Background and purposeAtherosclerosis is a very complex process influenced by various systemic and local factors. Therefore, in patients with bilateral carotid plaques (BCPs), there may be differences in carotid plaque vulnerability between the sides. We aimed to investigate the differences in BCP characteristics in patients with BCPs using magnetic resonance vessel wall imaging (MR-VWI). MethodsParticipants with BCPs were selected for subanalysis from a multicentre study of Chinese Atherosclerosis Risk Evaluation II. We measured carotid plaque burden, identified each plaque component and measured their volume or area bilaterally on MR-VWI. Paired comparisons of the burden and components of BCPs were performed. ResultsIn all, 540 patients with BCPs were eligible for analysis. Compared with the right carotid artery (CA), larger mean lumen area (p<0.001), larger mean wall area (p=0.025), larger mean total vessel area (p<0.001) and smaller normalised wall index (p=0.006) were found in the left CA. Regarding plaque components, only the prevalence of lipid-rich necrotic core (LRNC) in the left CA was higher (p=0.026). For patients with a vulnerable plaque component coexisting on both sides, only the intraplaque haemorrhage (IPH) volume (p=0.011) was significantly greater in the left CA than in the right CA. ConclusionsThere were asymmetries in plaque growth and evolution between BCPs. The left carotid plaques were more likely to have larger plaque burden, higher prevalence of LRNC and greater IPH volume, which may contribute to the lateralisation of ischaemic stroke in the cerebral hemispheres.

Atherosclerotic plaques prone to rupture may cause acute myocardial infarction (MI) but can also heal without causing an event. Certain common histopathological features, including inflammation, a thin fibrous cap, positive remodelling, a large necrotic core, microcalcification, and plaque haemorrhage are commonly found in plaques causing an acute event. Recent advances in imaging techniques have made it possible to detect not only luminal stenosis and overall coronary atherosclerosis burden but also to identify such adverse plaque characteristics. However, the predictive value of identifying individual adverse atherosclerotic plaques for future events has remained poor. In this Position Paper, the relationship between vulnerable plaque imaging and MI is addressed, mainly for non-invasive assessments but also for invasive imaging of adverse plaques in patients undergoing invasive coronary angiography. Dynamic changes in atherosclerotic plaque development and composition may indicate that an adverse plaque phenotype should be considered at the patient level rather than for individual plaques. Imaging of adverse plaque burden throughout the coronary vascular tree, in combination with biomarkers and biomechanical parameters, therefore holds promise for identifying subjects at increased risk of MI and for guiding medical and invasive treatment.

目的:颈动脉粥样硬化斑块的形成是脑血管病变的独立危险因素之一.对颈动脉内膜剥脱术(carotid endarterectomy,CEA)斑块进行充分的组织学判读和研究,将有助于全面把握CEA斑块的组织学表现,进而推进临床辅助诊断.方法:本文我们将运用数字病理扫描仪对CEA斑块的切片经H&E染色后进行扫描,介绍数字病理扫描在CEA斑块组织学研究中的应用.结果 经数字病理扫描所得的图片,有助于全面掌握和保存CEA斑块组织切片的全层面信息;在软件的帮助下有助于非常方便地测量斑块内各成分的大小;有助于精确评估斑块的狭窄程度.结论:综上,数字病理成像应用于CEA斑块,结合MRI,有助于高效且准确地判读斑块组成和预测斑块稳定性,亦有助于人工智能的训练.

背景:在颈动脉粥样硬化斑块的石蜡包埋工作中,将平均长度约3 cm的颈动脉粥样硬化斑块组织完整地包埋入蜡块中是上述科研工作必须步骤。目的:阐述一种颈动脉粥样硬化斑块整块石蜡包埋处理方法。方法:颈动脉粥样硬化斑块组织取自首都医科大学附属北京天坛医院经颈动脉内膜剥脱术手术取材样本。为了便于连续切片后的组织学层面能够与磁共振成像的信息作精准同层比对,实验在组织石蜡包埋时将颈动脉粥样硬化斑块组织作为一个整体完整地包埋入蜡块中。结果与结论:在实际工作中,借鉴合作方美国华盛顿大学血管成像实验室在斑块处理方面的实践经验,结合实验室的实际情况,通过一种简易包埋方法进行颈动脉粥样硬化斑块的整块石蜡包埋,克服了颈动脉粥样硬化斑块组织整块包埋中的技术难点,为有类似工作需求的同行提供参考和引用。

Purpose To propose a technique that can produce different T 1 and T 2 contrasts in a single scan for simultaneous T 1 and T 2 mapping of the carotid plaque (SIMPLE). Methods An interleaved 3D golden angle radial trajectory was used in conjunction with T 2 preparation with variable duration (TE prep ) and inversion recovery pulses. Sliding window reconstruction was adopted to reconstruct images at different inversion delay time and TE prep for joint T 1 and T 2 fitting. In the fitting procedure, a rapid B 1 correction method was presented. The accuracy of SIMPLE was investigated in phantom experiments. In vivo scans were performed on 5 healthy volunteers with 2 scans each, and on 5 patients with carotid atherosclerosis. Results The phantom T 1 and T 2 estimations of SIMPLE agreed well with the standard methods with the percentage difference smaller than 7.1%. In vivo T 1 and T 2 for normal carotid vessel wall were 1213 ± 48.3 ms and 51.1 ± 1.7 ms, with good interscan repeatability. Alternations of T 1 and T 2 in plaque regions were in agreement with the conventional multicontrast imaging findings. Conclusion The proposed SIMPLE allows simultaneous T 1 and T 2 mapping of the carotid artery in less than 10 minutes, serving as a quantitative tool with good accuracy and reproducibility for plaque characterization.

>100多年来,医学影像技术迅速发展,已经成为医疗诊断中不可或缺的技术。进入数字影像时代以来,海量数据的产生为医学影像未来的发展提供了更多的可能性。因此,如何对医学影像大数据做进一步分析和挖掘、如何从医学图像高维度数据中提取有价值的信息、如何将现代医学影像的发展与精准医疗紧密结合,成为医学影像未来发展的重要课题。近年来,随着计算能力的增强和数据的爆

PURPOSE:Multishot interleaved echo-planar imaging (iEPI) can achieve higher image resolution than single-shot EPI for diffusion tensor imaging (DTI), but its application is limited by the prolonged acquisition time. To reduce the acquisition time, a novel model-based reconstruction for simultaneous multislice (SMS) and parallel imaging (PI) accelerated iEPI DTI is proposed. MATERIALS AND METHODS:DTI datasets acquired by iEPI with SMS and PI acceleration can be regarded as 3D k-space data, which is undersampled along both the slice and phase encoding directions. Instead of reconstruction of individual diffusion-weighted image, diffusion tensors are directly estimated by the joint reconstruction of undersampled 3D k-space from all diffusion-encoding directions using a model-based formulation to exploit the correlation across different directions. DTI simulation and in vivo acquisition were used to demonstrate the superior performance of the proposed method. RESULTS:The proposed method reduced the estimation errors and artifacts than traditional parallel imaging reconstruction in DTI simulation. In the in vivo DTI experiment, the acquisition time of 4-shot iEPI was reduced from 11 min 7 s to 3 min 53 s with an acceleration factor of 4, and the image quality and precision of quantitative parameters were comparable with the fully sampled acquisition. CONCLUSIONS:The proposed model-based reconstruction for iEPI DTI with SMS and PI can achieve fourfold acceleration while maintaining high accuracy for tensor measurements.

OBJECTIVE:This study sought to investigate the relationship of atherosclerosis between intracranial and extracranial carotid arteries using three-dimensional multicontrast magnetic resonance (MR) vessel wall imaging.METHODS:Patients with recent cerebrovascular symptoms in anterior circulation were recruited and underwent MR vessel wall imaging for intracranial and extracranial carotid arteries. The plaque burden, including maximum wall thickness (Max WT) and stenosis, and presence of intraplaque hemorrhage (IPH) were assessed. The correlation of the plaque characteristics between intracranial and extracranial carotid arteries was determined.RESULTS:In total, 107 patients (mean age: 57.0 ± 11.1 years, 69 males) were recruited. In discriminating intracranial severe stenosis (≥50% stenosis), the odds ratio (OR) of Max WT of extracranial carotid arteries was 1.41 (95% confidence interval [CI], 0.94-2.11, P = 0.095) and 1.72 (95% CI, 1.04-2.83, P = 0.034) before and after adjusting for confounding factors, respectively. The OR of stenosis of extracranial carotid arteries with increment of 10% was 1.26 (95% CI, 0.99-1.60, P = 0.054) and 1.37 (95% CI, 1.03-1.82, P = 0.033) before and after adjusting for confounding factors, in discriminating intracranial severe stenosis respectively. Receiver operating characteristic analysis revealed that the area under the curve (AUC) of Max WT, stenosis, and IPH of extracranial carotid artery plaques was 0.641, 0.605, and 0.603 in discriminating intracranial severe stenosis, respectively. After adjusting for confounding factors, the AUC of Max WT, stenosis, and presence of IPH in extracranial carotid artery plaques increased to 0.812, 0.817 and 0.781, respectively.INTERPRETATION:Carotid artery plaque burden is significantly associated with severe intracranial artery stenosis, suggesting that extracranial carotid plaque burden might be an independent indicator for severity of intracranial artery atherosclerosis.

Objective To evaluate the influences of statin treatment on MR vessel wall imagingobserved characteristics of atherosclerotic plaque in the thoracic aorta of the elderly.Methods Elderly subjects (≥ 60 years) without any serious cerebro-cardiovascular diseases were recruited.Thoracic aorta was imaged on MR scanner for all the subjects.The plaque burden was calculated quantitatively,the composition of plaque in thoracic aorta was evaluated qualitatively,and the contributions of statin treatment to these characteristics were also compared by image interpretation personals.The thoracic aorta was divided into three segments (AAO:ascending aorta;AOA:aortic arch,and DOA:descending aorta)on the imaging.Results Totally 55 recruited subjects had atherosclerotic plaque in thoracic aorta,with 24 subjects receiving statin treatment,and 50 ％ (12/24) male,aged 73.8±6.3 years.The level of LDL C[(2.4±0.7)mmol/L vs.(3.1±0.8)mmol/L(P＜ 0.01)]and total cholesterol[(4.4±0.6)mmol/L vs.(5.1 ±1.0)mmol/L(P＜0.01)]were significantly lower in statin group than in non-statin group.The lumen area,wall area,and total vessel area in all three segments of thoracic aorta were significantly smaller in statin group(all P＜0.05)than in nonstatin group.The average wall thickness in segment of AOA[(2.7±0.3)mm vs.(2.8±0.4)mm(P＜0.01)]and DAO[(2.5±0.4)mm vs.(2.6±0.5)mm(P＜0.01)]were smaller in statin group than in non-statin group.The incidence rate of intraplaque hemorrhage / mural thrombus [6 cases (25.0％) vs.8 cases(25.8 ％)]in thoracic aorta was a little lower in statin group than in non-statin group,with no significant difference(P＞0.05).Conclusions Statin treatment decreases LDL-C level,reduces the burden of atherosclerotic plaque in thoracic aorta,and maintains the atherosclerotic plaque stability.

PurposeTo propose a simultaneous acquisition sequence for improved hepatic pharmacokinetics quantification accuracy (SAHA) method for liver dynamic contrast‐enhanced MRI.MethodsThe proposed SAHA simultaneously acquired high temporal‐resolution 2D images for vascular input function extraction using Cartesian sampling and 3D large‐coverage high spatial‐resolution liver dynamic contrast‐enhanced images using golden angle stack‐of‐stars acquisition in an interleaved way. Simulations were conducted to investigate the accuracy of SAHA in pharmacokinetic analysis. A healthy volunteer and three patients with cirrhosis or hepatocellular carcinoma were included in the study to investigate the feasibility of SAHA in vivo.ResultsSimulation studies showed that SAHA can provide closer results to the true values and lower root mean square error of estimated pharmacokinetic parameters in all of the tested scenarios. The in vivo scans of subjects provided fair image quality of both 2D images for arterial input function and portal venous input function and 3D whole liver images. The in vivo fitting results showed that the perfusion parameters of healthy liver were significantly different from those of cirrhotic liver and HCC.ConclusionsThe proposed SAHA can provide improved accuracy in pharmacokinetic modeling and is feasible in human liver dynamic contrast‐enhanced MRI, suggesting that SAHA is a potential tool for liver dynamic contrast‐enhanced MRI. Magn Reson Med 79:2629–2641, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

PURPOSE:To develop a novel diffusion imaging reconstruction framework based on iterative self-consistent parallel imaging reconstruction (SPIRiT) for multishot interleaved echo planar imaging (iEPI), with computation acceleration by virtual coil compression. METHODS:As a general approach for autocalibrating parallel imaging, SPIRiT improves the performance of traditional generalized autocalibrating partially parallel acquisitions (GRAPPA) methods in that the formulation with self-consistency is better conditioned, suggesting SPIRiT to be a better candidate in k-space-based reconstruction. In this study, a general SPIRiT framework is adopted to incorporate both coil sensitivity and phase variation information as virtual coils and then is applied to 2D navigated iEPI diffusion imaging. To reduce the reconstruction time when using a large number of coils and shots, a novel shot-coil compression method is proposed for computation acceleration in Cartesian sampling. Simulations and in vivo experiments were conducted to evaluate the performance of the proposed method. RESULTS:Compared with the conventional coil compression, the shot-coil compression achieved higher compression rates with reduced errors. The simulation and in vivo experiments demonstrate that the SPIRiT-based reconstruction outperformed the existing method, realigned GRAPPA, and provided superior images with reduced artifacts. CONCLUSION:The SPIRiT-based reconstruction with virtual coil compression is a reliable method for high-resolution iEPI diffusion imaging. Magn Reson Med 79:1525-1531, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

Diffusion imaging is a promising technique as it can provide microstructural tissue information and thus potentially show viable changes in spinal cord. However, the traditional single‐shot imaging method is limited as a result of various image artifacts. In order to improve measurement accuracy, we used a newly developed, multi‐shot, high‐resolution, diffusion tensor imaging (DTI) method to investigate diffusion metric changes and compare them with T2‐weighted (T2W) images before and after decompressive surgery for cervical spondylotic myelopathy (CSM). T2W imaging, single‐shot DTI and multi‐shot DTI were employed to scan seven patients with CSM before and 3 months after decompressive surgery. High signal intensities were scored using the T2 W images. DTI metrics, including fractional anisotropy (FA), axial diffusivity (AD), radial diffusivity (RD) and mean diffusivity (MD), were quantified and compared pre‐ and post‐surgery. In addition, the relationship between imaging metrics and neurological assessments was examined. The reproducibility of multi‐shot DTI was also assessed in 10 healthy volunteers. Post‐surgery, the mean grade of cervical canal stenosis was reduced from grade 3 to normal after 3 months. Compared with single‐shot DTI, multi‐shot DTI provided better images with lower artifact levels, especially following surgery, as a result of reduced artifacts from metal implants. The new method also showed acceptable reproducibility. Both FA and RD values from the new acquisition showed significant differences post‐surgery (FA, p = 0.026; RD, p = 0.048). These changes were consistent with neurological assessments. In contrast, T2W images did not show significant changes before and after surgery. Multi‐shot diffusion imaging showed improved image quality over single‐shot DWI, and presented superior performance in diagnosis and recovery monitoring for patients with CSM compared with T2W imaging. DTI metrics can reflect the pathological conditions of spondylotic spinal cord quantitatively and may serve as a sensitive biomarker for potential CSM management.

Purpose The thoracic aortic atherosclerotic plaque is an important source of ischemic stroke embolism in the elderly.This study aims to explore the characteristics of vulnerable plaque of atherosclerosis in the thoracic aorta in the elderly by using three-dimensional multi-contrast magnetic resonancewall imaging technique,so as to actively prevent the occurrence of cardiovascular and cerebrovascular complications.Materials and Methods Fifty-three cases of elderly subjects (＞60 years old) without serious cerebrovascular diseases were recruited in this prospective study.All subjects were divided into A and B groups (60-74 and 75-90 years old).All subjects underwent MRI of multiple contrast sequences of the aortic wall.The thoracic aorta was divided into three segments of ascending aorta,aortic arch and descending aorta,and the characteristics of the atherosclerotic plaque were evaluated.The load characteristics of thoracic aortic atherosclerotic plaques in the elderly were calculated quantitatively,and the compositional characteristics were evaluated qualitatively.Results The incidence of intraplaque hemorrhage in the thoracic aortic atherosclerotic plaque in the elderly was 26.4％ (14/53),and the incidence of lipid nucleus was 94.3％ (50/53).Meanwhile,the maximum wall thickness of three segments of ascending aorta,aortic arch and descending aorta in group B was significantly higher than that in group A [(3.1±0.6) mm vs (3.0±0.4) mm,P＜0.05;(3.2±0.7) mm vs (3.1 ±0.7) mm,P＜0.05;(3.0±0.8) mm vs (2.9±0.7) mm,P＜0.001];the normalized wall index of the three segments in group B was significantly higher than that in group A [(26.9±3.5)％ vs (26.7±2.9)％,P＜0.001;(31.9±5.1)％ vs (31.0±5.1)％,P＜0.001;(34.6±5.0)％ vs (34.1 ±4.6)％,P＜0.001)].Conclusion The incidence of hemorrhage in the atherosclerotic plaque in the thoracic aorta in the elderly is higher,and the plaque load increases with age.Therefore,early screening of vulnerable plaque in the thoracic aorta in the elderly using magnetic resonance wall imaging will be helpful for prevention and treatment of stroke.

PURPOSE:To propose a large coverage black-bright blood interleaved imaging sequence (LaBBI) for 3D dynamic contrast-enhanced MRI (DCE-MRI) of the vessel wall. METHODS:LaBBI consists of a 3D black-blood stack-of-stars golden angle radial acquisition with high spatial resolution for vessel wall imaging and a 2D bright-blood Cartesian acquisition with high temporal resolution for arterial input function estimation. The two acquisitions were performed in an interleaved fashion within a single scan. Simulations, phantom experiments, and in vivo tests in three patients were performed to investigate the feasibility and performance of the proposed LaBBI. RESULTS:In simulation tests, the estimated Ktrans and vp by LaBBI were more accurate than conventional bright-blood DCE-MRI with lower root mean square error in all the tested conditions. In phantom test, no signal interference was found on the 2D scan in LaBBI. Pharmacokinetic analysis of the patients' data acquired by LaBBI showed that Ktrans was higher in fibrous tissue (0.0717 ± 0.0279 min-1 ), while lower in necrotic core (0.0206 ± 0.0040 min-1 ) and intraplaque hemorrhage (0.0078 ± 0.0007 min-1 ), compared with normal vessel wall (0.0273 ± 0.0052 min-1 ). CONCLUSION:The proposed LaBBI sequence, with high spatial and temporal resolution, and large coverage blood suppression, was promising to probe the perfusion properties of vessel wall lesions. Magn Reson Med 79:1334-1344, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

PURPOSE:To determine whether pharmacokinetic modeling parameters with different output assumptions of dynamic contrast-enhanced MRI (DCE-MRI) using Gd-EOB-DTPA correlate with serum-based liver function tests, and compare the goodness of fit of the different output assumptions. METHODS:A 6-min DCE-MRI protocol was performed in 38 patients. Four dual-input two-compartment models with different output assumptions and a published one-compartment model were used to calculate hepatic function parameters. The Akaike information criterion fitting error was used to evaluate the goodness of fit. Imaging-based hepatic function parameters were compared with blood chemistry using correlation with multiple comparison correction. RESULTS:The dual-input two-compartment model assuming venous flow equals arterial flow plus portal venous flow and no bile duct output better described the liver tissue enhancement with low fitting error and high correlation with blood chemistry. The relative uptake rate Kir derived from this model was found to be significantly correlated with direct bilirubin (r = -0.52, P = 0.015), prealbumin concentration (r = 0.58, P = 0.015), and prothrombin time (r = -0.51, P = 0.026). CONCLUSION:It is feasible to evaluate hepatic function by proper output assumptions. The relative uptake rate has the potential to serve as a biomarker of function. Magn Reson Med 78:1488-1495, 2017. © 2016 International Society for Magnetic Resonance in Medicine.

Objective To investigate the characteristics of atherosclerotic plaque components and burden in the thoracic aorta in the elderly with and without hyperlipidemia,by magnetic resonance vessel wall imaging.Methods Elderly subjects (≥60 years) without serious cerebrovascular diseases were recruited in this study.Thoracic aorta was imaged on MR scanner by acquiring multicontrast vessel wall imaging sequences.The plaque burden was calculated quantitatively,the composition of plaque in the thoracic aorta was evaluated qualitatively,and the correlation was investigated with hyperlipidemia.The characteristics of atherosclerosis among different thoracic aorta segments (AAO:ascending aorta;AOA:aortic arch,and DOA:descending aorta) were determined.Results Of 66 recruited subjects,43 were in hyperlipidemia group,the mean age was 72.7 ±6.8 years old,and 16 (44.2％) were male.The prevalence of plaque (95.3％ vs 60.9％,P =0.001) in thoracic aorta was significantly higher in hyperlipidemia group than in normal blood lipid group.Meanwhile,the incidence of lipid rich necrotic core was significantly greater (88.4％ vs 52.2％,P =0.001) in hyperlipidemia group,but no significant difference was found in intraplaque hemorrhage/mural thrombus (20.9％ vs 21.7％,P =0.939) between the two groups.The lumen area in all three segments was significantly smaller,and wall area and maximum wall thickness were larger in hyperlipidemia group than in another group (P ＜ 0.05).Besides,there was significant correlation between thoracic aortic plaque (OR =-0.311,P =0.011),lipid rich necrotic core (OR =-0.591,P ＜ 0.001) and high-density lipoprotein.Significant correlation was found between intraplaque hemorrhage/mural thrombus and triglyceride (OR =0.25,P=0.043).Conclusion The incidence of plaque in the thoracic aorta was significantly higher in the elderly with hyperlipidemia,the lipid rich necrotic core was dominant composition,and was closely related with the decrease of high-density lipoprotein.

Atherosclerosis is among the leading causes of death and disability. Combining information from multi-modal vascular images is an effective and efficient way to diagnose and monitor atherosclerosis, in which image registration is a key technique. In this paper a feature-based registration algorithm, Two-step Auto-labeling Conditional Iterative Closed Points (TACICP) algorithm, is proposed to align three-dimensional carotid image datasets from ultrasound (US) and magnetic resonance (MR). Based on 2D segmented contours, a coarse-to-fine strategy is employed with two steps: rigid initialization step and non-rigid refinement step. Conditional Iterative Closest Points (CICP) algorithm is given in rigid initialization step to obtain the robust rigid transformation and label configurations. Then the labels and CICP algorithm with non-rigid thin-plate-spline (TPS) transformation model is introduced to solve non-rigid carotid deformation between different body positions. The results demonstrate that proposed TACICP algorithm has achieved an average registration error of less than 0.2mm with no failure case, which is superior to the state-of-the-art feature-based methods.

Occlusion of lenticulostriate arteries (LSAs) often leads to lacunar infarction. Digital subtraction angiography (DSA) has high spatial resolution and superior definition of small vessels, and is the most widely used clinical routine to image LSAs. One drawback of DSA, however, is its invasiveness. Time-of-flight (TOF) magnetic resonance angiography (MRA) was recently shown to be able to image LSAs at ultra-high fields (i.e., 7 T) with specially-designed receiving coils. However, image LSAs with TOF-MRA on clinical MRI systems can be difficult due to the facts that blood flow in LSAs is slow and the luminal diameters in these vessels are small (i.e., 0.3~0.7 mm) relative to the dimension of imaging voxels. In this study, the flow-sensitive black-blood (FSBB) technique was optimized to image LSAs at 3 T to achieve a proper balance among spatial resolution, signal-to-noise ratio and scan time.