologists independently evaluated the CT images (5, best; 1, worst) by four characteristics including calcified plaque visibility, non-calcified plaque visibility, diagnostic confidence, and overall image quality. Inter-rater variability was also evaluated. The artery stenosis rate and plaque burden on dark-blood images were measured and compared with arterial phases. The intraclass correlation coefficient (ICC) was used for consistency analysis. The diagnostic accuracy of dark-blood images for the stenosis rate was evaluated by the area under the curve (AUC).

RESULTS

A total of 43 patients with 54 calcified plaques and 34 non-calcified plaques were assessed in this study. When compared with pre-contrast and delayed phase, dark-blood images yielded significantly higher CNRplaque-lumen and CNRplaque-muscle of calcified (219.79 ± 159.20 and 181.23 ± 112.12, respectively) and non-calcified (30.30 ± 29.11 and 6.28 ± 4.75, respectively) plaques (all p < 0.001). Calcified plaque SNR of dark-blood showed equal or slightly lower than other phases (p > 0.05 or p = 0.02). A major increase was observed in the non-calcified plaque SNR of dark-blood compared to the arterial phase (5.56 ± 3.71 vs. 4.23 ± 3.56, p = 0.02), although there were no apparent differences compared to pre-contrast and delayed phases (p > 0.05). In subjective analyzes, the calcified plaque visibility (4.99 ± 0.07), non-calcified plaque visibility (4.62 ± 0.48), overall image quality (4.81 ± 0.34), and diagnostic confidence (4.74 ± 0.36) in dark-blood images dominated the highest scores (p < 0.001). The subjective scores of radiologists exhibited good consistency (all kappa value>0.7). The dark-blood image and the arterial phase image exhibited good consistency in identifying the stenosis rate (p < 0.001). In the evaluation of plaque burden, the interobserver agreement for dark-blood images was higher compared to arterial phase images (ICC = 0.870 vs. 0.729).

CONCLUSIONS

Compared to conventional triphasic head and neck CT angiography, the CE-boost derived dark-blood imaging demonstrated a significant improvement in image quality and visibility for both calcified and non-calcified plaque assessment.

The Role of High-Resolution Magnetic Resonance Imaging in Cerebrovascular Disease: A Narrative Review

High-resolution magnetic resonance imaging (HRMRI) is the most important and popular vessel wall imaging technique for the direct assessment of vessel wall and cerebral arterial disease. It can identify the cause of stroke in high-risk plaques and differentiate the diagnosis of head and carotid artery dissection, including inflammation, Moya Moya disease, cerebral aneurysm, vasospasm after subarachnoid hemorrhage, reversible cerebral vasoconstriction syndrome, blunt cerebrovascular injury, cerebral arteriovenous malformations, and other stenosis or occlusion conditions. Through noninvasive visualization of the vessel wall in vitro, quantified assessment of luminal stenosis and pathological features of the vessel wall can provide clinicians with further disease information. In this report, technical considerations of HRMRI are discussed, and current clinical applications of HRMRI are reviewed.

The carotid web: Current research status and imaging features

The carotid web is commonly found in the carotid bulb or the beginning of the internal carotid artery. It presents as a thin layer of proliferative intimal tissue originating from the arterial wall and extending into the vessel lumen. A large body of research has proven that the carotid web is a risk factor for ischemic stroke. This review summarizes the current research status of the carotid web and focuses on its imaging presentation.

Differentiation of Cerebral Dissecting Aneurysm from Hemorrhagic Saccular Aneurysm by Machine-Learning Based on Vessel Wall MRI: A Multicenter Study

The differential diagnosis of a cerebral dissecting aneurysm (DA) and a hemorrhagic saccular aneurysm (SA) often depends on the intraoperative findings; thus, improved non-invasive imaging diagnosis before surgery is essential to distinguish between these two aneurysms, in order to provide the correct formulation of surgical procedure. We aimed to build a radiomic model based on high-resolution vessel wall magnetic resonance imaging (VW-MRI) and a machine-learning algorithm. In total, 851 radiomic features from 146 cases were analyzed retrospectively, and the ElasticNet algorithm was used to establish the radiomic model in a training set of 77 cases. A clinico-radiological model using clinical features and MRI features was also built. Then an integrated model was built by combining the radiomic model and clinico-radiological model. The area under the ROC curve (AUC) was used to quantify the performance of models. The models were evaluated using leave-one-out cross-validation in a training set, and further validated in an external test set of 69 cases. The diagnostic performance of experienced radiologists was also assessed for comparison. Eight features were used to establish the radiomic model, and the radiomic model performs better (AUC = 0.831) than the clinico-radiological model (AUC = 0.717), integrated model (AUC = 0.813), and even experienced radiologists (AUC = 0.801). Therefore, a radiomic model based on VW-MRI can reliably be used to distinguish DA and hemorrhagic SA, and, thus, be widely applied in clinical practice.

A Spontaneous Extracranial Internal Carotid Artery Dissection with Autosomal Dominant Polycystic Kidney Disease: A Case Report and Literature Review

Background and Objectives: Non-cystic manifestation of autosomal dominant polycystic kidney disease (ADPKD) is an important risk factor for cerebral aneurysms. In this report, we describe a rare spontaneous internal carotid artery (ICA) dissection in a patient with ADPKD. Observations: A 38-year-old woman with a history of ADPKD and acute myocardial infarction due to coronary artery dissection experienced severe spontaneous pain on the left side of her neck. Magnetic resonance imaging (MRI) revealed a severe left ICA stenosis localized at its origin. Carotid plaque MRI showed that the stenotic lesion was due to a subacute intramural hematoma. Close follow-up by an imaging study was performed under the diagnosis of spontaneous extracranial ICA dissection, and spontaneous regression of the intramural hematoma was observed uneventfully. Conclusions: When patients with a history of ADPKD present with severe neck pain, it is crucial to consider the possibility of a spontaneous ICA dissection. A carotid plaque MRI is beneficial in the differential diagnosis. Conservative management may benefit patients without ischemic symptoms.

Evaluating intracranial artery dissection by using three-dimensional simultaneous non-contrast angiography and intra-plaque hemorrhage high-resolution magnetic resonance imaging: a retrospective study

BACKGROUND

There was no previous report on the three-dimensional simultaneous non-contrast angiography and intra-plaque hemorrhage (3D-SNAP) magnetic resonance imaging (MRI) sequence to diagnose intracranial artery dissection (IAD).

PURPOSE

To improve the diagnostic accuracy and guide the clinical treatment for IAD by elucidating its pathological features using 3D-SNAP MRI.

MATERIAL AND METHODS

From January 2015 to September 2018, 113 patients with suspected IAD were analyzed. They were divided into IAD and non-IAD groups according to the spontaneous coronary artery dissection (SCAD) criteria. All patients underwent 3D-SNAP, 3D-TOF, T2W imaging, 3D-PD, 3D-T1W-VISTA, and 3D-T1WCE) using 3.0-T MRI; clinical data were collected. The IAD imaging findings (intramural hematoma, double lumen, intimal flap, aneurysmal dilatation, stenosis, or occlusion) in every sequence were analyzed. Receiver operating characteristic (ROC) curve analysis was used to evaluate the diagnostic efficiency of each sequence.

RESULTS

There was a significant difference in the probability of intramural hematoma, relative signal intensity of intramural hematoma, double lumen, stenosis, or occlusion signs on 3D-TOF, T2W, 3D-PD, 3D-T1W-VISTA, 3D-SNAP, and 3D-T1WCE sequences (P<0.05). The 3D-SNAP and 3D-T1WCE sequences were most sensitive for diagnosing intramural hematoma and displaying double-lumen signs, respectively. The diagnostic efficiency of the 3D-SNAP sequence combined with 3D-T1WCE was the highest (area under the curve [AUC] 0.966). The AUC value of the 3D-SNAP sequence (AUC 0.897) was slightly inferior to that of 3D-T1W enhancement (AUC 0.903).

CONCLUSION

3D-SNAP MRI is a non-invasive and effective method and had the greatest potential among those methods tested for improving the diagnostic accuracy for IAD.

Treatment of basilar artery stenosis with an Apollo balloon-expandable stent: a single-centre experience with 61 consecutive cases

Stent placement for basilar artery (BA) stenosis remains a technical and clinical challenge. This retrospective study introduces the experience with the Apollo balloon-expandable stent (BES) for patients with symptomatic BA stenosis in a single centre in China. Sixty one patients who had undergone intervention for severe symptomatic BA stenosis between May 2012 and September 2018 were enrolled in this study. All patients underwent angioplasty and stenting with an Apollo BES and were followed-up continuously. The technical success rate was 100%. During the procedure, there was no vessel rupture or dissection. Two patients died due to perforator occlusion. One patient developed vasospasm with no symptoms. The rate of complications during the procedure was 4.91% (3/61). BA stent-related stroke or death rates were 4.9% at 30 days (3/61), 6.6% at 3 months (4/61), and 6.6% (4/61) at 6 months. One patient had stent occlusion at 6 months with no symptoms. Restenosis was found in five patients with degrees of restenosis greater than ≥ 50% without any symptoms. In this study, the Apollo BES appeared to be feasible for BA stenosis. Our experience may be valuable for reducing the number of complications. However, further study is needed.

Characteristics of Symptomatic Basilar Artery Stenosis Using High-Resolution Magnetic Resonance Imaging in Ischemic Stroke Patients

Aim: Arterial narrowing associated with the progression of atherosclerosis leads to serious conditions such as stroke, coronary artery disease, or even death. High-resolution magnetic resonance imaging (HR-MRI) is better for detecting arterial wall status and discriminating tissue characteristics than conventional imaging. We used HR-MRI to investigate the frequency of patients with basilar artery (BA) stenosis observed distinctively on routine angiography and identify the clinical features associated with this imaging. We analyzed the nature of the vessel wall causing the basal artery stenosis by HR-MRI, and related clinical factors.

Methods: Patients with BA stenosis underwent HR-MRI. The association between atherosclerosis (with or without intraplaque hemorrhage [IPH]) and dissection was analyzed. High signal intensity within a BA plaque on magnetization-prepared rapid acquisition with gradient echo was defined as an area with a signal intensity ＞200% that of the adjacent muscle.

Results: Fifteen patients were diagnosed with BA dissection on HR-MRI. IPH was identified in 14 patients. Patients with BA plaque with IPH were older and had higher prevalence of hypertension and hyperlipidemia than the other patients. The frequencies of alcohol drinking and number of current smokers were higher in the dissection group than in the other groups. Hyperlipidemia was identified as an influencing factor for IPH development in atherosclerotic plaque. Young age was identified as the influencing factor for the occurrence of BA dissection.

Conclusions: The etiology of stenosis or occlusion was unclear until the development of HR-MRI. With HR-MRI, stroke etiology is better understood, and factors affecting each etiology can be identified. Further studies that clarify the etiology of posterior circulation stroke are required.

One-step evaluation of intraplaque hemorrhage in the carotid artery and vertebrobasilar artery using simultaneous non-contrast angiography and intraplaque hemorrhage

PURPOSE

To investigate the one-step detection of intraplaque hemorrhage (IPH) in the carotid artery (CA) and vertebrobasilar artery (VBA) using simultaneous non-contrast angiography and intraplaque hemorrhage (SNAP).

METHODS

From January 2019 to March 2020, 1820 consecutive patients who visited our emergency room for evaluation of neurologic symptoms underwent brain MR imaging, including the SNAP sequence. SNAP imaging examined the coronal section from the CA to the VBA. IPH was defined as plaque in the CA and VBA with 200 % higher signal intensity on SNAP than in adjacent muscle in at least two consecutive slices.

RESULTS

Of these patients, 360 (19.8 %) had carotid plaque (both sides = 141, 39.2 %; single side = 219, 61.8 %). Of patients with carotid plaque, 185 (51.4 %) had IPH. Of 141 patients with plaques on both sides, 35 (24.8 %) had bilateral IPH. In total, 73 (4.0 %) patients had VBA IPH (30 with carotid plaque, 43 without carotid plaque). In addition, 18 (1.0 %) patients had carotid IPH and VBA IPH. Maximal wall thickness was significantly higher in the carotid IPH groups (4.5 ± 0.1 vs. 4.1 ± 0.1, p = 0.009). Prevalence of high grade stenosis (>70 %) was significantly higher in the carotid IPH group (17.5 % vs. 6.2 %, p < 0.001).

CONCLUSIONS

SNAP imaging can be evaluated with a one-step examination of CA and VBA IPH.

The role of CE-MRA of the supraortic vessels in the detection of associated intracranial pathology

BACKGROUND

Contrast-enhanced magnetic resonance angiography (CE-MRA) has become a very popular imaging technique in the evaluation of the extracranial vessels pathology, while it is not commonly used to rule out intracranial vascular pathology. On the contrary, 3D time of flight MRA (TOF-MRA) has a solid role in the study of intracranial arterial vessels disease.

MATERIALS AND METHODS

One hundred and eight patients were consecutively included in the study. All patients were submitted to a 3 Tesla 3D CE-MRA imaging to rule out extracranial vessels pathology. A comparison was made with a 3D-TOF sequence acquired at the same time in the assessment of intracranial vessels diseases such as steno-occlusion, dissection, and aneurysms.

RESULTS

With regard to steno-occlusive disease, Spearman's rank correlation coefficient was of 0.56 for stenosis detection and of 0.57 for occlusive disease detection. The two techniques shared similar results in the evaluation of anterior circulation, while 3D-TOF found higher grades of stenosis for posterior circulation. With regard to dissection, Spearman's rank correlation coefficient was of 0.7. 3D-TOF depicted more intramural hematoma (Spearman's rank = 0.46), while CE-MRA showed more pseudo-aneurysms (Spearman's rank = 0.56). Both the technique equally evaluated the presence of intracranial aneurysms (Spearman's rank = 1).

CONCLUSION

CE-MRA can be considered a reliable tool to rule out intracranial pathology associated to supraortic steno-occlusive disease, also allowing time reduction. In the suspicion of dissection a T1-weighted sequence has to be added to detect the presence of a subacute vessel wall hematoma.

Radiomic Model for Distinguishing Dissecting Aneurysms from Complicated Saccular Aneurysms on high-Resolution Magnetic Resonance Imaging

OBJECTIVE

To build radiomic model in differentiating dissecting aneurysm (DA) from complicated saccular aneurysm (SA) based on high-resolution magnetic resonance imaging (HR-MRI) through machine-learning algorithm.

METHODS

Overall, 851 radiomic features from 77 cases were retrospectively analyzed, and the ElasticNet algorithm was used to build the radiomic model. A clinico-radiological model using clinical features and conventional MRI findings was also built. An integrated model was then built by incorporating the radiomic model and clinico-radiological model. The diagnostic abilities of these models were evaluated using leave one out cross validation and quantified using the receiver operating characteristic (ROC) analysis. The diagnostic performance of radiologists was also evaluated for comparison.

RESULTS

Five features were used to form the radiomic model, which yielded an area under the ROC curve (AUC) of 0.912 (95 % CI 0.846-0.976), sensitivity of 0.852, and specificity of 0.861. The radiomic model achieved a better diagnostic performance than the clinico-radiological model (AUC=0.743, 95 % CI 0.623-0.862), integrated model (AUC=0.888, 95 % CI 0.811-0.965), and even many radiologists.

CONCLUSION

Radiomic features derived from HR-MRI can reliably be used to build a radiomic model for effectively differentiating between DA and complicated SA, and it can provide an objective basis for the selection of clinical treatment plan.

Association between Pregnancy and Cervical Artery Dissection

OBJECTIVE

We wanted to determine whether pregnancy is associated with cervical artery dissection.

METHODS

We performed a case-control study using claims data from all nonfederal emergency departments and acute care hospitals in New York and Florida between 2005 and 2015. Cases were women 12-42 years of age hospitalized with cervical artery dissection, defined using validated diagnosis codes for carotid/vertebral artery dissection. Controls were women 12-42 years of age with a primary diagnosis of renal colic. Cases and controls were matched 1:1 on age, race, insurance, income, state, and visit year. The exposure variable was pregnancy, defined as labor and delivery within 90 days before or 6 months after the index visit. Logistic regression was used to compare the odds of pregnancy between cases and controls. We performed a secondary cohort-crossover study comparing the risk of cervical artery dissection during pregnancy versus the same time period 1 year later.

RESULTS

Pregnancy was twice as common among 826 women with cervical artery dissection compared with the 826 matched controls with renal colic (odds ratio, 2.5; 95% confidence interval [CI], 1.3-4.7). In our secondary analysis, pregnancy was associated with a higher risk of cervical artery dissection (incidence rate ratio [IRR], 2.2; 95% CI, 1.3-3.5), with the heightened risk limited to the postpartum period (IRR, 5.5; 95% CI, 2.6-11.7).

INTERPRETATION

Pregnancy, specifically the postpartum period, was associated with hospitalization for cervical artery dissection. Although these findings might in part reflect ascertainment bias, our results suggest that arterial dissection is one mechanism by which pregnancy can lead to stroke. ANN NEUROL 2020;88:596-602.

Cervical Artery Dissections with and without stroke, risk factors and prognosis: a Chilean prospective cohort

We aimed to characterize spontaneous cervical artery dissection (CeAD) patients with and without stroke and describe risk factors for cerebrovascular complications in a Chilean prospective cohort.

METHODS

Consecutive CeAD patients admitted to a Chilean center confirmed by neuroimaging. Logistic regression was used.

RESULTS

168 patients were included, median follow-up time was 157 days. Stroke occurred in 49 (29.2%) cases, 4 (2%) patients died, all of whom had a stroke, and 10 (6%) presented CeAD recurrence. In univariate analyses, men (odds ratio [OR] 3.97, 95% confidence interval [CI] 1.97-8.00, P < 0.001), internal carotid artery CeAD (OR 2.82, 95% CI 1.38-5.78, P = 0.005) and vessel occlusion (OR 4.45, 95% CI 1.38-14.38, P = 0.035) increased stroke risk. Conversely, vertebral artery dissection (OR 0.35, 95% CI 0.16-0.74, P = 0.006) and longer symptom onset to admission (O-A) time (OR 0.79, 95% CI 0.70-0.90, P < 0.001) were associated to decreased stroke risk. After multivariate analysis, men (OR 2.88, 95% CI 1.32-6.27, P = 0.008) and O-A time (OR 0.80, 95% CI 0.69-0.92, P = 0.002) remained independently associated with stroke.

CONCLUSION

CeAD presented commonly as a non-stroke entity, with favorable prognosis. Albeit to a higher frequency of CeAD in women, stroke occurred predominantly in men, who were admitted earlier.

Intramural Hematoma Shape and Acute Cerebral Infarction in Intracranial Artery Dissection: A High-Resolution Magnetic Resonance Imaging Study

BACKGROUND

Intracranial artery dissection (IAD) is gaining recognition as an important cause of stroke, but limited information is available about the morphology of the dissection. This study aimed to investigate the relationship between acute cerebral infarctions and the shape of hematoma in patients with IADs using high-resolution magnetic resonance imaging (HRMRI).

METHODS

We enrolled consecutive patients who presented with vascular headaches, transient ischemic attacks, or ischemic strokes with acute IAD confirmed by HRMRI using key pathognomonic radiological findings of IAD, including intimal flap, intramural hematoma (IMH), and double lumen. All patients were enrolled and HRMRI was performed, both within 7 days of symptom onset. All patients with acute ischemic infarction within 7 days were enrolled. Patients were divided into 2 groups: those with a proximal dominant intramural hematoma (PIMH) and those with a distal dominant intramural hematoma (DIMH). A PIMH was defined as when the volume of the hematoma in the proximal region was greater than that in the distal region, and a DIMH was defined as when the distal region was greater than that in the proximal region. Clinical and radiological characteristics between the 2 groups were compared using univariable and multivariable logistic regression.

RESULTS

The mean age of the 42 participants was 52.6 ± 12.7 years, and 24 (57.1%) were male. Twenty-seven (64.3%) had a PIMH and 15 (35.7%) had a DIMH. Thirty-six (85.7%) showed a double lumen and 27 (64.3%) showed a dissecting flap. Acute infarction was observed in 31 (73.8%) patients. Patients with PIMHs showed a higher prevalence of cerebral infarction than those with DIMHs (96.3 vs. 33.3%; p < 0.001). Univariable (odds ratio [OR] 52.00; 95% confidence interval [CI] 5.386-502.082; p = 0.001) and multivariable (OR 65.43; 95% CI 5.20-822.92; p = 0.001) analyses showed that only dissection type was independently associated with the risk of cerebral infarction.

CONCLUSION

In patients with cerebral artery dissections, the shape of IMHs was independently associated with cerebral infarction. PIMHs may be more closely associated with cerebral infarctions than DIMHs.

Gadolinium Enhancement of the Aneurysm Wall in Extracranial Carotid Artery Aneurysms

BACKGROUND AND PURPOSE

The natural history and optimal treatment of extracranial carotid artery aneurysms are unknown. Gadolinium enhancement of the aneurysm wall may reflect aneurysm wall inflammation and instability. In this study, we investigated the feasibility of extracranial carotid artery aneurysm wall imaging and explored a potential relationship of aneurysm wall enhancement with aneurysm growth and the presence of (silent) brain infarcts and white matter lesions.

MATERIALS AND METHODS

Fourteen conservatively treated patients with 15 asymptomatic extracranial carotid artery aneurysms underwent gadolinium-enhanced 3T MR imaging at 2 time points with a 12-month interval. Primary outcome was growth of the aneurysm sac (≥2.0 mm); secondary outcomes were the presence of (silent) brain infarcts and white matter lesions at baseline and follow-up. MR images were reviewed by 2 independent observers, and inter- and intraobserver reproducibility was assessed.

RESULTS

Seven (50%) patients were men; the median age was 55 years (range, 40-69 years). Eleven extracranial carotid artery aneurysms (73%) were saccular (median size, 11 mm; range, 5.0-38.5 mm), and 4 were fusiform (median size, 21.5 mm; range, 10.0-40.0 mm). Eleven of 15 aneurysms (73%) exhibited gadolinium enhancement at baseline. Four aneurysms (27%) showed growth at follow-up imaging, 2 gadolinium-positive (+) and 2 gadolinium-negative (-) (P = .245). Three patients (21%) had ipsilateral brain infarcts at baseline; 1 of them showed a new silent brain infarct at follow-up imaging (gadolinium+). Nine patients (64%) showed bilateral white matter lesions at baseline. In 3 patients, increased white matter lesion severity was observed at follow-up (2 gadolinium+). All observations showed excellent inter- and intraobserver reproducibility.

CONCLUSIONS

In this explorative study, we demonstrated that extracranial carotid artery aneurysm wall imaging was feasible. Future well-powered studies are needed to investigate whether extracranial carotid artery aneurysm gadolinium enhancement predicts aneurysm growth and thromboembolic complications.

Evaluating cervical artery dissections in young adults: a comparison study between high-resolution MRI and CT angiography

To compare the diagnostic values of high-resolution magnetic resonance (HR-MRI) with computed tomographic angiography (CTA) in young adults with ischemic stroke due to cervical artery dissections. Totally 42 symptomatic patients were recruited in this study. All the 42 patients underwent both HR-MRI and CTA, including 28 patients with dissections confirmed by Digital Subtraction Angiography (DSA) and 4 patients with vertebral artery dissections diagnosed by follow-up. CTA and HR-MRI images were separately and blindly analyzed by two radiologists. The sensitivity, specificity, positive and negative predictive value of HR-MRI and CTA were calculated. The receiver operating characteristic (ROC) curves and AUC of each imaging modality were generated. A total of 20 carotid artery dissections, 12 vertebral artery dissections and 10 non-dissected cervical arteries were involved. The inter-observer concordance of HR-MRI and CTA was good (κ = 0.806 vs. 0.776). The sensitivity and specificity of HR-MRI and CTA on detecting the dissections were 87.5% vs. 62.5%, and 90.0% vs. 80.0%, respectively. Area under the ROC curve of HR-MRI [0.94 (95% CI 0.86-0.97)] was greater than that of CTA [0.87 (95% CI 0.71-1.0)]. Compared to CTA, HR-MRI is more sensitive and specific for the diagnosis of cervical artery dissections in high-risk symptomatic patients. This study supports the value of HR-MRI in non-invasive diagnosis of young adults with cervical artery dissections.

Craniocervical Arterial Dissection in Children: Pathophysiology and Management

BACKGROUND

Craniocervical arterial dissection is a commonly reported arteriopathy associated with stroke in children. It is characterized by a high stroke recurrence rate and variable outcomes. Here we review the pathophysiology, clinical presentation, and diagnostic neuroimaging approaches that are helpful in accurate diagnosis and follow-up of children with arterial dissection.

METHODS

MEDLINE searches (2000 to 2018) for articles that contained patients aged less than 18 years with craniocervical arterial dissection was performed, with the goal of analyzing their presenting features, pathophysiological mechanisms, and imaging characteristics and interventions.

RESULTS

Sixteen articles met the study criteria and reported 182 cases of craniocervical arterial dissection, 68% male, average age 8.6 years. Dissection was associated with head and neck trauma in 56% of the cases and frequently involved the posterior (61%) and extracranial locations (64%); the vertebral artery was the most commonly involved artery (60%). The most common clinical presentation was hemiparesis (80/160, 50%), followed by headache (64/164, 39%). Magnetic resonance imaging was the preferred neuroimaging method, followed by cerebral catheter angiography as a gold standard definitive neurovascular imaging modality when the initial vascular imaging revealed nondiagnostic findings.

CONCLUSIONS

The diagnosis of arterial dissection requires a high index of suspicion and consideration for detailed neurovascular imaging, including both the cranial and cervical regions. Neurovascular imaging challenges, especially visualization of arterial abnormalities, highlight the importance of appropriate and timely use of specific neurovascular imaging techniques. Magnetic resonance imaging appears to be the preferred neurovascular imaging modality in children with arterial dissection and may obviate the need for invasive cerebral catheter angiography.

Reproducibility of 3.0T High-Resolution Magnetic Resonance Imaging for the Identification and Quantification of Middle Cerebral Arterial Atherosclerotic Plaques

OBJECTIVE

To assess the reproducibility of 3.0T high-resolution magnetic resonance imaging for the identification and quantification of atherosclerotic plaques in the middle cerebral artery.

METHODS

Sixty-nine consecutive patients with ischemic stroke or asymptomatic stenosis (>30%) of the middle cerebral artery underwent 3.0T high-resolution magnetic resonance imaging examinations. Two independent investigators reviewed all images with 1 investigator re-evaluating all images 4 weeks later. Wall characteristics of the middle cerebral artery, including plaque surface morphology, plaque location, plaque components, and burden were identified and measured.

RESULTS

Intraobserver and interobserver agreement were all substantial in identifying plaque surface irregularity (k = 0.741, 0.555-0.897; k = 0.685, 0.490-0.843; respectively) and intraplaque hemorrhage (k = 0.654, 0.446-0.838; k = 0.605, 0.369-0.792; respectively). Intraobserver agreement was substantial (k = 0.654) and interobserver agreement was moderate (k = 0.553) for the identification of plaque fibrous caps. The total intraobserver and interobserver reproducibility was almost excellent for the identification of plaque position. With regards to vessel area measurement at the site of maximal lumen narrowing, intraobserver and interobserver reproducibility was excellent (intraclass correlation coefficient was 0.886 and 0.885, respectively) and moderate for lumen area at the site of maximal lumen narrowing (intraclass correlation coefficient was 0.695 and 0.558, respectively). In addition, intraobserver and interobserver reproducibility was excellent for vessel area and lumen area measurements at the reference sites.

CONCLUSIONS

The reproducibility of 3.0T high-resolution magnetic resonance imaging for the identification and quantification of artery wall characteristics was overall acceptable. However, the reliability for lumen area measurement at the maximum narrowing site and identification of the fibrous cap needs to be improved.

Imaging Spectrum of TIPIC Syndrome : Validation of a new Entity with Vessel Wall Imaging

PURPOSE

Acute neck pain can have non-vascular and vascular causes. Some patients present with distinct vascular and perivascular changes on imaging at the site of tenderness. This study aimed to evaluate the imaging findings of transient perivascular inflammation of the carotid artery (TIPIC) syndrome with an emphasis on vessel wall imaging using 3‑Tesla (3-T) high-resolution (HR) magnetic resonance imaging (MRI).

METHODS

Clinical data along with diagnostic and follow-up imaging of patients presenting to these hospitals with acute neck pain/tenderness and at least 1 imaging study using color Doppler ultrasound (CDU) and/or MRI including vessel wall imaging from September 2013 through September 2017 were retrospectively evaluated. A total of 15 patients with no other underlying cause of pain, findings meeting the imaging criteria for TIPIC syndrome and clinical recovery (spontaneous or with treatment) were included in the study.

RESULTS

The mean patient age was 43.2 years. With CDU and precontrast MRI, perivascular inflammation (PVI) of the involved artery segment was evident in all patients. Contrast enhancement of the adventitia and PVI were noted on postcontrast HR vessel wall MRI in all patients. Of the patients five had co-existing plaques at the site of tenderness. Follow-up imaging demonstrated pronounced regression or complete resolution of the findings.

CONCLUSION

Imaging is useful for the establishment of TIPIC syndrome diagnosis and to rule out other conditions. The use of CDU is usually sufficient for diagnosis and follow-up but in clinically doubtful and complicated cases, vessel wall imaging with HR-MRI is very valuable. Thorough knowledge of this entity among radiologists enables a prompt diagnosis, which accelerates the clinical management.

New developments in clinical ischemic stroke prevention and treatment and their imaging implications

Acute ischemic stroke results from blockage of a cerebral artery or impaired cerebral blood flow due to cervical or intracranial arterial stenosis. Ischemic stroke prevention seeks to minimize the risk of developing impaired cerebral perfusion by controlling vascular and cardiac disease risk factors. Similarly, ischemic stroke treatment aims to restore cerebral blood flow through recanalization of an occluded artery or dilation of a severely narrowed artery that supplies cerebral tissue. Stroke prevention and treatment are increasingly informed by imaging studies, and neurovascular and cerebral perfusion imaging has become essential in in guiding ischemic stroke prevention and treatment. Here we review the latest advances in ischemic stroke prevention and treatment with an emphasis on the neuroimaging principles emphasized in recent randomized trials. Future research directions that should be explored in ischemic stroke prevention and treatment are also discussed.

Magnetic resonance imaging of intracranial atherosclerosis: Comparison of ex vivo 3T MRI and histologic findings

PURPOSE

Imaging the lipid-rich necrotic core (LRNC) is very important when evaluating the response of lipid-lowering therapy. The purpose of this study was to assess ex vivo LRNC of intracranial atherosclerosis using 3T MRI.

MATERIALS AND METHODS

Thirty-one atherosclerotic lesions from 17 specimens were analyzed (basilar artery=15, middle cerebral artery=16) using 3T MRI. Specimens were not chemically processed for imaging studies. Reconstructed MRI was matched with histologic sections at corresponding locations.

RESULTS

The median plaque thickness of intracranial atherosclerosis was 0.6mm (0.4-2.0mm). All specimens had a LRNC on histologic findings. Three specimens had plaque calcification on histologic findings. LRNC of 30 specimens (96.8%) appeared as homogeneous isointensity/hypointensity on T1-weighted imaging and hypointensity on T2-weighted imaging compared with T1-weighted imaging.

CONCLUSIONS

All specimens with ex vivo intracranial atherosclerosis had LRNC. Intracranial atherosclerosis could be an indication for lipid-lowering therapy, similar to previous carotid MR studies.

Quantitative Analysis of Intracranial Vertebrobasilar Dissecting Aneurysm with Intramural Hematoma After Endovascular Treatment Using 3-T High-Resolution Magnetic Resonance Imaging

OBJECTIVE

Quantitative measurements of intracranial vessel walls are reliable in 3-T high-resolution magnetic resonance imaging (HR-MRI). However, few reports have assessed the arterial wall after endovascular treatment (EVT) by 3-T HR-MRI. This study aimed to quantitatively analyze vessel walls in vertebrobasilar artery dissecting aneurysms after EVT.

METHODS

From May 2012 to December 2015, a total of 21 patients with 21 intracranial vertebrobasilar dissecting aneurysms (VBDAs) were enrolled in this consecutive study. All the VBDAs were characterized by intramural hematomas (IMHs ≥5 mm) and treated with reconstructive EVT. Images of preoperative and follow-up 3-T HR-MRI were used to evaluate the arterial wall. The relative signal intensity (RSI) of IMHs was quantified on T1-weighted imaging (T1WI) and magnetization-prepared rapid acquisition gradient-echo (MPRAGE).

RESULTS

Angiographic follow-up was performed for a mean of 9.19 ± 3.22 months. According to angiographic results at follow-up, 21 patients were divided into 2 groups (progressive group, n = 6; stable group, n = 15). In the progressive group, RSI of IMHs was significantly increased on MPRAGE of follow-up 3-T HR-MRI compared with that before treatment (P < 0.05), and the difference was not significant on T1WI. However, in the stable group, RSI of IMHs was significantly reduced after treatment (P < 0.05).

CONCLUSIONS

Persistent high signal intensity of IMHs in VBDAs after reconstructive EVT may be associated with the progression of VBDAs. It may also indicate an unsteady state of the aneurysm, which suggests that reconstruction of the parent artery is not satisfactory.

Added Value of 3D Proton-Density Weighted Images in Diagnosis of Intracranial Arterial Dissection

Background

An early and reliable diagnosis of intracranial arterial dissection is important to reduce the risk of neurological complication. The purpose of this study was to assess the clinical usefulness of three-dimensional high-resolution MRI (3D-HR-MRI) including pre- and post-contrast T1-weighted volumetric isotropic turbo spin echo acquisition with improved motion-sensitized driven equilibrium preparation (3D-iMSDE-T1) and proton-density weighted image (3D-PD) in detecting dissection and to evaluate the added value of 3D-PD in diagnosing intracranial arterial dissection.

Methods

We retrospectively recruited patients who underwent 3D-HR-MRI with clinical suspicion of arterial dissection. Among them, we selected patients who were diagnosed with definite dissection according to the Spontaneous Cervicocephalic Arterial Dissections Study criteria. For each patient, the presence of intimal flap, intramural hematoma, and vessel dilatation were evaluated independently by two neuroradiologists on each sequence. Interobserver agreement was assessed.

Results

Seventeen patients (mean age: 41 ± 10 [SD] years; 13 men) were diagnosed with definite dissection. The intimal flaps were more frequently detected on 3D-PD (88.2%, 15/17) than on 3D-iMSDE-T1 (29.4%, 5/17), and post-contrast 3D-iMSDE-T1 (35.3%, 6/17; P = 0.006 and P = 0.004, respectively). No significant difference was found in the detection rate of intramural hematomas (59–71%) and vascular dilatations (47%) on each sequence. Interobserver agreement for detection of dissection findings showed almost perfect agreement (k = 0.84–1.00), except for detection of intimal flaps on pre-contrast 3D-iMSDE-T1 (k = 0.62). After addition of 3D-PD to pre- and post-contrast 3D-iMSDE-T1, more patients were diagnosed with definite dissection with the initial MRI (88.2% vs. 47.1%; P = 0.039).

Conclusions

The intimal flap might be better visualized on the 3D-PD sequence than the 3D-iMSDE-T1 sequences, allowing diagnosis of definite dissection without follow-up imaging.

Quantitative Analysis Using High-Resolution 3T MRI in Acute Intracranial Artery Dissection

BACKGROUND AND PURPOSE

Quantitative measurements, as well as qualitative characterizations, of the vessel walls of the small intracranial arteries became clinically available and reliable beyond the resolution limit of 1.5 T high-resolution magnetic resonance imaging (HR-MRI) with the development of 3 T HR-MRI. We present the quantitative dissection findings of spontaneous and unruptured acute intracranial artery dissection (SID) using 3 T HR-MRI and investigate the differences between each cerebral artery.

METHODS

Twenty-eight lesions (anterior cerebral artery = 6; middle cerebral artery = 4; vertebral artery = 18) from 26 patients (17 male and 9 female patients; mean age = 47 years; age range = 32-74 years) with presumptive diagnoses of SID were included. The diagnosis was determined based on the clinical features, findings on luminal angiography (such as digital subtraction angiography, computed tomography, or magnetic resonance angiography), and HR-MRI. HR-MRI was performed within one month from onset. The neuroimaging indices (maximal outer diameter and area, remodeling index and modified remodeling index, and wall thickness and wall area index) of aneurysmal dilatation and the signal intensities of the intramural hematomas were rated using HR-MRI. The results were compared between each cerebral artery.

RESULTS

The maximal outer diameter and area, remodeling index and modified remodeling index, and wall thickness index and length were significantly different between anterior and posterior circulation (P < .05). The mean relative signal intensities of the intramural hematoma showed consistent values, regardless of the cerebral arteries, without significant difference.

CONCLUSIONS

Neuroimaging indices of aneurysmal dilatation may be adjunctive indicators in the evaluation of SID.

Wall characteristics and mechanisms of ischaemic stroke in patients with atherosclerotic middle cerebral artery stenosis: a high-resolution MRI study

OBJECTIVE

To evaluate the characteristics of atherosclerotic middle cerebral artery (MCA) stenosis by high-resolution magnetic resonance imaging (HR-MRI) and determine the relationship between wall characteristics and infarction patterns.

METHODS

Thirty-six patients with acute ischaemic stroke due to MCA stenosis underwent diffusion-weighted magnetic resonance imaging (DWI) and HR MRI. Wall characteristics of MCA, including irregular surface, superior location, T2-hyperintense of plaques and positive remodelling (PR), were analysed. Characteristics of acute infarct on DWI were categorised according to the number (single or multiple infarcts) and the pattern of cerebral infarcts (cortical, border zone or perforating artery territory infarcts). The relationship between wall characteristics and infarction patterns was evaluated.

RESULTS

PR was observed in 20 patients, irregular surface plaque in 18 patients, superior location of plaques in 14 patients and T2-hyperintense foci in 13 patients. Seventeen patients had multiple acute cerebral infarcts and 13 showed single acute cerebral infarcts. Border zone infarcts were the most common (76.5%) among multiple acute infarcts. Penetrating artery infarcts (PAI) accounted for 76.9% of all single infarcts. Multiple infarcts were more frequently observed in patients with PR (P =  0.007) or plaque surface irregularity (P =  0.035). Single infarcts, especially PAI, were more prevalent in patients with superior plaque (P =  0.030). No statistically significant differences were observed between multiple and single infarcts in patients with T2-hyperintense lesions (P = 0.638).

CONCLUSIONS

PR or irregular surface plaques were associated with artery-to-artery embolism. Superior location of plaques was associated with PAI. HR-MRI provides insights into intracranial atherosclerosis in vivo, predictive of infarction patterns.

Vessel Wall Imaging of the Intracranial and Cervical Carotid Arteries

Vessel wall imaging can depict the morphologies of atherosclerotic plaques, arterial walls, and surrounding structures in the intracranial and cervical carotid arteries beyond the simple luminal changes that can be observed with traditional luminal evaluation. Differentiating vulnerable from stable plaques and characterizing atherosclerotic plaques are vital parts of the early diagnosis, prevention, and treatment of stroke and the neurological adverse effects of atherosclerosis. Various techniques for vessel wall imaging have been developed and introduced to differentiate and analyze atherosclerotic plaques in the cervical carotid artery. High-resolution magnetic resonance imaging (HR-MRI) is the most important and popular vessel wall imaging technique for directly evaluating the vascular wall and intracranial artery disease. Intracranial artery atherosclerosis, dissection, moyamoya disease, vasculitis, and reversible cerebral vasoconstriction syndrome can also be diagnosed and differentiated by using HR-MRI. Here, we review the radiologic features of intracranial artery disease and cervical carotid artery atherosclerosis on HR-MRI and various other vessel wall imaging techniques (e.g., ultrasound, computed tomography, magnetic resonance, and positron emission tomography-computed tomography).

Antiplatelet treatment compared with anticoagulation treatment for cervical artery dissection (CADISS): a randomised trial

BACKGROUND

Extracranial carotid and vertebral artery dissection is an important cause of stroke, especially in young people. In some observational studies it has been associated with a high risk of recurrent stroke. Both antiplatelet drugs and anticoagulant drugs are used to reduce risk of stroke but whether one treatment strategy is more effective than the other is unknown. We compared their efficacy in the Cervical Artery Dissection in Stroke Study (CADISS), with the additional aim of establishing the true risk of recurrent stroke.

METHODS

We did this randomised trial at hospitals with specialised stroke or neurology services (39 in the UK and seven in Australia). We included patients with extracranial carotid and vertebral dissection with onset of symptoms within the past 7 days. Patients were randomly assigned (1:1) by an automated telephone randomisation service to receive antiplatelet drugs or anticoagulant drugs (specific treatment decided by the local clinician) for 3 months. Patients and clinicians were not masked to allocation, but investigators assessing endpoints were. The primary endpoint was ipsilateral stroke or death in the intention-to-treat population. The trial was registered with EUDract (2006-002827-18) and ISRN (CTN44555237).

FINDINGS

We enrolled 250 participants (118 carotid, 132 vertebral). Mean time to randomisation was 3·65 days (SD 1·91). The major presenting symptoms were stroke or transient ischaemic attack (n=224) and local symptoms (headache, neck pain, or Horner's syndrome; n=26). 126 participants were assigned to antiplatelet treatment versus 124 to anticoagulant treatment. Overall, four (2%) of 250 patients had stroke recurrence (all ipsilateral). Stroke or death occurred in three (2%) of 126 patients versus one (1%) of 124 (odds ratio [OR] 0·335, 95% CI 0·006-4·233; p=0·63). There were no deaths, but one major bleeding (subarachnoid haemorrhage) in the anticoagulant group. Central review of imaging failed to confirm dissection in 52 patients. Preplanned per-protocol analysis excluding these patients showed stroke or death in three (3%) of 101 patients in the antiplatelet group versus one (1%) of 96 patients in the anticoagulant group (OR 0·346, 95% CI 0·006-4·390; p=0·66).

INTERPRETATION

We found no difference in efficacy of antiplatelet and anticoagulant drugs at preventing stroke and death in patients with symptomatic carotid and vertebral artery dissection but stroke was rare in both groups, and much rarer than reported in some observational studies. Diagnosis of dissection was not confirmed after review in many cases, suggesting that radiographic criteria are not always correctly applied in routine clinical practice.

FUNDING

Stroke Association.

High-resolution MRI of the vessel wall in patients with symptomatic atherosclerotic stenosis of the middle cerebral artery

Intracranial atherosclerosis is associated with recurrent ischemic stroke. High-resolution MRI (HR MRI) can provide information about atheroma in vivo. We aimed to analyze and compare vascular wall imaging characteristics between patients with symptomatic and asymptomatic atherosclerotic stenosis of the middle cerebral artery (MCA) using 3.0 Tesla HR MRI. The HR MRI protocol included four different scans: black blood T1-weighted, T2-weighted and proton density-weighted MRI, as well as three-dimensional turbo spin echo imaging techniques with multiplanar reconstruction. Plaque characteristics, including location, morphology, and signal intensity, were analyzed in 51 patients (29 symptomatic, 22 asymptomatic) with atherosclerotic stenosis of the middle cerebral artery. The vessel wall area, lumen area, and plaque area (PA) were also calculated and compared between the symptomatic and asymptomatic groups. We found that PA, remodeling index (RI), and positive remodeling (PR) prevalence were significantly greater in the symptomatic group than in the asymptomatic group (PA: p=0.033; RI: p=0.020; PR: p=0.032). Plaque location in the superior aspect of the vessel wall and irregular plaque surface were more frequently observed in the symptomatic group than in the asymptomatic group (superior location: p=0.031; irregular surface: p=0.036). Moreover, multivariate logistic regression identified plaque location on the superior wall as an independent predictor of symptomatic MCA stenosis (odds ratio: 4.471; p=0.039). Therefore, we can conclude that patients with symptomatic atherosclerotic stenosis of the MCA are more likely to have larger plaques, PR, superiorly located plaques, and irregular plaque surface. These characteristics are promising factors for stratifying stroke risk.

Imaging of the carotid artery vulnerable plaque

Atherosclerosis involving the carotid arteries has a high prevalence in the population worldwide. This condition is significant because accidents of the carotid artery plaque are associated with the development of cerebrovascular events. For this reason, carotid atherosclerotic disease needs to be diagnosed and those determinants that are associated to an increased risk of stroke need to be identified. The degree of stenosis typically has been considered the parameter of choice to determine the therapeutical approach, but several recently published investigations have demonstrated that the degree of luminal stenosis is only an indirect indicator of the atherosclerotic process and that direct assessment of the plaque structure and composition may be key to predict the development of future cerebrovascular ischemic events. The concept of "vulnerable plaque" was born, referring to those plaque's parameters that concur to the instability of the plaque making it more prone to the rupture and distal embolization. The purpose of this review is to describe the imaging characteristics of "vulnerable carotid plaques."

The role of MRI as a prognostic tool in ischemic stroke

Magnetic resonance imaging (MRI) is an invaluable tool used in the diagnosis of ischemic stroke. Ongoing technological advances in MRI technology and advent of new imaging sequences has now made it possible to use MRI as a prognostic tool both in the acute and chronic stages of cerebral ischemia. This review summarizes the role of MRI in estimating final tissue outcome, specifically by providing information on severity and location of ischemic insult, cerebral blood flow dynamics, vascular status, and cerebral reserve. All of these predictions can then be used to make projections regarding clinical outcome, and can be refined by other prognostic models to estimate recovery and risk of further ischemic events. These algorithms, in the end, can ultimately help the clinician in tailoring therapies on an individual basis and optimize the risk-benefit ratio of therapeutic approaches used in the acute and chronic stages of ischemic stroke. The implementation of such prognostic algorithms to clinical imaging workstations and calculation of all the possible projections within minutes after completion of imaging are likely to become an integral part of clinical practice in the near future.

Plaque characteristics of asymptomatic carotid stenosis and risk of stroke

BACKGROUND

The optimal treatment of asymptomatic carotid stenosis (ACS) is controversial. To optimize the risk-benefit ratio of carotid artery revascularization, it is crucial to identify ACS patients who are at increased stroke risk. Recent data suggest that plaque vulnerability depends on its composition. Therefore, we assessed plaque composition in ACS to determine predictors for ipsilateral cerebrovascular events.

METHODS

62 patients with 65 ACS ≥50% underwent 3-T MRI of the carotid bifurcation (TOF, special dark-blood weighted noncontrast and contrast-enhanced T(1) and T(2) images) and of the brain. The different plaque components (lipid core, intraplaque hemorrhage, calcification and the status of the fibrous cap) were assessed. Furthermore, the plaque volume and the volume of clinically silent cortical and subcortical infarcts in the territory of the stenosed carotid artery as seen on FLAIR images were determined by using a semi-automated software. Carotid stenosis was considered asymptomatic if there had not been any clinically apparent ischemic events in the corresponding vascular territory within the previous 6 months. During follow-up, information on the occurrence of cerebrovascular events, medical treatment and sonographic changes of the stenosis was collected.

RESULTS

At baseline, 24 ACS (37%) were classified as high grade. A lipid-rich necrotic core was the dominant plaque component in 16 ACS (25%). The plaque volume was higher in ACS with a lipid-rich necrotic core as dominant plaque component (p = 0.002) and in patients with prior stroke/TIA (p = 0.010). After a median follow-up of 18.9 months (interquartile range 3.5-30.1) there were 2 ipsilateral strokes and 3 ipsilateral TIAs. The average annual event rate was 7.7%. A lipid-rich necrotic core (HR 7.21; 95% CI 1.12-46.28; p = 0.037), sonographic progression of the stenosis (HR 7.00; 95% CI 1.13-41.34; p = 0.036), history of stroke (HR 11.03; 95% CI 1.23-99.36; p = 0.032), and the volume of clinically asymptomatic ischemic brain lesions (HR 1.14/cm(3); 95% CI 1.03-1.25; p = 0.008) predicted cerebrovascular events. Patients on statin therapy at follow-up were at lower risk of events (HR 0.17; 95% CI 0.03-1.00; p = 0.05).

CONCLUSIONS

In addition to medical history and sonographic findings, a lipid-rich necrotic core within the plaque turned out as a predictor of cerebrovascular events. Therefore, MR imaging of carotid plaques deserves further attention and might be helpful to improve risk stratification of asymptomatic carotid disease. The identified predictors could be combined in a risk model and tested in larger prospective studies.

Brain and vascular imaging of acute stroke

Contemporary imaging technologies permit the rapid and accurate assessment of the acute stroke patient. These studies form the underpinning of all therapeutic approaches. Although unenhanced computed tomography remains the principal diagnostic examination to exclude hemorrhagic stroke, multimodal computed tomography and magnetic resonance imaging can be use to assess cerebral perfusion and may reveal the ischemic penumbra, thus leading to better patient selection for intravenous or intra-arterial reperfusion strategies.

Imaging assessment of cardiovascular risk in asymptomatic adults

OBJECTIVE

This article will address the role of coronary artery calcium (CAC) and carotid intima-media thickness screening in asymptomatic at-risk adults and the broader concept of vulnerable plaque as it applies to this population.

CONCLUSION

Imaging for assessment of cardiovascular risk in asymptomatic adults has been the subject of considerable interest and some controversy. The incorporation of CAC and carotid intima-media thickness assessment into recent guidelines reflects the growing evidence base for these applications.

Craniocervical arterial dissection in children: diagnosis and treatment

OPINION STATEMENT

Diagnosis of craniocervical arterial dissection (CCAD) in children begins with a careful history and physical in a child with a transient ischemic attack (TIA) or arterial ischemic stroke (AIS). The extent of radiologic evaluation for suspected CCAD is based upon careful consideration of the risks associated with the best imaging techniques, weighed against the benefits of enhanced vascular imaging with better diagnostic sensitivity. Although conventional angiography (CA) and CT angiography (CTA) have a higher sensitivity than magnetic resonance angiography (MRA), they are accompanied by risks: for CA, femoral hematoma, femoral arterial pseudoaneurysm, recurrent AIS, and radiation exposure; for CTA, radiation. For children (non-neonates) with suspected CCAD, MRI with MRA is recommended as the first-line imaging study. MRI usually includes diffusion-weighted, FLAIR, and T1 images of the brain, and T1 or T2 fat-saturation axial imaging through the neck. MRA should include 3D time-of-flight MRA of the head and neck (from the aortic arch through the circle of Willis). Contrast-enhanced MRA should be highly considered in neck imaging. If MRI/MRA is equivocal, CCAD is strongly suspected but not detected on MRI/MRA (especially in the posterior circulation), or the child has recurrent events, additional imaging of the craniocervical vasculature is likely warranted. Individual clinical circumstances warrant careful, case-by-case consideration. Treatment of CCAD in children is challenging and differs for intracranial and extracranial dissections. In extracranial CCAD, we most commonly use anticoagulation for 6 weeks to 6 months in patients with TIA or AIS. Typically, unfractionated heparin is used in the acutely ill patient at heightened risk for bleeding (because of its short half-life), whereas low-molecular-weight heparin (LMWH) or warfarin are reserved for the stable patient. If the history is suspicious for dissection (head and neck trauma, recent cervical chiropractic manipulation, recent car accident, or neck pain), we consider treatment for dissection even with normal MRI/MRA. For patients with CCAD with a stroke size greater than one third to one half of the middle cerebral artery territory (or other bleeding risk factors) and extracranial CCAD, in whom there is concern about heightened risk for hemorrhagic conversion, we commonly use aspirin therapy during the acute phase. Regardless of their treatment in the initial weeks to months, we subsequently treat all patients with aspirin for 1 year after their event, and sometimes longer if they have other risk factors. Interventional techniques, such as extracranial cerebral arterial stent placement or selective occlusion, are understudied in children. Interventional techniques are typically reserved for patients who fail aggressive medical management and have recurrent TIA or AIS. The diagnosis and treatment of intracranial dissection is extraordinarily challenging in children, in whom inflammatory intracranial arteriopathies are common. When intracranial arteriopathy is clearly associated with dissection, the clinician should look for the presence of subarachnoid hemorrhage and/or dissecting aneurysm. Treatment decisions should be made by a multidisciplinary pediatric stroke team, given the lack of data in this area. Intracranial cerebral artery stent placement carries high risk and is not recommended for intracranial CCAD in children. Most importantly, we educate all children with CCAD and their parents about the paucity of evidence in the treatment of this disease, the risks of enhanced imaging techniques such as CTA or CA, and the challenges involved in weighing the risks of aggressive therapies and interventions against the costs of unclear diagnosis and potentially ineffective treatments. We also educate our patients with CCAD about the signs and symptoms of recurrence and the importance of emergent evaluation.

Age determination of vessel wall hematoma in spontaneous cervical artery dissection: a multi-sequence 3T cardiovascular magnetic resonance study

BACKGROUND

Previously proposed classifications for carotid plaque and cerebral parenchymal hemorrhages are used to estimate the age of hematoma according to its signal intensities on T1w and T2w MR images. Using these classifications, we systematically investigated the value of cardiovascular magnetic resonance (CMR) in determining the age of vessel wall hematoma (VWH) in patients with spontaneous cervical artery dissection (sCAD).

METHODS

35 consecutive patients (mean age 43.6 ± 9.8 years) with sCAD received a cervical multi-sequence 3T CMR with fat-saturated black-blood T1w-, T2w- and TOF images. Age of sCAD was defined as time between onset of symptoms (stroke, TIA or Horner's syndrome) and the CMR scan. VWH were categorized into hyperacute, acute, early subacute, late subacute and chronic based on their signal intensities on T1w- and T2w images.

RESULTS

The mean age of sCAD was 2.0, 5.8, 15.7 and 58.7 days in patients with acute, early subacute, late subacute and chronic VWH as classified by CMR (p < 0.001 for trend). Agreement was moderate between VWH types in our study and the previously proposed time scheme of signal evolution for cerebral hemorrhage, Cohen's kappa 0.43 (p < 0.001). There was a strong agreement of CMR VWH classification compared to the time scheme which was proposed for carotid intraplaque hematomas with Cohen's kappa of 0.74 (p < 0.001).

CONCLUSIONS

Signal intensities of VWH in sCAD vary over time and multi-sequence CMR can help to determine the age of an arterial dissection. Furthermore, findings of this study suggest that the time course of carotid hematomas differs from that of cerebral hematomas.

[Sudden onset vertigo: imaging work-up]

Vertigo and dysequilibrium are a frequent cause of medical consultation. Clinical evaluation is essential. Some cases of vertigo are diagnosed clinically while others require imaging, sometimes emergently (suspected stroke). MRI is the imaging modality of choice to assess the labyrinth (labyrinthitis? labyrinthine hemorrhage?), internal auditory canal (vestibular schwannoma? other tumor?…) and brain parenchyma including all structures of the auditory pathways: vestibular nuclei, vestibulocerebellar tract, tracts involved with ocular motricity, vestibular cortex… Multiple central etiologies exist: stroke, multiple sclerosis, tumor… However, some etiologies are best depicted with CT, especially lesions of the labyrinth: cholesteatoma, trauma, suspected dehiscence of the superior semicircular canal, suspected labyrinthine fistula… Finally, imaging may be negative (Benign Paroxysmal Positional Vertigo, Meniere's disease, vestibular neuritis, migraine…), merely reducing the differential diagnosis.

Imaging of subclinical atherosclerosis: questions and answers

An increasingly important public health issue is the identification, stratification, and optimal management of individuals with subclinical atherosclerosis. This review addresses those aspects of noninvasive imaging of subclinical atherosclerosis that are most available and relevant to the practicing radiologist.

Pediatric stroke: clinical findings and radiological approach

This paper focuses on radiological approach in pediatric stroke including both ischemic stroke (Arterial Ischemic Stroke and Cerebral Sinovenous Thrombosis) and hemorrhagic stroke. Etiopathology and main clinical findings are examined as well. Magnetic Resonance Imaging could be considered as the first-choice diagnostic exam, offering a complete diagnostic set of information both in the discrimination between ischemic/hemorrhagic stroke and in the identification of underlying causes. In addition, Magnetic Resonance vascular techniques supply further information about cerebral arterial and venous circulation. Computed Tomography, for its limits and radiation exposure, should be used only when Magnetic Resonance is not available and on unstable patients.

3.0T MR Imaging of the Cranial Arterial Wall for the Strategy of Stroke Prevention

3.0T refined MRI reveals the anatomical structures clearly. Operative findings correspond well with MRI findings. The authors have used this equipment for prevention of stroke. Especially evaluation of the arterial wall is important for this purpose. Showing illustrative cases including operative ones, the authors discuss the MRI findings and strategy of treatment. The examinations of the Carotid artery (CA) and vertebro-basilar artery (VBA) were performed with 3.0T MRI (Philips Achiva 3.0T, Holland). Specialized sequences for each arterial wall were planned after TOF-MRA screening. The sequences include T1, T2 VISTA (3D Fatsaturation Volume ISotropic Turbospinecho Acquisition), mPROSET (Multiple Principle Selective Excitation Technique), B-FFE(Balanced Fast Field Echo) and T1 and T2 Black Blood. Intentionally directed pictures were acquired with reconstruction. Components of the plaque were estimated with the combination of the intensity of each picture. Distributions of carotid plaques were well demarcated and its components were diagnosed. Prognosis of each plaque was estimated and the surgical and/or non-surgical treatment plan was secured. Preoperative MRI plaque findings and the specimens from carotid endarterectomy (CEA) correlated well. The stability of the plaque could be evaluated, which afforded the decision of timing and method of operation. Lacerated walls of VBA dissection were well illustrated and strategies were planned. Intra-aneurysmal thrombus was revealed and its development was imaged. The wall of the unruptured aneurysm could be evaluated but not always. 3.0T MRI provides more anatomical and pathological information than conventional MRI. Prognosis of each lesion could be estimated. Routine examination of the cranial arterial wall contributes to the prevention of stroke.

Evaluation of inflammatory status of atherosclerotic carotid plaque before thromboendarterectomy using delayed contrast-enhanced subtracted images after magnetic resonance angiography

OBJECTIVE

To investigate the correlation among carotid plaque contrast enhancement (CPCE) at MRI, inflammatory cell infiltration (ICI) at histopathology, and carotid stenosis degree.

MATERIALS AND METHODS

Twenty-eight patients (19 males; mean age 67±9 years) scheduled for thromboendarterectomy prospectively underwent 1.5-T MR imaging using: (a) axial T1-weighted gradient-echo (T1wGRE) sequence centered on carotid bifurcations; (b) contrast-enhanced MR angiography (CE-MRA) with 0.1 mmol/kg of gadobenate dimeglumine; (c) enhanced axial T1wGRE sequence as in (a), 3 min after contrast injection. A three-point score system (absent, focal, wide) was used to assess CPCE on native and subtracted MRI images (c minus a) and ICI at histopathology. Carotid stenosis degree was determined on CE-MRA.

RESULTS

Six CPCE studies were discarded due to patient movement. In the remaining 22 studies, CPCE was absent, focal and wide in 13, 6 and 3 cases, respectively; ICI was absent, focal and wide in 13, 7 and 2 cases, respectively (k=0.57). On CE-MRA 21/28 stenoses were severe and 7/28 moderate. There was no correlation either with ICI (p=1.000, n=28) or CPCE (p=0.747, n=22).

CONCLUSION

The correlation between CPCE and ICI suggests a role for CPCE as an independent marker of plaque inflammation.

Added value of high-resolution MR imaging in the diagnosis of vertebral artery dissection

BACKGROUND AND PURPOSE

The optimal imaging method for the diagnosis of VAD remains undefined. Our aim was to evaluate the added value of HR-MR imaging for the diagnosis of VAD.

MATERIALS AND METHODS

We retrospectively extracted 35 consecutive patients suspected of having acute VAD who had the following: 1) a focal lumen abnormality of the VA on CE-MRA, 2) HR-MR imaging during the initial hospital stay, and 3) clinical and imaging follow-up within 6 months. Two neurologists classified patients as either VAD (group A) or non-VAD (group B) by reviewing all the available data at hospital discharge, except HR-MR imaging data. On HR-MR imaging, 2 radiologists searched for signs of acute VAD. The 2 classifications were compared. In case of discordance, CE-MRA follow-up and axial fat-suppressed T1WI, used to obtain supportive evidence for or against VAD, were considered as the standard of reference.

RESULTS

In 4/18 patients in group A, HR-MR imaging did not demonstrate any signs of acute VAD and perivertebral signal-intensity changes were attributed to venous plexus, with an unchanged lumen on follow-up. In 4/17 patients in group B, HR-MRI demonstrated a mural hematoma, with lumen normalization on follow-up CE-MRA.

CONCLUSIONS

Our results encourage the use of HR-MR imaging as a second-line diagnostic tool in the event of suspicion of acute VAD and doubtful findings on standard imaging.