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Association between clinical factors and high-risk plaque features, such as, thin or ruptured cap, intraplaque hemorrhage, presence of lipid-rich necrotic core (LRNC), and increased LRNC volume as assessed by magnetic resonance imaging (MRI), was examined in patients with established vascular disease in the Atherothrombosis Intervention in Metabolic Syndrome With Low HDL/High Triglycerides (AIM-HIGH) trial. A total of 214 subjects underwent carotid MRI and had acceptable image quality for assessment of plaque burden, tissue contents, and MRI-modified American Heart Association lesion type by a core laboratory. We found that 77% of subjects had carotid plaques, 52% had lipid-containing plaques, and 11% had advanced American Heart Association type-VI lesions with possible surface defect, intraplaque hemorrhage, or mural thrombus. Type-VI lesions were associated with older age (odds ratio [OR] = 2.6 per 5 years increase, p <0.001). After adjusting for age, these lesions were associated with history of cerebrovascular disease (OR = 4.1, p = 0.01), higher levels of lipoprotein(a) (OR = 2.0 per 1 SD increase, p = 0.02), and larger percent wall volume (PWV [OR = 4.6 per 1 SD increase, p <0.001]) but, were negatively associated with metabolic syndrome (OR = 0.2, p = 0.02). Presence of LRNC was associated with the male gender (OR = 3.2, p = 0.02) and PWV (OR = 3.8 per 1 SD, p <0.001); however, it was negatively associated with diabetes (OR = 0.4, p = 0.02) and high-density lipoprotein cholesterol levels (OR = 0.7 per 1 SD, p = 0.02). Increased percent LRNC was associated with PWV (regression coefficient = 0.36, p <0.001) andnegatively associated with ApoA1 levels (regression coefficient = --0.20, p = 0.03). In conclusion, older age, male gender, history of cerebrovascular disease, larger plaque burden, higher lipoprotein(a), and lower high-density lipoprotein cholesterol or ApoA1 level have statistically significant associations with high-risk plaque features. Metabolic syndrome and diabetes showed negative associations in this population. [ABSTRACT FROM AUTHOR]

Alterations in cerebral vasculature are instrumental in affecting cognition. Current studies mainly focus on proximal large arteries and small vessels, while disregarding morphology and blood flow of the arteries between them (medium-to-large arteries). In this prospective study, two types of non-contrast enhanced magnetic resonance angiography (NCE-MRA) techniques, simultaneous non-contrast angiography and intraplaque hemorrhage (SNAP) and 3D Time-of-flight (TOF), were used to measure vascular morphologic features in medium-to-large intracranial arteries. Grey matter (GM) tissue level perfusion was assessed with arterial spin labeling (ASL) MRI. Twenty-seven subjects at high cardiovascular risk underwent baseline and 12-month follow-up MRI to compare the relationship between morphological features measured by NCE MRA, GM CBF by ASL MRI, and cognitive function measured by the Montreal Cognitive Assessment (MoCA). Changes in both global medium-to-large arteries and posterior cerebral (PCA) distal artery length and branch numbers, measured on SNAP MRA, were significantly associated with alterations in MoCA scores (P < 0.01), after adjusting for clinical confounding factors, total brain volume, and total white matter lesion (WML) volume. There were no associations between MoCA scores and vascular features on TOF MRA or ASL GM CBF. Alterations in vascular features of distal medium-to-large arteries may be more sensitive for detecting potential changes in cognition than cerebral blood flow alterations at the parenchymal level captured by perfusion ASL. Hemodynamic information from distal medium-to-large arteries provides an additional tool to advance understanding of the vascular contributions to cognitive function. [ABSTRACT FROM AUTHOR]

Developing novel risk markers for vascular contributions to cognitive impairment and dementia is important. This study aimed to extract total length, branch number and average tortuosity of intracranial distal arteries (A2, M2, P2 and more distal) from non-contrast enhanced magnetic resonance angiography (NCE-MRA) images, and explore their associations with global cognition. In 29 subjects (aged 40–90 years) with carotid atherosclerotic disease, the 3 intracranial vascular features on two NCE-MRA techniques (i.e. time of flight, TOF and simultaneous non-contrast angiography and intraplaque hemorrhage, SNAP) were extracted using a custom-developed software named iCafe. Arterial spin labeling (ASL) and phase contrast (PC) cerebral blood flow (CBF) were measured as references. Linear regression was performed to study their associations with global cognition, measured with the Montreal Cognitive Assessment (MoCA). Intracranial artery length and number of branches on NCE-MRA, ASL CBF and PC CBF were found to be positively associated with MoCA scores (P < 0.01). The associations remained significant for artery length and number of branches on NCE-MRA after adjusting for clinical covariates and white matter hyperintensity volume. Further adjustment of confounding factors of ASL CBF or PC CBF did not abolish the significant association for artery length and number of branches on TOF. Our findings suggest that intracranial vascular features, including artery length and number of branches, on NCE-MRA may be useful markers of cerebrovascular health and provide added information over conventional brain blood flow measurements in individuals with cognitive impairment. [ABSTRACT FROM AUTHOR]

Purpose: Dietary sodium and potassium intake are associated with stroke, but the potential mechanisms are unclear. We aimed to study the association between sodium and potassium intake and subclinical cerebrovascular health in hypertensive older males using multimodal magnetic resonance imaging. Methods: A total of 189 hypertensive male subjects without previous cardiovascular or cerebrovascular disease were included. Daily urinary sodium and potassium excretion were estimated from a fasting spot urine sample using a formula approach. A dedicated cerebrovascular health imaging protocol including vessel wall imaging, angiography, arterial spin labeling imaging and T2-weighted fluid-attenuated inversion recovery imaging was performed to study intracranial atherosclerosis, vascular rarefaction (defined as fewer discernible vessels on angiography), brain perfusion and small vessel disease, respectively. Results: The mean age was 64.9 (± 7.2) years. The average daily urinary and potassium excretion was 4.7 (± 1.4) g/L and 2.1 (± 0.5) g/L, respectively. Increased urinary sodium excretion was associated with decreased cerebral blood flow and elevated urinary potassium excretion was associated with reduced prevalence of intracranial plaque. The associations remained significant after adjusting for covariates, even including blood pressure control. Quadratic regression analysis indicated a marginally significant U-shaped association between urinary sodium intake and white matter hyperintensity, which lost significance in fully adjusted models. No significant association of urinary sodium and potassium excretion with other cerebrovascular health measures was noted. Conclusion: We concluded that in hypertensive older males without overt cardiovascular disease, increased sodium intake and reduced potassium intake are associated with impaired subclinical cerebrovascular health. [ABSTRACT FROM AUTHOR]

Proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors reduce cardiovascular events, but their effects on atherosclerotic plaque remain elusive. Using serial magnetic resonance imaging (MRI), we studied changes in carotid plaque lipid content and neovasculature under PCSK9 inhibition with alirocumab. Among patients with low-density lipoprotein cholesterol (LDL-C) ≥70 mg/dl but ineligible for high-dose statin therapy, those with lipid core on carotid MRI were identified to receive alirocumab 150 mg every 2 weeks. Follow-up MRI was performed at 3, 6, and 12 months after treatment. Pre- and post-contrast MRI were acquired to measure percent lipid core volume (% lipid core). Dynamic contrast-enhanced MRI was acquired to measure the extravasation rate of gadolinium contrast (K trans ), a marker of plaque neovasculature. Of 31 patients enrolled, 27 completed the study (mean age: 69 ± 9; male: 67%). From 9.8% at baseline, % lipid core was progressively reduced to 8.4% at 3 months, 7.5% at 6 months, and 7.2% at 12 months (p = 0.014 for trend), which was accompanied by a progressive increase in % fibrous tissue (p = 0.009) but not % calcification (p = 0.35). K trans was not reduced until 12 months (from 0.069 ± 0.019 min−1 to 0.058 ± 0.020 min−1; p = 0.029). Lumen and wall areas did not change significantly during the study period. Regression in plaque composition and neovasculature were observed under PCSK9 inhibition on carotid MRI, which provides unique insight into the biological process of plaque stabilization with disease-modifying therapies. [Display omitted] • Carotid MRI can quantify plaque lipid content (% lipid core) and neovasculature (K trans ). • With PCSK9i, % lipid core was reduced progressively and seen as early as 3 months. • K trans , a marker of plaque neovasculature, was not reduced until 1 year. • Changes in serum lipids and imaging markers did not correlate at the individual level. [ABSTRACT FROM AUTHOR]

Vascular dysfunctions, including arterial stiffness and endothelial dysfunction, are prevalent in hypertensive subjects. We aimed to study their relations to subclinical intracranial vascular health in this study. A total of 200 older hypertensive males without overt cardiovascular or cerebrovascular diseases were recruited. Arterial elasticity was measured as carotid-femoral pulse wave velocity (cfPWV) and endothelial function was measured as digital reactive hyperemia index (RHI). Cerebrovascular health was evaluated using MRI in four aspects: intracranial atherosclerosis, brain perfusion as cerebral blood flow (CBF), vascular rarefaction analyzed as visible arterial branches on angiography using a custom-developed analysis technique and small vessel disease measured as white matter hyperintensity (WMH). There was a significant negative association between cfPWV and CBF, suggesting a link between arterial stiffness and CBF decline. Higher cfPWV was also associated with presence of intracranial stenotic plaque and greater WMH volume. RHI was positively related to CBF, indicating that endothelial dysfunction was associated with reduced CBF. All the associations remained significant after adjustment for confounding variables. Arterial stiffness and endothelial dysfunction are associated with reduced brain perfusion in older hypertensive males. Arterial stiffness is also associated with global cerebral vascular injury, affecting both small and medium-to-large arteries. [ABSTRACT FROM AUTHOR]

Objectives: The study aimed to analyze the association between hypertension control and subclinical cerebrovascular health using a comprehensive multimodal imaging approach. Methods: The study included 200 hypertensive older males without previous cardiovascular diseases. Clinic blood pressure (BP) was measured using a standard approach. Cerebrovascular health was evaluated using magnetic resonance imaging in the following four aspects: Intracranial atherosclerosis as determined by vessel wall imaging; Vascular rarefaction (defined as less discernible vessels on angiography) was evaluated using a custom-developed technique. Cerebral blood flow (CBF) and white matter hyperintensity (WMH) were assessed using arterial spin-labeling imaging and fluid-attenuated inversion recovery imaging, respectively. Results: A total of 189 subjects had MRI scans. The mean age was 64.9 (± 7.2) years. For intracranial atherosclerosis, there was a significant association between uncontrolled hypertension and presence of intracranial plaque. When systolic and diastolic BP were analyzed separately, the association remained significant for both. For vascular rarefaction, uncontrolled hypertension was associated with less discernible vessel branches or shorter vessel length on angiography. Further analysis revealed that this is due to uncontrolled diastolic BP, but not uncontrolled systolic BP. There was an association between uncontrolled hypertension and reduced CBF, which was also mainly driven by uncontrolled diastolic BP. We also found that uncontrolled diastolic BP, but not uncontrolled systolic BP, was associated with increased WMH volume. Conclusions: Uncontrolled hypertension was associated with subclinical cerebrovascular injury globally, with both small and medium-to-large arteries being affected. Key Points: • In this study, we leveraged the advantage of a series of cutting-edge MR imaging and analysis techniques and found uncontrolled hypertension is associated with subclinical globally compromised cerebrovascular health. • The detrimental consequences of uncontrolled BP affect not only the small vessels but also the medium-to-large arteries, and uncontrolled systolic and diastolic BP are both independently associated with certain types of cerebrovascular injury. • Our data suggest that cerebrovascular health is impaired globally in uncontrolled hypertension before the onset of stroke. [ABSTRACT FROM AUTHOR]

Background: In the last 20–30 years, there have been many advances in imaging and therapeutic strategies for symptomatic and asymptomatic individuals with carotid artery stenosis. Our aim was to examine contemporary multinational practice standards. Methods: Departmental Review Board approval for this study was obtained, and 3 authors prepared the 44 multiple choice survey questions. Endorsement was obtained by the European Society of Neuroradiology, American Society of Functional Neuroradiology, and African Academy of Neurology. A link to the online questionnaire was sent to their respective members and members of the Faculty Advocating Collaborative and Thoughtful Carotid Artery Treatments (FACTCATS). The questionnaire was open from May 16 to July 16, 2019. Results: The responses from 223 respondents from 46 countries were included in the analyses including 65.9% from academic university hospitals. Neuroradiologists/radiologists comprised 68.2% of respondents, followed by neurologists (15%) and vascular surgeons (12.9%). In symptomatic patients, half (50.4%) the respondents answered that the first exam they used to evaluate carotid bifurcation was ultrasound, followed by computed tomography angiography (CTA, 41.6%) and then magnetic resonance imaging (MRI 8%). In asymptomatic patients, the first exam used to evaluate carotid bifurcation was ultrasound in 88.8% of respondents, CTA in 7%, and MRA in 4.2%. The percent stenosis upon which carotid endarterectomy or stenting was recommended was reduced in the presence of imaging evidence of "vulnerable plaque features" by 66.7% respondents for symptomatic patients and 34.2% for asymptomatic patients with a smaller subset of respondents even offering procedural intervention to patients with <50% symptomatic or asymptomatic stenosis. Conclusions: We found heterogeneity in current practices of carotid stenosis imaging and management in this worldwide survey with many respondents including vulnerable plaque imaging into their decision analysis despite the lack of proven benefit from clinical trials. This study highlights the need for new clinical trials using vulnerable plaque imaging to select high-risk patients despite maximal medical therapy who may benefit from procedural intervention. [ABSTRACT FROM AUTHOR]

To characterize the intracranial vascular features extracted from time of flight (TOF) images and their changes from baseline to follow-up in patients undergoing carotid revascularization, using arterial spin labeling (ASL) cerebral blood flow (CBF) measurement as a reference. In this retrospective study, brain TOF and ASL images of 99 subjects, acquired before, within 48 h, and/or 6 months after, carotid revascularization surgery were analyzed. TOF images were analyzed using a custom software (iCafe) to quantify intracranial vascular features, including total vessel length, total vessel volume, and number of branches. Mean whole-brain CBF was calculated from ASL images. ASL scans showing low ASL signal in the entire flow territory of an internal carotid artery (ICA), which may be caused by labeling failure, were excluded. Changes and correlations between time points were analyzed separately for TOF intracranial vascular features and ASL CBF. Similar to ASL CBF, TOF vascular features (i.e. total vessel length, total vessel volume and number of branches) increased dramatically from baseline to post-surgery, then returned to a level slightly higher than the baseline in long-term follow-up (All P < 0.05). Correlation between time points was observed for all three TOF vascular features but not for ASL CBF. Intracranial vascular features, including total vessel length, total vessel volume and number of branches, extracted from TOF images are useful in detecting brain blood flow changes induced by carotid revascularization surgery. [ABSTRACT FROM AUTHOR]

BACKGROUND: Carotid atherosclerotic plaque with the length of about 3 cm completely embedding into paraffin block is a key step.OBJECTIVE: To clarify a method to embed carotid atherosclerotic plaque en bloc in paraffin.METHODS: Carotid atherosclerotic plaque was removed from the carotid endanerectomy at Beijing Tiantan Hospital, Capital Medical University. In order to facilitate the comparison between histological slices from serial sectioning and MRI, we need to embed carotid atherosclerotic plaque en bloc in paraffin.RESULTS AND CONCLUSION: With the guidance of the University of Washington Vascular Imaging Lab, we had established a simple embedding method according to the practice in our lab. With the method, we successfully overcame the technical difficulties in the en bloc embedding of carotid atherosclerotic plaque, which provides a reference for researchers with similar work needs. [ABSTRACT FROM AUTHOR]

Plaque progression prediction is of fundamental significance to cardiovascular research and disease diagnosis, prevention, and treatment. Magnetic resonance image (MRI) data of carotid atherosclerotic plaques were acquired from 20 patients with consent obtained. 3D thin-layer models were constructed to calculate plaque stress and strain. Data for ten morphological and biomechanical risk factors were extracted for analysis. Wall thickness increase (WTI), plaque burden increase (PBI) and plaque area increase (PAI) were chosen as three measures for plaque progression. Generalized linear mixed models (GLMM) with 5-fold cross-validation strategy were used to calculate prediction accuracy and identify optimal predictor. The optimal predictor for PBI was the combination of lumen area (LA), plaque area (PA), lipid percent (LP), wall thickness (WT), maximum plaque wall stress (MPWS) and maximum plaque wall strain (MPWSn) with prediction accuracy = 1.4146 (area under the receiver operating characteristic curve (AUC) value is 0.7158), while PA, plaque burden (PB), WT, LP, minimum cap thickness, MPWS and MPWSn was the best for WTI (accuracy = 1.3140, AUC = 0.6552), and a combination of PA, PB, WT, MPWS, MPWSn and average plaque wall strain (APWSn) was the best for PAI with prediction accuracy = 1.3025 (AUC = 0.6657). The combinational predictors improved prediction accuracy by 9.95%, 4.01% and 1.96% over the best single predictors for PAI, PBI and WTI (AUC values improved by 9.78%, 9.45%, and 2.14%), respectively. This suggests that combining both morphological and biomechanical risk factors could lead to better patient screening strategies. • Combining morphological and mechanical factors can improve plaque progression prediction accuracy by 10%. • Plaque burden increase is more predictable than wall thickness increase and plaque area increase (progression measures). • 3D thin-layer model requires much less labor cost and correlation results were consistent with 3D full vessel models. [ABSTRACT FROM AUTHOR]

Comprehensive quantification of intracranial artery features may help us assess and understand variations of blood supply during brain development and aging. We analyzed vasculature features of 163 participants (age 56–85 years, mean of 71) from a community study to investigate if any of the features varied with age. Three-dimensional time-of-flight magnetic resonance angiography images of these participants were processed in IntraCranial artery feature extraction technique (a recently developed technique to obtain quantitative features of arteries) to divide intracranial vasculatures into anatomical segments and generate 8 morphometry and intensity features for each segment. Overall, increase in age was found negatively associated with number of branches and average order of intracranial arteries while positively associated with tortuosity, which remained after adjusting for cardiovascular risk factors. The associations with number of branches and average order were consistently found between 3 main intracranial artery regions, whereas the association with tortuosity appeared to be present only in middle cerebral artery/distal arteries. The combination of time-of-flight magnetic resonance angiography and IntraCranial artery feature extraction technique may provide an effective way to study vascular conditions and changes in the aging brain. • Increase in age was negatively associated with number of branches and average order. • Increase in age was positively associated with average tortuosity. • Vascular regions may have different age-related changes for some features. • Time-of-flight magnetic resonance angiography and IntraCranial artery feature extraction technique may provide a novel way to assess vascular condition and changes. [ABSTRACT FROM AUTHOR]

Stroke represents a massive public health problem. Carotid atherosclerosis plays a fundamental part in the occurence of ischaemic stroke. European and US guidelines for prevention of stroke in patients with carotid plaques are based on quantification of the percentage reduction in luminal diameter due to the atherosclerotic process to select the best therapeutic approach. However, better strategies for prevention of stroke are needed because some subtypes of carotid plaques (eg, vulnerable plaques) can predict the occurrence of stroke independent of the degree of stenosis. Advances in imaging techniques have enabled routine characterisation and detection of the features of carotid plaque vulnerability. Intraplaque haemorrhage is accepted by neurologists and radiologists as one of the features of vulnerable plaques, but other characteristics-eg, plaque volume, neovascularisation, and inflammation-are promising as biomarkers of carotid plaque vulnerability. These biomarkers could change current management strategies based merely on the degree of stenosis. [ABSTRACT FROM AUTHOR]

Abstract Background Accurate and reliable vascular features extracted from 3D time-of-flight (TOF) magnetic resonance angiography (MRA) can help evaluate cerebral vascular diseases and conditions. The goal of this study was to evaluate the reproducibility of an intracranial artery feature extraction (iCafe) algorithm for quantitative analysis of intracranial arteries from TOF MRA. Methods Twenty-four patients with known intracranial artery stenosis were recruited and underwent two separate MRA scans within 2 weeks of each other. Each dataset was blinded to associated imaging and clinical data and then processed independently using iCafe. Inter-scan reproducibility analysis was performed on the 24 pairs of scans while intra-/inter-operator reproducibility and stenosis detection were assessed on 8 individual MRA scans. After tracing the vessels visualized on TOF MRA, iCafe was used to automatically extract the locations with stenosis and eight other vascular features. The vascular features included the following six morphometry and two signal intensity features: artery length (total, distal, and proximal), volume, number of branches, average radius of the M1 segment of the middle cerebral artery, and average normalized intensity of all arteries and large vertical arteries. A neuroradiologist independently reviewed the images to identify locations of stenosis for the reference standard. Reproducibility of stenosis detection and vascular features was assessed using Cohen's kappa, the intra-class correlation coefficient (ICC), and within-subject coefficient of variation (CV). Results The segment-based sensitivity of iCafe for stenosis detection ranged from 83.3–91.7% while specificity was 97.4%. Kappa values for inter-scan and intra-operator reproducibility were 0.73 and 0.77, respectively. All vascular features demonstrated excellent inter-scan and intra-operator reproducibility (ICC = 0.91–1.00, and CV = 1.21–8.78% for all markers), and good to excellent inter-operator reproducibility (ICC = 0.76–0.99, and CV = 3.27–15.79% for all markers). Conclusion Intracranial artery features can be reliably quantified from TOF MRA using iCafe to provide both clinical diagnostic assistance and facilitate future investigative quantitative analyses. [ABSTRACT FROM AUTHOR]

Recent studies report that the rate of recurrent stroke is highest in the stages immediately following cerebral infarction and decreases over time in patients with atherosclerotic carotid stenosis. The purpose of this study was to identify temporal differences in early stage carotid plaque components from acute cerebrovascular ischemic events using carotid MRI. Carotid plaque images were obtained on 3 T MRI from 128 patients enrolled in MR-CAS. Among the 128 subjects, 53 were symptomatic and 75 asymptomatic. The symptomatic patients were classified into three groups based on interval from onset of symptoms to the date of the carotid MRI (Group <14 days; 15-30 days; and > 30 days). The volume of each plaque component was identified and quantified from MR images. The presence of juxtaluminal loose matrix/inflammation (LM/I) was identified as a possible indicator of inflammation on the luminal side. Plaque components were compared between groups using the Wilcoxon rank-sum or the Chi-square test. Patient characteristics and carotid plaque morphology were similar among all four groups. The median volume of LM/I in Group >30 days was significantly lower than in other groups (0 mm3 vs 12.3 mm3 and 18.1 mm3; p = 0.003). In addition, the prevalence of juxtaluminal LM/I decreased over time (ptrend = 0.002). There were no statistically significant differences in other plaque components between the symptomatic groups. The volume of LM/I was significantly smaller in Group >30 days and prevalence of juxtaluminal LM/I in the atherosclerotic carotid plaque was high in the early stages after events. This suggests that carotid plaques undergo rapid evolution after an acute cerebrovascular ischemic event. • MRI detected carotid plaque high T2W signal was less common as the time from onset of a carotid-territory ischemic event increased. • This phenomenon was observed more frequently on the lumen surface. • This result raises the possibility of change of carotid plaque composition after an acute cerebrovascular ischemic event. [ABSTRACT FROM AUTHOR]

Background: Image-based computational models are widely used to determine atherosclerotic plaque stress/strain conditions and investigate their association with plaque progression and rupture. However, patient-specific vessel material properties are in general lacking in those models, limiting the accuracy of their stress/strain measurements. A noninvasive approach of combining in vivo 3D multi-contrast and Cine magnetic resonance imaging (MRI) and computational modeling was introduced to quantify patient-specific carotid plaque material properties for potential plaque model improvements. Vessel material property variation in patients, along vessel segment, and between baseline and follow up were investigated. Methods: In vivo 3D multi-contrast and Cine MRI carotid plaque data were acquired from 8 patients with follow-up (18 months) with written informed consent obtained. 3D thin-layer models and an established iterative procedure were used to determine parameter values of the Mooney-Rivlin models for the 81slices from 16 plaque samples. Effective Young’s Modulus (YM) values were calculated for comparison and analysis. Results: Average Effective Young’s Modulus (YM) and circumferential shrinkage rate (C-Shrink) value of the 81 slices was 411kPa and 5.62%, respectively. Slice YM value varied from 70 kPa (softest) to 1284 kPa (stiffest), a 1734% difference. Average slice YM values by vessel varied from 109 kPa (softest) to 922 kPa (stiffest), a 746% difference. Location-wise, the maximum slice YM variation rate within a vessel was 311% (149 kPa vs. 613 kPa). The average slice YM variation rate for the 16 vessels was 134%. The average variation of YM values for all patients from baseline to follow up was 61.0%. The range of the variation of YM values was [-28.4%, 215%]. For plaque progression study, YM at follow-up showed negative correlation with plaque progression measured by wall thickness increase (WTI) (r = -0.7764, p = 0.0235). Wall thickness at baseline correlated with WTI negatively, with r = -0.5253 (p = 0.1813). Plaque burden at baseline correlated with YM change between baseline and follow-up, with r = 0.5939 (p = 0.1205). Conclusion: In vivo carotid vessel material properties have large variations from patient to patient, along the diseased segment within a patient, and with time. The use of patient-specific, location specific and time-specific material properties in plaque models could potentially improve the accuracy of model stress/strain calculations. [ABSTRACT FROM AUTHOR]

Background: Image registration is an important research topic in the field of image processing. Applying image registration to vascular image allows multiple images to be strengthened and fused, which has practical value in disease detection, clinical assisted therapy, etc. However, it is hard to register vascular structures with high noise and large difference in an efficient and effective method. Results: Different from common image registration methods based on area or features, which were sensitive to distortion and uncertainty in vascular structure, we proposed a novel registration method based on network structure and circuit simulation. Vessel images were transformed to graph networks and segmented to branches to reduce the calculation complexity. Weighted graph networks were then converted to circuits, in which node voltages of the circuit reflecting the vessel structures were used for node registration. The experiments in the two-dimensional and three-dimensional simulation and clinical image sets showed the success of our proposed method in registration. Conclusions: The proposed vascular image registration method based on network structure and circuit simulation is stable, fault tolerant and efficient, which is a useful complement to the current mainstream image registration methods. [ABSTRACT FROM AUTHOR]

Background and aims Prospective studies have shown a strong association between carotid intraplaque hemorrhage (IPH), detected by magnetic resonance imaging (MRI), and cerebrovascular ischemic events. However, IPH is also observed in a substantial number of asymptomatic patients. We hypothesized that there are differences in the characteristics of IPH+ plaques associated with recent symptoms, compared to IPH+ plaques not associated with recent symptoms. Methods Patients with recent (≤2 weeks) anterior circulation ischemic events were scanned using a standardized multisequence protocol. Those showing IPH bilaterally were included and analyzed for differences in T1/T2 signals, plaque morphology, and coexisting plaque characteristics between the ipsilateral symptomatic and contralateral asymptomatic sides. Results Thirty-one subjects (67 ± 9 years, 97% males) with bilateral IPH were studied. Despite comparable luminal stenosis (53 ± 42% vs. 53 ± 39%, p = 0.99), T1 signal of IPH measured as signal-intensity-ratio compared to muscle was stronger (SIR IPH-to-muscle : 5.8 ± 2.4 vs. 4.7 ± 1.8, p = 0.004) and tended to be more extensively distributed (IPH volume: 150 ± 199 vs. 88 ± 106 mm 3 , p = 0.071) on the symptomatic side. IPH+ plaques on the symptomatic side were longer (24 ± 6 vs. 21 ± 7 mm, p = 0.026) and associated with larger necrotic core volume (406 ± 354 vs. 291 ± 293 mm 3 , p = 0.039) than those on the asymptomatic side. Conclusions In recently symptomatic patients with bilateral carotid IPH, the symptomatic side showed stronger T1 signals, larger necrotic cores, and longer plaque length than the asymptomatic side. Serial studies on the temporal relationship between these imaging features and clinical events will eventually establish their diagnostic and prognostic value beyond the mere presence of IPH. [ABSTRACT FROM AUTHOR]

Background and aims Plaque fissuring, a phenomenon morphologically distinct from the classical rupture of a thinned fibrous cap, has not been well characterized in carotid atherosclerosis. The aim of this study was to establish the prevalence of plaque fissures in advanced carotid plaques with an otherwise intact luminal surface, and to determine whether they might be a source of intraplaque hemorrhage (IPH). Methods We evaluated 244 surgically intact, ‘en bloc’ embedded, serially sectioned carotid endarterectomy specimens and included only those plaques with a grossly intact luminal surface. Results Among the 67 plaques with grossly intact luminal surface, cap fissure was present in 39 (58%) plaques. A total of 60 individual fissures were present, and longitudinally mean fissure length was 1.3 mm. Most fissures were found distal to the bifurcation (63%), proximal to the stenosis (88%), and in the posterior (opposite the flow divider) or lateral quadrants (80%). 36% of the fissures remained in the superficial third of the plaque. 52% extended from the lumen surface to the middle third of the plaque and 12% reached the outer third of the plaque on cross section. Fissures often occurred between two tissue planes and were connected to IPH (fresh: 63%; any type: 92%) and calcifications (43%). No correlation was found with patient characteristics such as symptom status, carotid stenosis, hypertension, diabetes, smoking and medications (statins or antiplatelet agents). Conclusions Plaque fissures are common in advanced carotid plaques with an otherwise grossly intact luminal surface and are associated with fresh intraplaque hemorrhage. As they occur on the interface between plaque components with different mechanical properties, further biomechanical studies are needed to unravel the underlying failure mechanisms. [ABSTRACT FROM AUTHOR]

Background: Intraplaque hemorrhage (IPH) is associated with atherosclerosis progression and subsequent cardiovascular events. We sought to develop a semi-automatic method with an optimized threshold for carotid IPH detection and quantification on MP-RAGE images using matched histology as the gold standard. Methods: Fourteen patients scheduled for carotid endarterectomy underwent 3D MP-RAGE cardiovascular magnetic resonance (CMR) preoperatively. Presence and area of IPH were recorded using histology. Presence and area of IPH were also recorded on CMR based on intensity thresholding using three references for intensity normalization: the sternocleidomastoid muscle (SCM), the adjacent muscle and the automatically generated local median value. The optimized intensity thresholds were obtained by maximizing the Youden's index for IPH detection. Using leave-one-out cross validation, the sensitivity and specificity for IPH detection based on our proposed semi-automatic method and the agreement with histology on IPH area quantification were evaluated. Results: The optimized intensity thresholds for IPH detection were 1.0 times the SCM intensity, 1.6 times the adjacent muscle intensity and 2.2 times the median intensity. Using the semi-automatic method with the optimized intensity threshold, the following IPH detection and quantification performance was obtained: sensitivities up to 59, 68 and 80 %; specificities up to 85, 74 and 79 %; Pearson's correlation coefficients (IPH area measurement) up to 0. 76, 0.93 and 0.90, respectively, using SCM, the adjacent muscle and the local median value for intensity normalization, after heavily calcified and small IPH were excluded. Conclusions: A semi-automatic method with good performance on IPH detection and quantification can be obtained in MP-RAGE CMR, using an optimized intensity threshold comparing to the adjacent muscle. The automatically generated reference of local median value provides comparable performance and may be particularly useful for developing automatic classifiers. Use of the SCM intensity as reference is not recommended without coil sensitivity correction when surface coils are used. [ABSTRACT FROM AUTHOR]

Correct stratification of ischemic stroke risk allows for the proper treatment of carotid atherosclerotic disease. We seek to differentiate plaque types based on stenosis level and plaque morphology. The Chinese Atherosclerosis Risk Evaluation (CARE–II) study is a cross-sectional, observational, multicenter study to assess carotid atherosclerotic plaques in symptomatic subjects using vessel wall magnetic resonance imaging. Plaque morphology and presence of plaque components were reviewed using multi-contrast magnetic resonance imaging. The carotid arteries were divided into four groups based on stenosis level and plaque components. Out of 1072 ischemic stroke subjects, 452 ipsilateral side carotid arteries were included. Significant stenosis (SS) (≥50% stenosis) with high-risk plaque (HRP) features was present in 37 arteries (8.2%), SS(+)/HRP(−) in 29 arteries (6.4%), SS(−)/HRP(+) in 57 arteries (12.6%), and SS(−)/HRP(−) in 329 arteries (72.8%). The prevalence of SS(−)/HRP(+) arteries in this cohort was substantial and had greater wall thickness than the SS(+)/HRP(−) group. These arteries may be misclassified for carotid revascularization by current guidelines based on the degree of luminal stenosis only. These findings have implications for further studies to assess stroke risk using vessel wall imaging. [ABSTRACT FROM AUTHOR]