Comparison of imaging findings on three-dimensional black-blood enhanced MR imaging between intracranial atherosclerotic occlusion and thrombotic occlusion.

PURPOSE: The purpose of this study was to compare the imaging findings on three-dimensional (3D) black-blood (BB) contrast-enhanced MR imaging between intracranial atherosclerotic occlusion (IAO) and thrombotic occlusion (TO) of the middle cerebral artery (MCA) territory. MATERIALS AND METHODS: From August 2020 to September 2021, we retrospectively reviewed the BB contrast-enhanced MR imaging of patients visiting the emergency room for evaluation of acute ischemic stroke. In total, 77 patients with complete occlusion of the MCA territory on 3D BB contrast-enhanced MR imaging and cerebral angiography were enrolled in this study. We divided the IAO and TO groups according to occlusion causes based on angiography findings. RESULTS: Of 77 patients, 44 (57.1%) had an IAO in the M1 and M2 and 33 had a TO. Lesion length contrast enhancement (CE) in patients with a TO was significantly longer than that in patients with an IAO (18.95 mm [IQR: 20.91] vs. 7.1 mm [8.92], p <0.001). Overall, 38 (39.4%) patients showed a disconnection of CE on 3D BB contrast-enhanced MR imaging, and 35 showed CE before and after the stenotic or thrombotic lesion. Symptomatic lesions on diffusion-weighted imaging in the TO group were significantly higher than that of the IAO group (97.0% vs, 70.5%, p = 0.003). CONCLUSION: The long segment CE on 3D BB contrast-enhanced MR imaging was related to TO of MCA. CE before and after a stenotic or thrombotic lesion is a common finding on 3D BB contrast-enhanced MR imaging.

Repeated Endovascular Thrombectomy in Patients with Acute Ischemic Stroke in a Single Center.

BACKGROUND: Patients with acute ischemic stroke treated with endovascular thrombectomy may be treated with repeat endovascular thrombectomy (rEVT) in case of recurrent large vessel occlusion (LVO). The purpose of this study is to report the frequency, timing, and outcomes of rEVT in a single center. MATERIALS AND METHODS: We retrospectively reviewed our databases for anterior or posterior circulation rEVT cases. Patient characteristics, procedural data, and functional outcomes (modified Rankin scale at 90 days) were analyzed. Early and late recurrence of stroke was divided at 30 days. RESULTS: Of 1025 patients treated between January 2011 and January 2020, 23 (2.2%) underwent rEVT. The median time between the first and second procedure was 185 days; 7 (30.4%) patients were re-treated within 30 days. Eleven patients (47.8%) had different occlusion sites between the two procedures. Good clinical outcome of patients with late ipsilateral recurrence was significantly higher than that of patients with late contralateral recurrence (83.3% vs. 16.7, p = 0.027). Overall good functional outcome after the second procedure was 43.5% (10/23). Overall good functional outcome of early and late recurrence groups were similar (57.1% vs. 37.5%, p = 0.650). One patient died due to an underlying cardiac problem. CONCLUSION: rEVT can be performed in patients with recurrent stroke of LVO. Ipsilateral recurrence of stroke was associated with good clinical outcome after rEVT.

Endovascular treatment of acute carotid atherosclerotic tandem occlusions: Predictors of clinical outcomes as technical aspects and location of tandem occlusions.

BACKGROUND: We aimed to analyze angiographic and clinical outcomes according to the sequence of treatment (antegrade versus retrograde) in patients with acute ischemic stroke caused by tandem extracranial cervical carotid and intracranial large vessel occlusion. MATERIALS AND METHODS: All eligible tandem occlusion patients from April 2012 to March 2019 undergoing carotid artery stenting (CAS) simultaneously with intracranial endovascular thrombectomy (EVT) were retrospectively reviewed. After dividing into 2 groups according to the treatment sequence for tandem lesions (antegrade, CAS first; retrograde, intracranial EVT first), baseline data, immediate angiographic results, and clinical outcome for eligible patients were analyzed and compared. In addition, the same analysis was performed after dividing into 3 groups based on the location of intracranial lesions (T-zone, M1, M2). RESULTS: A total of 76 patients with a tandem occlusion (mean age, 71.7 y± 11.1) were treated with CAS and intracranial EVT. The rate of successful recanalization (TICI 2BC) was 83% (63/76), and favorable functional outcome was achieved in 49% (37/76). When comparing antegrade and retrograde methods, there were no differences in baseline data and angiographic or clinical outcomes. Favorable functional outcome was significantly higher in the M2 occlusion group (P=0.011). In multivariate analysis, baseline NIHSS <15, age <80, and M2 occlusion were revealed as independent predictors of favorable outcome. CONCLUSION: Different endovascular sequences for tandem extracranial cervical carotid and intracranial large vessel occlusion do not affect angiographic or functional outcomes. Intracranial M2 occlusion, age, and baseline NIHSS were independent predictors of good clinical outcome at 3 months.

Correction to: Three-dimensional black-blood contrast-enhanced MRI improves detection of intraluminal thrombi in patients with acute ischaemic stroke.

The original version of this article, published on 19 March 2018, unfortunately contained a mistake. In the section "MR examination," the contrast medium Gadoterate meglumine was incorrectly named Gadodiamide.

Why is middle cerebral artery plaque augmented by contrast media? A phantom study using middle cerebral artery stenotic silicon model.

PURPOSE: The pathophysiologic mechanisms of contrast enhancement (CE) of middle cerebral artery (MCA) plaque remain unclear since histologic and imaging findings have never been compared. The purpose of this study was to assess the pattern of CE between patients with MCA stenosis or occlusion and in an MCA stenotic silicone model. METHODS: We retrospectively reviewed black blood (BB) contrast-enhanced T1-weighted (CE-T1W) imaging of patients who presented with acute stroke symptoms between January 2017 and January 2018. We subdivided the enrolled subjects according to whether the cerebral angiography findings suggested stenosis or occlusion. Silicone models were made with 4 degrees of MCA stenosis (stenotic area: 0.8 mm, 1.0 mm, 1.2 mm, and 1.4 mm) with a 3-mm lumen. BB CE-T1W imaging on silicone models with stenosis was obtained 5 min after contrast injection. RESULTS: During the period of this study, 19 patients with complete MCA occlusion and 22 with MCA stenosis, as shown by the cerebral angiography, were enrolled in this study. The CE of the silicone models with stenosis were 0.8 (74%) mm and 1.0 (66.7%) mm. The SI ratios of the CE of the plaque and the lumen were similar between the silicone models and the MCA stenosis/occlusion groups (silicone models: 31.0 ± 11.2; MCA occlusion: 27.6 ± 19.6; MCA stenosis: 22.8 ± 9.8). CONCLUSION: The silicone stenotic MCA model was characterized by luminal enhancement through contrast stagnation. The findings of the CE of the MCA plaque may be partially associated with stagnation of the contrast media.

Use of 3-Dimensional, Black-Blood, Contrast-Enhanced, T1-Weighted Magnetic Resonance Imaging to Identify Vascular Occlusion in the Posterior Circulation After Acute Ischemic Stroke.

BACKGROUND: Three-dimensional, black-blood, contrast-enhanced, T1-weighted magnetic resonance imaging (3D-BB-ceT1-MRI) could play a role in detection of thrombi and symptomatic intracranial atherosclerotic stenosis. We investigated the role of 3D-BB-ceT1-MRI in patients with acute ischemic stroke in the posterior circulation, and compared our findings with those from susceptibility-weighted imaging (SWI). MATERIALS AND METHODS: We retrospectively reviewed 3D-BB-ceT1-MRI for patients between January 2017 and August 2018 with acute ischemic symptoms in the posterior circulation. During this period, 199 patients with acute infarction in the posterior circulation were enrolled. Time-of-flight-magnetic resonance angiography or cerebral angiography was used as the reference standard. RESULTS: Of these 199 patients, 47 had vessel occlusion associated with acute infarction. The sensitivity of 3D-BB-ceT1-MRI for detection of vessel occlusion was significantly higher than that of SWI (95.7% versus 53.2%, P < .001). Twenty-one lesions with strong enhancement on 3D-BB-ceT1-MRI showed a negative susceptibility vessel sign (SVS) on SWI. CONCLUSIONS: 3D-BB-ceT1-MRI showed strong enhancement (due to contrast stagnation) in the intra-arterial thrombi of patients with acute infarction in the posterior circulation. 3D-BB-ceT1-MRI had higher sensitivity than that of an SVS on SWI for detection of intra-arterial thrombi.

Three-dimensional black-blood contrast-enhanced MRI improves detection of intraluminal thrombi in patients with acute ischaemic stroke.

OBJECTIVES: This study evaluated the utility of three-dimensional (3D), black-blood (BB), contrast-enhanced, magnetic resonance imaging (MRI) for the detection of intraluminal thrombi in acute stroke patients. METHODS: Forty-seven patients with acute stroke involving the anterior circulation underwent MRI examination within 6 h of clinical onset. Cerebral angiography was used as the reference standard. In a blinded manner, two neuroradiologists interpreted the following three data sets: (1) diffusion-weighted imaging (DWI) + 3D BB contrast-enhanced MRI; (2) DWI + susceptibility weighted imaging (SWI); (3) DWI + 3D BB contrast-enhanced MRI + SWI. RESULTS: Of these patients, 47 had clots in the middle cerebral artery and four had clots in the anterior cerebral artery. For both observers, the area under the curve (Az) for data sets 1 and 3, which included 3D BB contrast-enhanced MRI, was significantly greater than it was for data set 2, which did not include 3D BB contrast-enhanced MR imaging (observer 1, 0.988 vs 0.904, p = 0.001; observer 2, 0.988 vs 0.894, p = 0.000). CONCLUSIONS: Three-dimensional BB contrast-enhanced MRI improves detection of intraluminal thrombi compared to conventional MRI methods in patients with acute ischaemic stroke. KEY POINTS: • BB contrast-enhanced MRI helps clinicians to assess the intraluminal clot • BB contrast-enhanced MRI improves detection of intraluminal thrombi • BB contrast-enhanced MRI for clot detection has a higher sensitivity.

Widening and Rotation of Carotid Artery with Age: Geometric Approach.

BACKGROUND: The anatomy and geometry of the carotid artery may play an important role in the pathogenesis of internal carotid artery (ICA) stenosis, but the exact nature of this role remains elusive. To clarify this issue, we sought to investigate age-related changes in the anatomy and geometry of the carotid artery in a Korean population. MATERIALS AND METHODS: We conducted a retrospective study of 300 subjects who underwent carotid contrast-enhanced magnetic resonance angiography at our clinic between 2014 and 2016. The subjects were divided into 7 groups according to age. The carotid arteries were segmented using semiautomated methods to obtain various measurements of carotid anatomy and geometry, as suggested by Thomas et al. The various age groups were compared for different parameters, including ICA angle, bifurcation angle, and vessel volume and diameter. RESULTS: Analysis of variance showed that with an increase in age, there were significant increases in vessel volume and diameter of the common carotid artery and ICA as well as the carotid bifurcation (P = .000). Significant age-related increase was also noted in the ICA angle and bifurcation angle (P = .000). The anatomical position of the ICA in subjects aged over 60 years was significantly higher than that in subjects below 40 years (12.5% versus .03%, P < .0001). CONCLUSIONS: Age-related increases were noted in vessel volume and diameter of the carotid artery and ICA as well as the bifurcation angle. The widening and rotation of the carotid artery increased with age.

The Prognostic Value of CT-Angiographic Parameters After Reperfusion Therapy in Acute Ischemic Stroke Patients With Internal Carotid Artery Terminus Occlusion: Leptomeningeal Collateral Status and Clot Burden Score.

BACKGROUND: The objective of this study was to investigate the prognostic value of computed tomographic angiography (CTA) based on leptomeningeal collateral (LMC) status and other parameters in acute ischemic stroke (AIS) patients with internal carotid artery (ICA) terminus occlusion treated with endovascular treatment (EVT). METHODS: All eligible patients from January 2013 to December 2017 undergoing EVT were retrospectively reviewed. The regional leptomeningeal score was used to assess the LMCs on baseline CTA. The collateral status measured by the LMC score (0-20) was trichotomized into 3 groups: good (17-20), intermediate (11-16), and poor (0-10). RESULTS: Our sample included a total of 119 eligible patients (60 males; mean age, 73 years) with a median baseline National Institute of Health Stroke Scale (NIHSS) score of 14. Patients with a good LMC score had a lower baseline mean NIHSS score, a higher mean Alberta Stroke Program Early CT score, and a higher mean clot burden score (CBS). Baseline NIHSS score <15 (odds ratio [OR] 3.69 95% confidence ratio [CI]: 1.32-10.29, P = .013), CBS ≥ 6 (OR 3.97 95%CI: 1.05-14.99, P = .042), good LMC score (OR 5.14 95%CI: 1.62-16.26, P = .005) and successful recanalization (OR 11.55 95%CI: 2.72-48.99 P = .001) were independent predictors of good clinical outcomes. CONCLUSIONS: CTA-based LMC status and CBS are powerful predictors of clinical outcomes in patients with an acute ICA terminus occlusion treated with EVT.

Manual Aspiration Thrombectomy in Patients with Acute Stroke-Related Calcified Cerebral Emboli.

OBJECTIVE: The aim of this study was to evaluate the effectiveness of mechanical aspiration thrombectomy (MAT) in patients with acute ischemic stroke from calcified cerebral emboli. METHODS: Procedural results were reviewed for acute stroke patients with clinically neurological deficits who underwent recanalization from October 2012 through September 2015. Initial imaging studies and cerebral angiography were analyzed. RESULTS: Of the total number of patients with acute stroke, 5 patients were confirmed to have acute ischemic stroke by calcified cerebral emboli. On initial brain computed tomographic imaging, all patients showed small, dense single calcifications in the middle cerebral artery with no definitive ischemic low-density lesions (M1: 3, M2: 2, mean size: 4.8 mm). All patients had angiographic findings of filling defects from calcified emboli. Four patients had good collateral flow and two had continuous distal flow. All patients underwent MAT using a Penumbra catheter (Penumbra Inc., Alameda, CA). MAT did not remove calcified emboli in all patients. Two patients with good collateral flow had favorable functional outcomes (modified Rankin Scale score ≤2). Four patients had diffuse calcification in the aortic arch, carotid artery, and aortic valve. CONCLUSIONS: Cerebral angiography supports a diagnosis of stroke when calcified cerebral emboli have contrast-filling defects and a degree of vascular occlusion. However, in this study, MAT was not an effective treatment for patients with calcified cerebral emboli because of hardness of the calcified plaque and packing into the arterial lumen.

Association of Intraplaque Hemorrhage and Acute Infarction in Patients With Basilar Artery Plaque.

BACKGROUND AND PURPOSE: High-resolution magnetic resonance imaging (HRMRI) is ideal for serial examination of diseased arterial walls because it is noninvasive and has superior capability of discriminating tissue characteristics. The aim of this study is to evaluate the prevalence and clinical relevance of intraplaque hemorrhage (IPH) in patients with basilar artery (BA) atherosclerosis using HRMRI. METHODS: We analyzed HRMRI and clinical data from 74 patients (45 symptomatic and 29 asymptomatic), all of whom had >50% BA stenosis. High-signal intensity within a BA plaque on magnetization-prepared rapid acquisition with gradient-echo was defined as an area with an intensity that was >150% of the signal from the adjacent muscle. The relationship between IPH within a BA plaque region and clinical presentation was analyzed. RESULTS: Thirty patients were positive for IPH on HRMRI (42.3%, 24 symptomatic and 6 asymptomatic). Symptomatic lesions in the MR-positive IPH group were significantly more prevalent than in the MR-negative group (80.0% versus 48.8%; P<0.01). Also, MR-predicted IPH was significantly more prevalent in the high-grade stenosis group (P<0.001) than in the low-grade group. The relative risk of an acute focal stroke event among patients who were magnetization-prepared rapid acquisition with gradient-echo-positive for IPH compared with patients who were magnetization-prepared rapid acquisition with gradient-echo-negative was 1.64. CONCLUSIONS: IPH within a BA plaque region on HRMRI is highly prevalent and is associated with acute stroke.

Neuroanatomical mechanism on the effect of distraction in working memory maintenance in patients with schizophrenia.

This study utilized functional magnetic resonance imaging (fMRI) to discriminate brain activation patterns associated with the effect of distraction during working memory (WM) maintenance for human faces in healthy controls and patients with schizophrenia. Event-related fMRI data were obtained while the subjects performed WM maintenance in a delayed-response WM task with task-irrelevant distracters. Compared with healthy controls, patients showed significantly decreased activities in the superior frontal gyrus, dorsolateral prefrontal cortex (DLPFC), ventrolateral prefrontal cortex, anterior cingulate cortex, inferior parietal gyrus, and fusiform gyrus during the delayed-response WM task with human face distracters. The blood-oxygen-level-dependent signal changes in the DLPFC were negatively correlated with both of the scores of the Positive Subscale and General Psychopathology Subscale under the Positive and Negative Syndrome Scale during the WM maintenance for the human faces in the patients. This study will be helpful in understanding the neural mechanisms in the general impairment of the inhibition control in schizophrenia.

High-resolution magnetic resonance imaging of symptomatic middle cerebral artery dissection.

Dissection of the middle cerebral artery (MCA) is less frequent compared with dissection of vessels in the vertebrobasilar system or dissection of the carotid artery. High-resolution cross-sectional magnetic resonance imaging (HRMRI) has emerged as a potential technique for atherosclerotic plaque imaging in MCA. We enrolled 3 patients with MCA dissection on whom HRMRI was performed for evaluation of MCA stenosis. Two patients had an embolic infarction in the MCA territory and focal dissection. One patient had a massive infarction in the MCA territory and long-segment dissection of the MCA. On HRMRI, our objectives had an intimal flap with patency of the lumen and 1 had extensive hemorrhaging in the false lumen.

Can clinical and MRI findings predict the prognosis of variant and classical type of posterior reversible encephalopathy syndrome (PRES)?

BACKGROUND: Posterior reversible encephalopathy syndrome (PRES) is characterized by clinical symptoms that are associated with bilateral and symmetric vasogenic edema in the parietal and occipital lobes. However, this is rarely present with predominant involvement of the brain stem and cerebellum (variant). PURPOSE: To evaluate which clinical or magnetic resonance imaging (MRI) findings can help to predict the prognosis of variant and classical type of PRES and whether or not there is difference between two types of PRES. MATERIAL AND METHODS: We retrospectively evaluated MRI and clinical findings from 49 patients with PRES. These patients were divided into two groups. In group I, patients had atypical distribution of lesions. In group II, patients had typical distribution of lesions. Follow-up MRI was performed on 26 patients. We assessed the MRI features, clinical data, and the patients' outcomes. RESULTS: The mean blood pressure (BP) was significantly higher in group I (195.52/121.09 mmHg and 156.78/99.53 mmHg for groups I and II, respectively). The other factors assessed were not significantly different between the two groups. Lesions in 24 of 26 patients reversed upon follow-up. Sequelae were observed in 11 patients (group I, 7; group II, 4). However, there were no significant differences between the two groups. Except for those patients who died, seven of the nine patients with sequelae upon follow-up imaging had hemorrhage or irreversibility of lesions. CONCLUSION: Even though BP influences the involvement of the brain stem, involvement of the brain stem is not influential on the prognosis. It seems that the influential factor to prognosis is the reversibility of lesions and hemorrhage.

Aberrant Origin of the Distal Anterior Cerebral Artery from the Middle Cerebral Artery Related to Obstruction of Bilateral Proximal Anterior Cerebral Arteries: A Case Report.

BACKGROUND: Aberrant origin of the distal anterior cerebral artery (ACA) arising from the middle cerebral artery (MCA) is extremely rare. CASE PRESENTATION: A 74-year-old woman with a sudden onset of left-sided weakness was admitted to the emergency department. Angiography revealed an unusual course of the distal ACA originating from the MCA with bilateral obstruction of the proximal segment of the ACA and simultaneous occurrence of infarction in the ACA and MCA territories. CONCLUSION: Knowledge of a rare vascular variation or anomaly could help understand brain imaging, which has an unusual involvement of vascular territories, performed in patients with acute ischemic stroke.

The role of vessel wall imaging in determining the best treatment approach for coexisting aneurysms and subarachnoid hemorrhage.

PURPOSE: The purpose of this study was to investigate the utilization of gadolinium enhancement on vessel wall imaging (VWI) in treatment decision-making for patients with two intracranial aneurysms presenting as a subarachnoid hemorrhage (SAH). MATERIALS AND METHODS: We prospectively performed VWI using 3.0-Tesla (3T) magnetic resonance imaging (MRI) before treatment with endovascular coiling or surgical clipping in patients with one or two intracranial aneurysms. The VWI protocol includes three different scans: black blood (BB) T1-weighted, BB T2-weighted, TOF axial, and BB contrast-enhanced T1-weighted imaging. We analyzed all aneurysm ruptures both with and without gadolinium enhancement of the aneurysm wall. RESULTS: Thirty-eight patients with 48 aneurysms were enrolled in this study. Of these patients, 28 had a single aneurysm (15 ruptured and 13 unruptured), and 10 had two aneurysms and SAH (9 patients with two aneurysms and 1 patient with three aneurysms). Of the 15 single ruptured aneurysms, 12 (80.0%) showed positive wall enhancement, whereas 2 of the 13 single unruptured aneurysms (15.4%) demonstrated positive wall enhancement. Ten patients with SAH and two aneurysms showed wall enhancement of a single aneurysm, and these aneurysms were treated first. CONCLUSION: Gadolinium enhancement of an aneurysm wall on MRI was associated with aneurysm rupture. In patients with two aneurysms and SAH, this type of imaging can play an important role in determining the order of aneurysm treatment.

The comprehensive comparison of imaging sign from CT angiography and noncontrast CT for predicting intracranial hemorrhage expansion: A comparative study.

Expansion of intracranial hemorrhage (ICH) is an important predictor of poor clinical outcomes. Various imaging markers on non-contrast computed tomography (NCCT) or computed tomographic angiography (CTA) have been reported as predictors of ICH expansion. We aimed to compare the associations between various CT imaging markers and ICH expansion. Patients with spontaneous ICH who underwent initial NCCT, CTA, and subsequent NCCT between January 2016 and December 2019 were retrospectively identified. ICH expansion was defined as a volume increase of > 33% or > 6 mL. We analyzed the presence of imaging markers such as the black hole sign, blend sign, island sign, or swirl sign on initial NCCT or spot sign on CTA. An alternative free-response receiver operating characteristic curve analysis was performed using a 4-point scoring system based on the consensus of the reviewers. The predictive value of each marker was assessed using univariate and multivariate logistic regression analyses. A total of 250 patients, including 60 (24.0%) with ICH expansion, qualified for the analysis. Among the patients with spontaneous ICH, 118 (47.2%) presented with a black hole sign, 52 (20.8%) with a blend sign, 93 (37.2%) with an island sign, 79 (31.6%) with a swirl sign, and 56 (22.4%) with a spot sign. In univariate logistic regression, the initial ICH volume (P = .038), initial intraventricular hemorrhage (IVH) presence (P < .001), swirl sign (P < .001), and spot sign (P < .001) were associated with ICH expansion. Multivariate analysis confirmed that the presence of initial IVH (odds ratio, 4.111; P = .002) and spot sign (odds ratio, 109.5; P < .001) were independent predictors of ICH expansion. Initial ICH volume, IVH, swirl sign, and spot sign are associated with ICH expansion. The presence of spot signs and IVH were independent predictors of ICH expansion.

Prevalence of Symptomatic Nonstenotic Carotid Disease Using Simultaneous Non-Contrast Angiography and Intraplaque Hemorrhage Imaging for MR Screen Protocol.

Background: To determine the prevalence of symptomatic nonstenotic carotid disease (SyNC) using simultaneous non-contrast angiography and intraplaque hemorrhage (SNAP) imaging for patients with acute stroke as an MR screen protocol and to assess imaging findings of carotid plaques. Patients and Methods: From May 2020 to October 2021, 2459 patients with suspected acute neurological symptoms were evaluated with brain diffusion-weighted imaging (DWI) and carotid SNAP imaging. We analyzed the degree of stenosis and intraplaque hemorrhage (IPH) using SNAP imaging. Prevalence of SyNC and risk factors for stroke in patients with SyNC were determined. We performed subgroup multivariate analysis between SyNC and other etiologies of stroke (non-SyNC). Results: Of 4608 carotid arteries in 2304 patients enrolled in this study, 454 (9.9%) plaques (both lesions in 128 patients) were found on SNAP imaging. Of these plaques, 353 (77.8%) showed stenosis of <50%. Of plaques with <50% stenosis, 47 (13.3%) patients had a territorial acute focal infarction. Seventeen (36.2%) were classified with embolic stroke of undetermined source (ESUS) and SyNC. High maximal wall thickness and carotid IPH were identified as influencing factors for SyNC. Conclusion: For patients with <50% stenosis and territorial infarction, SyNC is a relatively important source of stroke. Especially, high maximal wall thickness and carotid IPH are important risk factors for SyNC.

Acute Distal Vertebral Artery Occlusion in Patients with Asymmetrical Vertebral Artery Geometry: Role of Black-Blood-Enhanced MR Imaging.

Background: The purpose of this study was to evaluate the diagnostic value of contrast enhancement in a unilateral distal vertebral artery (VA) using black blood (BB)-enhanced magnetic resonance (MR) imaging in patients with acute neurological symptoms and asymmetrical VA geometry. Methods: From January 2020 to August 2021, we retrospectively analyzed BB-contrast-enhanced MR imaging and MR angiography (MRA) findings in stroke patients visiting the emergency room for an evaluation of acute neurological symptoms. We classified four patterns according to asymmetrical VA geometry using MRA and contrast enhancement using BB-enhanced MR imaging: type 1 = enhanced VA + no visualization of VA, type 2 = enhanced VA + hypoplastic VA, type 3 = non-enhanced VA + hypoplastic VA, or type 4 = non-enhanced VA + no visualization of VA. Results: In total, 288 patients (type 1 = 65, type 2 = 17, type 3 = 130, type 4 = 76) were enrolled in this study. Of these patients, 82 (28.5%) showed contrast enhancement of a unilateral distal VA on BB-enhanced MR imaging, and 51 (17.8%) had positive findings on diffusion-weighted imaging (DWI) in the ipsilateral medulla, pons, or posterior inferior cerebellar artery (PICA) territory. The contrast enhancement of a unilateral distal VA using BB-enhanced MR imaging demonstrated a significantly higher prevalence in patients with acute infarction on DWI (50.0% vs. 4.9%, p < 0.001). Conclusions: The contrast enhancement of a unilateral distal VA on BB-enhanced MR imaging is associated with acute infarction of the medulla, pons, or PICA territory and suggests acute occlusion of a distal VA.

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.