Quantification of steal flow on Doppler ultrasound in patients with arteriovenous graft for hemodialysis.

PURPOSE: Arteriovenous fistula (AVF) is the preferred treatment for long-term hemodialysis patients to allow reliable vascular access. Arteriovenous graft (AVG) is monitored using Doppler sonography to check a vessel's condition and predict complications such as steal syndrome. In this study, we developed an analysis algorithm and method to quantify steal syndrome using Doppler sonography. METHODS: Doppler sonography was used to determine the pattern of anterograde and retrograde flow. The ratio of blood volumes was calculated with a vision analysis software. First, performance of the developed algorithm was validated by comparing it with commercial Doppler sonography data. Doppler sonography was performed for an artificial vessel to analyze the steal flow. RESULTS: A total of 58 patients with steal flow were enrolled in this study. Of these patients, 23 did not have a difference in fingertip temperature between both sides. The median difference in temperature of 35 patients was 0.8°C (range, 0.3-1.9°C). The ratio of retrograde flow volume/antegrade flow volume in patients with the presence of temperature difference was significantly higher compared to that in patients without the temperature difference (p < .001). The ROC curve for the difference in flow volume had an AUC of 0.770. The optimal cutoff of difference in the flow volume between the two groups was 0.24 (sensitivity of 91.4 % and specificity of 52.2%). The flow volume difference was significantly positively correlated to temperature difference (r = 0.487, p < .003). CONCLUSION: Our algorithm could measure steal flow volume of a bidirectional waveform by antegrade arterial flow and retrograde reversal flow.

Post-diffusion and perfusion magnetic resonance imaging of emboli to distal territories after endovascular thrombectomy.

BACKGROUND AND PURPOSE: This study aimed to investigate the clinical outcomes of emboli to distal territories (EDT) after aspiration thrombectomy in patients with acute anterior circulation occlusion. MATERIALS AND METHODS: From January 2016 to December 2022, all eligible patients who underwent endovascular treatment (EVT) due to acute anterior circulation occlusion were retrospectively reviewed. During this period, patients with EDT after EVT underwent magnetic resonance (MR) perfusion with angiography and diffusion-weighted imaging within 12 hours from recanalization. Hypoperfusion was defined as a Tmax value > 6-second volume. RESULTS: Of the 104 eligible patients (65 males, median age 74 years), 79 (76.0 %; 2a: 19, 2b: 55, 2c: 5) had hypoperfusion on perfusion MR (PWI). Complete mismatch on diffusion-weighted imaging (DWI) of the hypoperfusion area was significantly higher in patients with successful recanalization than in patients with incomplete recanalization (58.3 % vs. 31.6 %, p = 0.0437). Of the 79 patients with hypoperfusion, 24 had EDT in the M2, 39 in the M3, and 16 in the M4. Complete mismatch on DWI and PWI was significantly higher in patients with a distal EDT (M3 or M4) than in patients with an M2 EDT (65.8 % vs. 20.8 %, p < 0.001). CONCLUSIONS: EDT to the M3 or more distal branches after EVT had a higher rate of complete DWI-PWI mismatch on early follow-up MRI than EDT to M2.

Geometric versus Hemodynamic Indexes for Rupture-Destined Aneurysms: A Retrospective Cohort and a Repeated-Measures Study.

INTRODUCTION: A proper stratification of intracranial aneurysms is critical in identifying rupture-destined aneurysms and unruptured intracranial aneurysms. We aimed to determine the utility of geometric and hemodynamic indexes in differentiating two types of aneurysms and to examine the characteristics of natural evolutionary changes of unruptured aneurysms. METHODS: Rupture-destined aneurysm refers to an aneurysm that undergoes subsequent aneurysmal subarachnoid hemorrhage (SAH). On the other hand, an unruptured intracranial aneurysm is characterized by an aneurysm that does not experience rupture during serial time-of-flight magnetic resonance angiography (TOF-MRA). In addition to geometric indexes, signal intensity gradient (SIG), an in vivo approximated wall shear stress from TOF-MRA, was measured in aneurysms. The difference between the maximum and minimum values of SIG in an aneurysm compared to parent arterial values was designated as the delta-SIG ratio. RESULTS: This study analyzed 20 rupture-destined aneurysms in 20 patients and 45 unruptured intracranial aneurysms in 41 patients with follow-up TOF-MRA. While geometric indexes did not show differences between the two groups, the delta-SIG ratio was higher in the rupture-destined aneurysms (1.5 ± 0.6 vs. 1.1 ± 0.3, p = 0.032). The delta-SIG ratio showed a higher area under the receiver operating characteristic curve for SAH than the size ratio (0.72 [95% CI, 0.58-0.87] vs. 0.56 [95% CI, 0.41-0.72], p = 0.033). The longitudinal re-examination of TOF-MRA in the unruptured intracranial aneurysms revealed evidence of aneurysmal growth, while concurrently exhibiting hemodynamic stability. CONCLUSION: The delta-SIG ratio showed higher discriminatory results between the two groups compared to geometric indexes. Aneurysmal rupture risk should be assessed by considering both geometric and hemodynamic information. This study was registered on ClinicalTrials.gov (NCT05450939).

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.

Mechanical Thrombectomy in Basilar Artery Occlusion: Clinical Outcomes Related to Posterior Circulation Collateral Score.

BACKGROUND AND PURPOSE: Basilar artery occlusion (BAO) is associated with a high risk of disability and mortality. The objective of this study was to investigate prognostic factors in patients with acute basilar artery occlusion treated with mechanical thrombectomy, focusing on collateral status and recanalization time from symptom onset. METHODS: Eligible patients from January 2012 to October 2019 who underwent endovascular treatment due to acute BAO were reviewed. The baseline posterior circulation collateral status was assessed with the basilar artery on computed tomography angiography score and posterior circulation collateral score. Good outcomes were defined as a modified Rankin Scale score of ≤2 at 3 months and successful recanalization as Thrombolysis in Cerebral Infarction grades 2b, 3. The associations between baseline and clinical parameters and favorable outcomes were evaluated with logistic regression. RESULTS: Our sample included a total of 81 eligible patients (49 males, mean age 70.3 years) with a median baseline and discharge National Institutes of Health Stroke Scale score of 12. Patients with good outcomes showed a lower baseline National Institutes of Health Stroke Scale score, a greater proportion of distal BAO, and a higher basilar artery on computed tomography angiography and posterior circulation collateral score (P<0.001). According to subgroup analysis of patients within and over 6 or 12 hours, the time from symptom onset to recanalization was not correlated with good outcomes. Multivariable logistic analysis showed baseline National Institutes of Health Stroke Scale <15 (odds ratio, 8.49 [95% CI, 2.01-35.82]; P=0.004), posterior circulation collateral score ≥6 (odds ratio, 3.79 [95% CI, 1.05-13.66]; P=0.042), and distal BAO (odds ratio, 3.67 [95% CI, 1.10-12.26]; P=0.035) were independent predictors of good outcomes. CONCLUSIONS: This study suggested that good collateral circulation and distal BAO are independent predictors of clinical outcome after endovascular treatment in patients with acute BAO. In particular, patients with good initial collateral status and distal BAO may consider endovascular treatment even if the treatment is started beyond the standard time limits.

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.

Balloon Guide Catheter Is Beneficial in Endovascular Treatment Regardless of Mechanical Recanalization Modality.

Background and Purpose- Based on its mechanism, the use of balloon guide catheters (BGCs) may be beneficial during endovascular treatment, regardless of the type of mechanical recanalization modality used-stent retriever thrombectomy or thrombaspiration. We evaluated whether the use of BGCs can be beneficial regardless of the first-line mechanical endovascular modality used. Methods- We retrospectively reviewed consecutive acute stroke patients who underwent stent retriever thrombectomy or thrombaspiration from the prospectively maintained registries of 17 stroke centers nationwide. Patients were assigned to the BGC or non-BGC group based on the use of BGCs during procedures. Endovascular and clinical outcomes were compared between the BGC and non-BGC groups. To adjust the influence of the type of first-line endovascular modality on successful recanalization and favorable outcome, multivariable analyses were also performed. Results- This study included a total of 955 patients. Stent retriever thrombectomy was used as the first-line modality in 526 patients (55.1%) and thrombaspiration in 429 (44.9%). BGC was used in 516 patients (54.0%; 61.2% of stent retriever thrombectomy patients; 45.2% of thrombaspiration patients). The successful recanalization rate was significantly higher in the BGC group compared with the non-BGC group (86.8% versus 74.7%, respectively; P<0.001). Furthermore, the first-pass recanalization rate was more frequent (37.0% versus 14.1%; P<0.001), and the number of device passes was fewer in the BGC group (2.5±1.9 versus 3.3±2.1; P<0.001). The procedural time was also shorter in the BGC group (54.3±27.4 versus 67.6±38.2; P<0.001). The use of BGC was an independent factor for successful recanalization (odds ratio, 2.18; 95% CI, 1.54-3.10; P<0.001) irrespective of the type of first-line endovascular modality used. The use of BGC was also an independent factor for a favorable outcome (odds ratio, 1.40; 95% CI, 1.02-1.92; P=0.038) irrespective of the type of first-line endovascular modality used. Conclusions- Regardless of the first-line mechanical endovascular modality used, the use of BGC in endovascular treatment was beneficial in terms of both recanalization success and functional outcome.

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.

Longitudinal study of carotid artery bifurcation geometry using magnetic resonance angiography.

OBJECTIVES: Geometry of carotid artery has been known as a risk factor for atherosclerotic carotid disease. Though aging and disease progression can both attribute to geometric changes in the arteries, the exact nature of this phenomenon remains elusive. The aim of our study was to investigate carotid artery geometric changes in a longitudinal study. METHODS: We conducted a retrospective study of 114 subjects who underwent carotid contrast-enhanced magnetic resonance angiography at our clinic at baseline (2005 to 2007) and after 10 years. The right carotid arteries were segmented using semi-automated methods to obtain various measurements of carotid artery geometry. For each patient, these parameters were assessed at both time points, including bifurcation angle, internal carotid artery angle, vessel diameter, and circumference. RESULTS: The median age for the total patient population ( n = 114) at baseline was 59.06 ± 10.40 years. Mean time interval between baseline magnetic resonance angiography and magnetic resonance angiography after 10 years of these patients was 129.18 ± 7.77 months. For the whole group, there was a significant increase in the bifurcation angle ( p < 0.05) over a 10-year period. A significant increase was also noted in the diameter and circumference of the common carotid artery ( p < 0.05). However, the other vessel diameters and circumferences (bulb carotid, internal carotid) as well as the internal carotid angle did not significantly change ( p ≥ 0.05). CONCLUSIONS: The diameter and circumference of the common carotid artery and bifurcation angle significantly increased over a decade of life.

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.

Number of Stent Retriever Passes Associated With Futile Recanalization in Acute Stroke.

Background and Purpose- Stent retriever (SR) thrombectomy has become the mainstay of treatment of acute intracranial large artery occlusion. However, it is still not much known about the optimal limit of SR attempts for favorable outcome. We evaluated whether a specific number of SR passes for futile recanalization can be determined. Methods- Patients who were treated with a SR as the first endovascular modality for their intracranial large artery occlusion in anterior circulation were retrospectively reviewed. The recanalization rate for each SR pass was calculated. The association between the number of SR passes and a patient's functional outcome was analyzed. Results- A total of 467 patients were included. Successful recanalization by SR alone was achieved in 82.2% of patients. Recanalization rates got sequentially lower as the number of passes increased, and the recanalization rate achievable by ≥5 passes of the SR was 5.5%. In a multivariable analysis, functional outcomes were more favorable in patients with 1 to 4 passes of the SR than in patients without recanalization (odds ratio [OR] was 8.06 for 1 pass; OR 7.78 for 2 passes; OR 6.10 for 3 passes; OR 6.57 for 4 passes; all P<0.001). However, the functional outcomes of patients with ≥5 passes were not significantly more favorable than found among patients without recanalization (OR 1.70 with 95% CI, 0.42-6.90 for 5 passes, P=0.455; OR 0.33 with 0.02-5.70, P=0.445 for ≥6 passes). Conclusions- The likelihood of successful recanalization got sequentially lower as the number of SR passes increased. Five or more passes of the SR became futile in terms of the recanalization rate and functional outcomes.

Rescue Stenting for Failed Mechanical Thrombectomy in Acute Ischemic Stroke: A Multicenter Experience.

BACKGROUND AND PURPOSE: Effective rescue treatment has not yet been suggested in patients with mechanical thrombectomy (MT) failure. This study aimed to test whether rescue stenting (RS) improved clinical outcomes in MT-failed patients. METHODS: This is a retrospective analysis of the cohorts of the 16 comprehensive stroke centers between September 2010 and December 2015. We identified the patients who underwent MT but failed to recanalize intracranial internal carotid artery or middle cerebral artery M1 occlusion. Patients were dichotomized into 2 groups: patients with RS and without RS after MT failure. Clinical and laboratory findings and outcomes were compared between the 2 groups. It was tested whether RS is associated with functional outcome. RESULTS: MT failed in 148 (25.0%) of the 591 patients with internal carotid artery or middle cerebral artery M1 occlusion. Of these 148 patients, 48 received RS (RS group) and 100 were left without further treatment (no stenting group). Recanalization was successful in 64.6% (31 of 48 patients) of RS group. Compared with no stenting group, RS group showed a significantly higher rate of good outcome (modified Rankin Scale score, 0-2; 39.6% versus 22.0%; P=0.031) without increasing symptomatic intracranial hemorrhage (16.7% versus 20.0%; P=0.823) or mortality (12.5% versus 19.0%; P=0.360). Of the RS group, patients who had recanalization success had 54.8% of good outcome, which is comparable to that (55.4%) of recanalization success group with MT. RS remained independently associated with good outcome after adjustment of other factors (odds ratio, 3.393; 95% confidence interval, 1.192-9.655; P=0.022). Follow-up vascular imaging was available in the 23 (74.2%) of 31 patients with recanalization success with RS. The stent was patent in 20 (87.0%) of the 23 patients. Glycoprotein IIb/IIIa inhibitor was significantly associated with stent patency but not with symptomatic intracranial hemorrhage. CONCLUSIONS: RS was independently associated with good outcomes without increasing symptomatic intracranial hemorrhage or mortality. RS seemed considered in MT-failed internal carotid artery or middle cerebral artery M1 occlusion.

Collateral status affects the onset-to-reperfusion time window for good outcome.

OBJECTIVE: To characterise the time window in which endovascular thrombectomy (EVT) is associated with good outcome, and to test the differential relationship between functional outcome and onset-to-reperfusion time (ORT), depending on collateral status. METHODS: This was a retrospective analysis of clinical and imaging data of 554 consecutive patients, who had recanalisation success by EVT for anterior circulation large artery occlusion, from the prospectively maintained registries of 16 comprehensive stroke centres between September 2010 and December 2015. The patients were dichotomised into good and poor collateral groups, based on CT angiography. We tested whether the likelihood of good outcome (modified Rankin Scale, 0-2) by ORT was different between two groups. RESULTS: ORT was 298 min±113 min (range, 81-665 min), and 84.5% of patients had good collaterals. Age, diabetes mellitus, previous infarction, National Institutes of Health Stroke Scale, good collaterals (OR 40.766; 95% CI 10.668 to 155.78; p<0.001) and ORT (OR 0.926 every 30 min delay; 95% CI 0.862 to 0.995; p=0.037) were independently associated with good outcome. The drop in likelihood of good outcome associated with longer ORT was significantly faster in poor collateral group (OR 0.305 for every 30 min; 95% CI 0.113 to 0.822) than in good collateral group (OR 0.926 for every 30 min; 95% CI 0.875 to 0.980). CONCLUSIONS: Earlier successful recanalisation was strongly associated with good outcome in poor collateral group; however, this association was weak during the tested time window in good collateral group. This suggests that the ORT window for good outcome can be adjusted according to collateral status.

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.

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.

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.

Diffusion-weighted MR imaging of upper abdominal organs at different time points: Apparent diffusion coefficient normalization using a reference organ.

PURPOSE: To compare the apparent diffusion coefficient (ADC) of upper abdominal organs acquired at different time points, and to investigate the usefulness of normalization. MATERIALS AND METHODS: We retrospectively evaluated 58 patients who underwent three rounds of magnetic resonance (MR) imaging including diffusion-weighted imaging of the upper abdomen. MR examinations were performed using three different 3.0 Tesla (T) and one 1.5T systems, with variable b value combinations and respiratory motion compensation techniques. The ADC values of the upper abdominal organs from three different time points were analyzed, using the ADC values of the paraspinal muscle (ADCpsm ) and spleen (ADCspleen ) for normalization. Intraclass correlation coefficients (ICC) and comparison of dependent ICCs were used for statistical analysis. RESULTS: The ICCs of the original ADC and ADCpsm showed fair to substantial agreement, while ADCspleen showed substantial to almost perfect agreement. The ICC of ADCspleen of all anatomical regions showed less variability compared with that of the original ADC (P < 0.005). CONCLUSION: Normalized ADC using the spleen as a reference organ significantly decreased variability in measurement of the upper abdominal organs in different MR systems at different time points and could be regarded as an imaging biomarker for future multicenter, longitudinal studies. LEVEL OF EVIDENCE: 5 J. MAGN. RESON. IMAGING 2017;45:1494-1501.

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.