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Background: Undetermined stroke etiology hampers optimal secondary prevention in a large proportion of young patients. We explored whether genetic screening for clonal hematopoiesis of indetermined potential (CHIP), a novel risk factor for stroke, could identify patients with myeloid precursor lesions or covert myeloid neoplasm requiring specific treatment. Methods: We performed targeted sequencing on 56 genes recurrently mutated in hematologic neoplasms in a prospective cohort of patients with acute brain ischemia between 18 and 60 years. CHIP prevalence was compared with age-matched healthy controls from the Nijmegen Biomedical Study (n=1604) and the UK Biobank (n=101 678). Patients with suspicion of high-risk CHIP or myeloid neoplasm were invited for further hematologic evaluation. Results: We included 248 consecutive patients (39% women) of whom 176 (71%) had cryptogenic stroke etiology. Fifty-one (21%) patients had CHIP, 3-fold more than in the general population (7.7% versus 2.6% for the Nijmegen Biomedical Study and 11.9% versus 4.1% for UK Biobank; P P P =0.009), and had higher burden of atherosclerosis (29.4% versus 16.7%; P =0.04). We invited 11 patients (4.4%) for further hematologic assessment, which in 7 led to the diagnosis of high-risk CHIP and in 2 to the new diagnosis of a myeloproliferative neoplasm with indication for cytoreductive therapy. Conclusions: Using genetic screening for myeloid disorders in patients with stroke of predominantly undetermined etiology, we found a 3-fold higher CHIP prevalence than in the general population. We identified high-risk CHIP and previously covert myeloproliferative neoplasms as potential stroke etiologies in 4.4% and 1% of patients, respectively. Our findings demonstrate the diagnostic and therapeutic yield of genetic screening in young patients with stroke. Future studies should investigate the role of CHIP for stroke recurrence and optimal secondary prevention.

Selective therapeutic hypothermia (TH) showed promising preclinical results as a neuroprotective strategy in acute ischemic stroke. We aimed to assess safety and feasibility of an intracarotid cooling catheter conceived for fast and selective brain cooling during endovascular thrombectomy in an ovine stroke model. Transient middle cerebral artery occlusion (MCAO, 3 h) was performed in 20 sheep. In the hypothermia group (n = 10), selective TH was initiated 20 minutes before recanalization, and was maintained for another 3 h. In the normothermia control group (n = 10), a standard 8 French catheter was used instead. Primary endpoints were intranasal cooling performance (feasibility) plus vessel patency assessed by digital subtraction angiography and carotid artery wall integrity (histopathology, both safety). Secondary endpoints were neurological outcome and infarct volumes. Computed tomography perfusion demonstrated MCA territory hypoperfusion during MCAO in both groups. Intranasal temperature decreased by 1.1 °C/3.1 °C after 10/60 minutes in the TH group and 0.3 °C/0.4 °C in the normothermia group (p Selective TH was feasible and safe. However, a larger number of subjects might be required to demonstrate efficacy.

Complicated nonstenosing carotid artery plaques (CAPs) are an under-recognized cause of stroke.The purpose of this study was to determine whether complicated CAP ipsilateral to acute ischemic anterior circulation stroke (icCAP) are associated with recurrent ischemic stroke or transient ischemic attack (TIA).The CAPIAS (Carotid Plaque Imaging in Acute Stroke) multicenter study prospectively recruited patients with ischemic stroke restricted to the territory of a single carotid artery. Complicated (AHA-lesion type VI) CAP were defined by multisequence, contrast-enhanced carotid magnetic resonance imaging obtained within 10 days from stroke onset. Recurrent events were assessed after 3, 12, 24, and 36 months. The primary outcome was recurrent ischemic stroke or TIA.Among 196 patients enrolled, 104 patients had cryptogenic stroke and nonstenosing CAP. During a mean follow-up of 30 months, recurrent ischemic stroke or TIA occurred in 21 patients. Recurrent events were significantly more frequent in patients with icCAP than in patients without icCAP, both in the overall cohort (incidence rate [3-year interval]: 9.50 vs 3.61 per 100 patient-years; P = 0.025, log-rank test) and in patients with cryptogenic stroke (10.92 vs 1.82 per 100 patient-years; P = 0.003). The results were driven by ipsilateral events. A ruptured fibrous cap (HR: 4.91; 95% CI: 1.31-18.45; P = 0.018) and intraplaque hemorrhage (HR: 4.37; 95% CI: 1.20-15.97; P = 0.026) were associated with a significantly increased risk of recurrent events in patients with cryptogenic stroke.Complicated CAP ipsilateral to acute ischemic anterior circulation stroke are associated with an increased risk of recurrent ischemic stroke or TIA. Carotid plaque imaging identifies high-risk patients who might be suited for inclusion into future secondary prevention trials. (Carotid Plaque Imaging in Acute Stroke [CAPIAS]; NCT01284933).

BACKGROUND Hemodynamic alterations of extracranial veins are considered an etiologic factor in multiple sclerosis (MS). However, ultrasound and MRI studies could not confirm a pathophysiological link. Because of technical challenges using standard diagnostics, information about the involvement of superficial intracranial veins in proximity to the affected brain in MS is scarce. PURPOSE To comprehensively investigate the hemodynamics of intracranial veins and of the venous outflow tract in MS patients and controls. STUDY TYPE Prospective. POPULATION Twenty-eight patients with relapsing-remitting MS (EDSS1.9 ± 1.1; range 0-3) and 41 healthy controls. FIELD STRENGTH/SEQUENCE 3T/2D phase-contrast and time-resolved 4D flow MRI, extra- and transcranial sonography. ASSESSMENT Hemodynamics within the superficial and deep intracranial venous system and outflow tract including the internal, basal, and great cerebral vein, straight, superior sagittal, and transverse sinuses, internal jugular and vertebral veins. Sonography adhered to the chronic cerebrospinal venous insufficiency (CCSVI) criteria. STATISTICAL TESTS Multivariate repeated measure analysis of variance, Student's two-sample t-test, chi-square, Fisher's exact test; separate analysis of the entire cohort and 32 age- and sex-matched participants. RESULTS Multi- and univariate main effects of the factor group (MS patient vs. control) and its interactions with the factor vessel position (lower flow within dorsal superior sagittal sinus in MS, 3 ± 1 ml/s vs. 3.8 ± 1 ml/s; P < 0.05) in the uncontrolled cohort were attributable to age-related differences. Age- and sex-matched pairs showed a different velocity gradient in a single segment within the deep cerebral veins (great cerebral vein, vena cerebri magna [VCM] 7.6 ± 1.7 cm/s; straight sinus [StS] 10.5 ± 2.2 cm/s vs. volunteers: VCM 9.2 ± 2.3 cm/s; StS 10.2 ± 2.3 cm/s; P = 0.01), reaching comparable velocities instantaneously downstream. Sonography was not statistically different between groups. DATA CONCLUSION Consistent with previous studies focusing on extracranial hemodynamics, our comprehensive analysis of intracerebral venous blood flow did not reveal relevant differences between MS patients and controls. Level of Evidence 1. Technical Efficacy Stage 3. J. Magn. Reson. Imaging 2020;51:205-217.

BACKGROUND Aortic stiffness is associated with a higher incidence of cardiovascular events including stroke. The primary aim of this study was to evaluate whether increased pulse wave velocity (PWV), a marker of stiffness, is an independent predictor of aortic atheroma. The secondary aim was to test whether increased PWV reinforces retrograde blood flow from the descending aorta (DAo), a mechanism of stroke. METHODS We performed a cross-sectional case-control study with prospective data acquisition. In all, 40 stroke and 60 ophthalmic patients matched for age and cardiovascular risk factors were included. Multicontrast magnetic resonance imaging (MRI) protocol of the aorta tailored to allow a detailed plaque analysis using 3-dimensional (D) T1-weighted bright blood, T2-weighted and proton density-weighted black blood, and hemodynamic assessment using 4D flow MRI was applied. Individual PWV was calculated based on 4D flow MRI data using the time-to-foot of the blood flow waveform. The extent of maximum retrograde blood flow from the proximal DAo into the arch was quantified. RESULTS PWV was higher in stroke patients compared with controls (7.62±2.59 vs. 5.96±2.49 m/s; P=0.005) and in patients with plaques (irrespective of thickness) compared with patients without plaques (7.47±2.89 vs. 5.62±1.89 m/s; P=0.002). Increased PWV was an independent predictor of plaque prevalence and contributed significantly to a predictor model explaining 36.5% (Nagelkerke R2) of the variance in plaque presence. Maximum retrograde flow extent from the proximal DAo was not correlated with PWV. CONCLUSIONS Aortic stiffness was higher in stroke patients and associated with a higher prevalence of plaques. Increased PWV was an independent predictor of plaque presence. Accordingly, regional PWV seems to be a valuable biomarker for the assessment and management of aortic atherosclerosis. However, no association was found for increased retrograde flow extent from the DAo.

The underlying etiology of ischemic stroke remains unknown in up to 30% of patients.Objectives: This study explored the causal role of complicated (American Heart Association-lesion type VI) nonstenosing carotid artery plaques (CAPs) in cryptogenic stroke (CS).Methods: CAPIAS (Carotid Plaque Imaging in Acute Stroke) is an observational multicenter study that prospectively recruited patients aged older than 49 years with acute ischemic stroke that was restricted to the territory of a single carotid artery on brain magnetic resonance imaging (MRI) and unilateral or bilateral CAP (≥2 mm, NASCET [North American Symptomatic Carotid Endarterectomy Trial]

Es existieren mehrere automatische Analyseverfahren mit der Zielsetzung, mittels einer multimodalen CT- oder MRT-Bildgebung den thromboembolischen Gefasverschluss, den Infarktkern und das potenziell infarktgefahrdete Gewebe („tissue at risk“) darzustellen. Der Infarktkern wird mit DWI-MRT oder CT-Perfusion zuverlassiger als mit der nativen CT dargestellt. Die „Tissue-at-risk“-Ausdehnung und -Gefahrdung kann nur abgeschatzt werden. Wesentlich erscheint aber, ob uberhaupt „tissue at risk“ vorliegt. Um eine einheitliche Patientenversorgung zu gewahrleisten, sollten einheitliche Bildgebungsprotokolle im zuweisenden und Thrombektomie-Krankenhaus akquiriert und die erhobenen Daten standardisiert und automatisiert ausgewertet und dargestellt werden. Ob Patienten mit grosem Infarktkern und mit oder ohne „tissue at risk“ oder Patienten mit grosen Gefasverschlussen, aber niedrigem NIHSS von der Thrombektomie profitieren, muss mithilfe standardisierter Bildgebung in kontrollierten klinischen Studien uberpruft werden. Ein vielversprechender Ansatz ist auch, ein natives CT und CT-Angiogramm mit der Beurteilung des Gefasverschlusses und der leptomeningealen Kollateralen mit einer Flachdetektor-Angiographie-Anlage zu erstellen.

To quantify stiffness of the descending aorta (DAo) in stroke patients using 4D flow MRI and compare results with transesophageal echocardiography (TEE). 48 acute stroke patients undergoing 4D flow MRI and TEE were included. Intima-media-thickness (IMT) was measured in the DAo and the aorta was scrutinized for atherosclerotic plaques using TEE. Stiffness of the DAo was determined by (a) 4D flow MRI at 3 T by calculating pulse wave velocity (PWV) and by (b) TEE calculating arterial strain, stiffness index, and distensibility coefficient. Mean IMT was 1.43 ± 1.75. 7 (14.6%) subjects had no sign of atherosclerosis, 10 (20.8%) had IMT-thickening or plaques 4 mm. PWV and TEE parameters of stiffness correlated significantly [strain (r = − 0.36; p = 0.011), stiffness index (r = 0.51; p = 0.002), and distensibility coefficient (r = − 0.59; p

Background: Retrograde diastolic blood flow in the proximal descending aorta (DAo) connecting complex plaques (≥4 mm thick) with brain-supplying supra-aortic arteries may constitute a source of stroke. Yet, data only from high-risk populations (cryptogenic stroke patients with aortic atheroma ≥3 mm) regarding the prevalence of this potential stroke mechanism are available. We aimed to quantify the frequency of this mechanism in unselected patients with cryptogenic stroke after routine diagnostics and controls without a history of stroke. Methods: 88 patients (67 stroke patients, 21 cardiac controls) were prospectively included. 3D T1-weighted bright blood MRI of the aorta was applied for the detection of complex DAo atheroma. ECG-triggered and navigator-gated 4D flow MRI allowed measuring time-resolved 3D blood flow in vivo. Potential retrograde embolization pathways were defined as the co-occurrence of complex plaques and retrograde blood flow in the DAo reaching the outlet of (a) the left subclavian artery, (b) the left common carotid artery, or/and (c) the brachiocephalic trunk. The frequency of these pathways was analyzed by importing 2D plaque images into 3D blood flow visualization software. Results: Complex DAo plaques were more frequent in stroke patients (44 in 31/67 patients (46.3%) vs. 5 in 4/21 controls (19.1%); p = 0.039), especially in older patients (29/46 (63.04%) patients ≥60 years of age with 41 plaques vs. 2/21 (9.14%) patients Conclusions: This study revealed that retrograde flow in the descending aorta is a common phenomenon not only in stroke patients. The existence of potential retrograde embolization pathways depends mainly on the occurrence of complex plaques in the area 0 to ∼30 mm behind the outlet of the left subclavian artery, which is exposed to flow reversal. In conclusion, we have shown that the frequency of potential retrograde embolization pathways was significantly higher in stroke patients suggesting that this mechanism may play a role in retrograde brain embolism.

Objectives To develop a 3D-multi-contrast MRI protocol allowing for high resolution imaging of the wall and of atheroma in the thoracic aorta. Methods Eleven healthy volunteers and eleven acute stroke patients with aortic plaques detected by TEE underwent MRI at 3 T. The MRI-protocol consisted of a T1w-bright-blood, a T2w- and a PDw-black-blood sequence (spatial resolution = 1.15 mm3). Image quality was assessed by two blinded investigators using a 3-point score and intra- and inter-rater agreement was tested. In patients, atherosclerotic plaques were graded according to the modified American Heart Association (AHA) classification. Results Total examination time was 35:42 ± 7:48 min in volunteers and 41:07 ± 3:15 min in patients. Image quality was graded with the highest score in 80–94% of T1w, 89–96% of T2w and 79–86% of PDw datasets. Intra- and inter-rater reliability regarding image quality grading was high. Five stroke patients showed AHA type III lesions, three had AHA type VII and two had type VIII plaques. One patient had a vulnerable appearing AHA VI plaque. Conclusions 3D-multi-contrast MR-imaging of the aorta was performed with high image quality and in reasonable time. It allows evaluation of atherosclerotic plaque composition throughout the aortic arch and can be used to identify vulnerable plaques in acute stroke patients.

Purpose: To measure aortic pulse wave velocity (PWV) using flow-sensitive four-dimensional (4D) MRI and to evaluate test–retest reliability, inter- and intra-observer variability in volunteers and correlation with characteristics in patients with aortic atherosclerosis. Materials and Methods: Flow-sensitive 4D MRI was performed in 12 volunteers (24 ± 3 years) and 86 acute stroke patients (68 ± 9 years) with aortic atherosclerosis. Retrospectively positioned 28 ± 4 analysis planes along the entire aorta (inter-slice-distance = 10 mm) and frame wise lumen segmentation yielded flow-time-curves for each plane. Global aortic PWV was calculated from time-shifts and distances between the upslope portions of all available flow-time curves. Results: Inter- and intra-observer variability of PWV measurements in volunteers (7% and 8%) was low while test–retest reliability (22%) was moderate. PWV in patients was significantly higher compared with volunteers (5.8 ± 2.9 versus 3.8 ± 0.8 m/s; P = 0.02). Among 17 patient characteristics considered, statistical analysis revealed significant (P < 0.05) but low correlation of PWV with age (r = 0.25), aortic valve insufficiency (r = 0.29), and pulse pressure (r = 0.28). Multivariate modeling indicated that aortic valve insufficiency and elevated pulse pressure were significantly associated with higher PWV (adjusted R2 = 0.13). Conclusion: Flow-sensitive 4D MRI allows for estimating aortic PWV with low observer dependence and moderate test–retest reliability. PWV in patients correlated with age, aortic valve insufficiency, and pulse pressure. J. Magn. Reson. Imaging 2012;35:1162-1168. © 2012 Wiley Periodicals, Inc.

Background and Purpose— We hypothesized that for the prediction or exclusion of aortic thrombi or plaques ≥4 mm, the combination of intima-media thickness (IMT) and distensibility (DC) of the common carotid arteries would be superior to the measurement of IMT alone. Methods— We prospectively included 208 stroke patients (mean age, 60 years) undergoing transesophageal echocardiography for screening of aortic plaques. IMT and DC were determined by ultrasound, and DC was quantified by measuring blood pressure and the common carotid arteries diameter change on M-mode ultrasound during the cardiac cycle. Results— Negative predictive values of IMT −3 /kPa for the exclusion of aortic atheroma ≥4 mm were similar (92.0% and 91.7%, respectively). However, negative predictive values increased to 98.2% and to 100.0% for the exclusion of aortic thrombi when both parameters were combined. Positive predictive values of IMT ≥0.9 mm and DC Conclusions— Our findings suggest that IMT and DC represent different vessel wall properties and that measuring both parameters provides optimized characterization of carotid atherosclerosis. Combining IMT and DC increases the predictive power of carotid ultrasound, making transesophageal echocardiography dispensable for assessment of the aorta for those with normal carotid arteries and indispensable for those patients with carotid atherosclerosis.

BACKGROUND AND PURPOSE: 4D flow MR imaging is an emerging technique that allows visualization and quantification of 3D blood flow in vivo. However, representative studies evaluating its accuracy are lacking. Therefore, we compared blood flow quantification by using 4D flow MR imaging with US within the carotid bifurcation. MATERIALS AND METHODS: Thirty-two healthy volunteers (age 25.3 ± 3.4 years) and 20 patients with ≥50% ICA stenosis (age 67.7 ± 7.4 years) were examined preoperatively and postoperatively by use of 4D flow MR imaging, with complete coverage of the left and right carotid bifurcation. Blood flow velocities were assessed with standardized 2D analysis planes distributed along the CCA and the ICA and were compared with US at baseline and postoperatively in patients. In addition, we tested reproducibility and interobserver agreement of 4D MR imaging in 10 volunteers. RESULTS: Overall, 101 CCAs and 79 ICAs were available for comparison. MR imaging underestimated (P < .05) systolic CCA and ICA blood flow velocity by 26% (0.79 ± 0.29 m/s vs 1.06 ± 0.31 m/s) and 19% (0.72 ± 0.21 m/s vs 0.89 ± 0.27 m/s) compared with US. Diastolic blood flow velocities were similar for MR imaging and US (differences, 9% and 3%, respectively; not significant). Reproducibility and interobserver agreement of 4D flow MR imaging was excellent. CONCLUSIONS: 4D flow MR imaging allowed for an accurate measurement of blood flow velocities in the carotid bifurcation of both volunteers and patients with only moderate underestimation compared with US. Thus, 4D flow MR imaging seems promising for a future combination with MRA to comprehensively assess ICA stenosis and related hemodynamic changes.

Purpose: To evaluate the effect of field strength on flow-sensitive 4D magnetic resonance imaging (MRI) of the thoracic aorta. A volunteer study at 1.5 T and 3 T was conducted to compare phase-contrast MR angiography (MRA) and 3D flow visualization quality as well as quantification of aortic hemodynamics. Materials and Methods: Ten healthy volunteers were examined by flow-sensitive 4D MRI at both 1.5 T and 3 T MRI with identical imaging parameters (TE/TR = 6/5.1 msec, spatial/temporal resolution ≈2 mm/40.8 msec). Analysis included assessment of image quality of derived aortic 3D phase contrast (PC) angiography and 3D flow visualization (semiquantitative grading on a 0–2 scale, two blinded observers) and quantification of blood flow velocities, net flow per cardiac cycle, wall shear stress (WSS), and velocity noise. Results: Quality of 3D blood flow visualization (average grading = 1.8 ± 0.4 at 3 T vs. 1.1 ± 0.7 at 1.5 T) and the depiction of aortic lumen geometry by 3D PC-MRA (1.7 ± 0.5 vs. 1.2 ± 0.6) were significantly (P < 0.01) improved at 3 T while velocity noise was significantly higher (P < 0.01) at 1.5 T. Velocity quantification resulted in minimally altered (0.05 m/s, 3 mL/cycle and 0.01 N/m2) but not statistically different (P = 0.40, P = 0.39, and P = 0.82) systolic peak velocities, net flow, and WSS for 1.5 T compared to 3 T. Conclusion: Flow-sensitive 4D MRI at 3 T provided improved image quality without additional artifacts related to higher fields. Imaging at 1.5 T MRI, which is more widely available, was also feasible and provided information on aortic 3D hemodynamics of moderate quality with identical performance regarding quantitative analysis. J. Magn. Reson. Imaging 2012;36:1097–1103. © 2012 Wiley Periodicals, Inc.

Background— The purpose of this study was to analyze the in vivo distribution of absolute wall shear stress (WSS abs ) and oscillatory shear index (OSI) in the carotid bifurcation and to evaluate its dependence on bifurcation geometry, the presence of internal carotid artery (ICA) stenosis, and recanalization therapy. Methods and Results— Time-resolved 3D blood flow was acquired with flow-sensitive 4D MRI in 64 normal carotid bifurcations and 17 carotid arteries with moderate ICA stenosis (48±6%) or after surgical recanalization. Among 64 normal arteries, atherogenic wall parameters were consistently concentrated in proximal bulb regions of the common (CCA) and internal (ICA) carotid arteries. The fraction of the carotid bulb exposed to atherosclerosis-prone wall parameters (low WSS abs below and high OSI above group-defined 20% and 10% thresholds) was correlated with the individual bifurcation geometry. Multiple regressions revealed significant ( P ICA /d CCA diameter ratio. The size of regions exposed to high OSI demonstrated highly significant ( P ≤0.01) relationships with all analyzed geometry parameters (d ICA /d CCA β, 0.48; tortuosity β, ≤−0.56; bifurcation angle β, ≥0.47). Moderate ICA stenosis altered the distribution of wall parameters (45%/61% reduction of individually low WSS abs /high OSI in the proximal ICA), which were relocated to segments distal to the arterial stenosis. WSS abs /OSI topology after recanalization was similar compared with the normal wall parameter distribution. Conclusions— Flow-sensitive 4D MRI identified alterations in the segmental in vivo WSS distribution associated with atherosclerotic disease, surgical therapy, and individual bifurcation geometry and could be a valuable technique to assess the individual risk of flow-mediated atherosclerosis and carotid plaque progression.

Background and Purpose— To investigate the incidence of retrograde flow from complex plaques (≥4-mm-thick, ulcerated, or superimposed thrombi) of the descending aorta (DAo) and its potential role in embolic stroke. Methods— Ninety-four consecutive acute stroke patients with aortic plaques ≥3-mm-thick in transesophageal echocardiography were prospectively included. MRI was performed to localize complex plaques and to measure time-resolved 3-dimensional blood flow within the aorta. Three-dimensional visualization was used to evaluate if diastolic retrograde flow connected plaque location with the outlet of the left subclavian artery, left common carotid artery, or brachiocephalic trunk. Complex DAo plaques were considered an embolic source if retrograde flow reached a supra-aortic vessel that supplied the territory of visible acute and embolic retinal or cerebral infarction. Results— Only decreasing heart rate was correlated (P Conclusions— Retrograde flow from complex DAo plaques was frequent in both determined and cryptogenic stroke and could explain embolism to all brain territories. These findings suggest that complex DAo plaques should be considered a new source of stroke.

Background and Purpose— The purpose of this study was to determine the role of plaques ≥4 mm and thrombi (complex plaques) in the descending aorta (DAo) as an embolic high-risk source for stroke. Methods— In 63 acute stroke patients scheduled for TEE, territory and embolic pattern of brain ischemia were prospectively assessed. Multidirectional 3D MRI velocity mapping of the aorta was performed to correlate the extent of retrograde diastolic blood flow with the distance of complex DAo plaques from the left subclavian artery (LSA). Embolic risk from the DAo was present for (1) retrograde flow connecting complex DAo plaques with the LSA, (2) embolic pattern of brain ischemia in a territory supplied by the left vertebral artery, and (3) stroke that could not be explained by other means. Results— 33 of 63 patients had complex DAo plaques (distance to LSA 28.1±29.9 mm). Mean retrograde flow in these subjects was 26.2±12.3 mm. In 20 of 63 patients (31.7%) retrograde flow connected complex DAo plaques with the LSA. In 4 of these 20 patients (20%) with an embolic stroke in the territory of the brain stem, cerebellum or posterior cerebral artery, etiology could not be explained by other means. Conclusions— Substantial diastolic retrograde flow originating from complex plaques in the descending aorta was detected by multidirectional 3D MRI velocity mapping and constitutes a stroke mechanism that was previously not demonstrable.

The combination of morphologic and hemodynamic information can help in assessing the risk of embolic stroke associated with thrombi and plaques in the descending aorta. For two acute stroke patients, the determination of individual embolic pathways using flow-sensitive four-dimensional (4D) MRI are reported. 3D visualization of local flow patterns, i.e., retrograde flow channels originating at the site of the atheroma, in conjunction with exact plaque localization, suggested potential embolization of high-risk plaques in the descending aorta although they are located downstream from the supraaortic arteries. Our findings indicate that taking plaques of the descending aorta into consideration may help improve the spectrum of pathologies considered as high-risk sources for brain ischemia. J. Magn. Reson. Imaging 2007. © 2007 Wiley-Liss, Inc.

Objectives: To evaluate a new three dimensional (3D) MRI protocol for the reliable detection of aortic high risk plaques compared with transoesophageal echocardiography (TOE) and to test the reliability of additional MRI in stroke of undetermined aetiology. Methods: 74 acute stroke patients were examined by both TOE and MRI at 3 Tesla with special regard to aortic high risk plaques (ie, ⩾4 mm, superimposed thrombi). ECG synchronised pre- and post-contrast T1 weighted 3D imaging (spatial resolution ∼1 mm3) covering the thoracic aorta was employed. In plaques ⩾3 mm, additional two dimensional T2 imaging and time resolved (CINE) imaging sequences were performed. Aetiology of brain ischaemia was classified according to modified TOAST (Trial of Org 10172 in Acute Stroke Treatment) criteria. Aortic high risk embolic sources detected by MRI in patients with cryptogenic stroke were evaluated. Results: Differences in maximum aortic wall thickness for TOE and MRI were not statistically significant for all aortic segments. The overall number of high risk plaques detected by MRI (n = 74) was substantially higher compared with TOE (n = 47). Most noticeably, MRI identified aortic high risk pathologies in 8/26 (30.8%) patients with cryptogenic stroke after standard diagnostics, including TOE (n = 2: dissection or thrombus; n = 6: plaques ⩾4 mm). Conclusions: Our results demonstrate the feasibility of this 3D MRI protocol for the reliable detection of aortic high risk plaques in acute stroke patients. Because of improved visualisation of the aortic arch and the detection of additional embolic sources not seen by standard diagnostics, this novel technique may become a valuable tool for future patients with cryptogenic stroke.

Purpose To evaluate the feasibility of an optimized bright blood MRI protocol at 3 T in combination with contrast agent administration for the detection and characterization of aortic high-risk plaques for the improved workup of acute stroke patients. Materials and Methods ECG synchronized T1-weighted 3D gradient echo MRI was performed in 45 acute stroke patients. Data were acquired with high near isotropic spatial resolution (∼1 mm3) covering the entire thoracic aorta. To compensate for breathing and vessel motion artifacts, images were collected using respiratory navigator gating in combination with short diastolic data acquisition windows adjusted on a patient-by-patient basis. In patients with aortic plaques ≥3 mm in thickness, gadolinium contrast agent was administered and both pre- and post-contrast T1-weighted 3D measurements with identical vessel coverage were performed. Results Bright blood 3D MRI detected 33 high-risk plaques with an average maximum plaque thickness of 4.2±1.0 mm in 23 of 45 acute stroke patients. The availability of pre- and post-contrast images acquired within the same session enhanced the identification of calcified plaque components in 77% of all analyzed plaques: post-contrast MRI clearly improved the delineation of hypointense plaque cores in 23 of 30 cases and assisted in the classification of core shape and of core fraction. Conclusion 3D bright blood MRI at 3 T was feasible for the detection of aortic high-risk sources and may help to improve the detection of causes of cerebral embolism in acute stroke patients.

Unser Beitrag befast sich mit einer Untersuchung, die das Institut fur Rechtstatsachenforschung Stuttgart e.V. (1)* im Auftrag des Justizministeriums der Bundesrepublik Deutschland zur Zeit durchfuhrt. Bevor wir zu den einzelnen Arbeitshypothesen kommen, wollen wir versuchen, unser Forschungsvorhaben in den Bezugsrahmen einer idealtypischen Beschreibung der staatlichen Justiz zu stellen, sowie einige Theorien „mittlerer Reichweite“ zum gerichtlichen Verfahren diskutieren.