Accurate and robust segmentation of cerebral vasculature on four-dimensional arterial spin labeling magnetic resonance angiography using machine-learning approach.

Segmentation of cerebral vasculature on MR vascular images is of great significance for clinical application and research. However, the existing cerebrovascular segmentation approaches are limited due to insufficient image contrast and complicated algorithms. This study aims to explore the potential of the emerging four-dimensional arterial spin labeling magnetic resonance angiography (4D ASL-MRA) technique for fast and accurate cerebrovascular segmentation with a simple machine-learning approach. Nine temporal features were extracted from the intensity-time signal of each voxel, and eight spatial features from the neighboring voxels. Then, the unsupervised outlier detection algorithm, i.e. Isolation Forest, is used for segmentation of the vascular voxels based on the extracted features. The total length of the centerlines of the intracranial arterial vasculature, the dice similarity coefficient (DSC), and the average Hausdorff Distance (AVGHD) on the cross-sections of small- to large-sized vessels were calculated to evaluate the performance of the segmentation approach on 4D ASL-MRA of 18 subjects. Experiments show that the temporal information on 4D ASL-MRA can largely improve the segmentation performance. In addition, the proposed segmentation approach outperforms the traditional methods that were performed on the 3D image (i.e. the temporal average intensity projection of 4D ASL-MRA) and the previously proposed frame-wise approach. In conclusion, this study demonstrates that accurate and robust segmentation of cerebral vasculature is achievable on 4D ASL-MRA by using a simple machine-learning approach with appropriate features.

Characterization of kidneys in patients with systemic sclerosis by multi-parametric magnetic resonance quantitative imaging.

PURPOSE: To determine the usefulness of multiparametric magnetic resonance (MR) quantitative imaging in characterizing the kidneys in systemic sclerosis (SSc) patients. MATERIAL AND METHODS: Forty-six SSc patients (47.9 ± 12.8 years, 40 females) and 22 age- and sex- matched healthy volunteers (46.1 ± 13.8 years, 20 females) were recruited and underwent renal MR imaging by acquiring blood oxygen level dependent and saturated multi-delay renal arterial spin labeling (SAMURAI) sequences. The T2* value, T1 value, renal blood flow (RBF), arterial bolus arrival time (aBAT), and tissue bolus arrival time (tBAT) of renal cortex were measured and compared among diffuse cutaneous SSc (dcSSc) and limited cutaneous SSc (lcSSc) groups and healthy controls using One-way ANOVA and analyzed by logistic regression. RESULTS: Compared to healthy volunteers, SSc patients with normal estimated glomerular filtration rate (n = 40) had significantly lower T2* value (P = 0.026) in the left renal cortex, longer T1 value (right: P = 0.015; left: P = 0.023), lower RBF (right: P < 0.001; left: P < 0.001), and shorter tBAT (right: P < 0.001; left: P = 0.005) in both right and left renal cortex after adjusting for demographics. The dcSSc patients (n = 23) had significantly lower RBF in both right (226.7 ± 65.2 mL/100 g/min vs. 278.2 ± 73.5 mL/100 g/min, P = 0.022) and left (194.5 ± 71.5 mL/100 g/min vs. 252.7 ± 84.4 mL/100 g/min, P = 0.020) renal cortex compared to the lcSSc patients (n = 23) after adjusting for demographics, but the significance of the difference was attenuated after further adjusting for modified Rodnan skin score and digital ulcers. CONCLUSION: Multi-parametric MR quantitative imaging, particularly multi-delay ASL perfusion imaging, is a useful technique for characterizing the kidneys and classification of SSc patients.

Atherosclerotic plaque characteristics in extracranial carotid artery may indicate closer association with white matter hyperintensities than intracranial arteries: A CARE-II study.

PURPOSE: This study aimed to investigate the associations of atherosclerotic plaque characteristics in intracranial and extracranial carotid arteries with severity of white matter hyperintensities (WMHs) in symptomatic patients using magnetic resonance (MR) imaging. METHOD: Patients with cerebrovascular symptoms and carotid plaque were recruited from the cross-sectional, multicenter study of CARE-II. Luminal stenosis of intracranial and extracranial carotid arteries, carotid plaque compositional features, and WMHs were evaluated by brain structural and vascular MR imaging. The atherosclerotic plaque characteristics in intracranial and extracranial carotid arteries were compared between patients with and without moderate-to-severe WMHs (Fazekas score > 2), and their associations with severity of WMHs were analyzed using logistic regression. RESULTS: Of the recruited 622 patients (mean age, 58.7 ± 10.9 years; 422 males), 221 (35.5 %) had moderate-to-severe WMHs with higher prevalence of moderate-to-severe luminal stenosis (17.0 % vs. 10.4 %), intraplaque hemorrhage (15.7 % vs. 9.0 %), thin/ruptured fibrous cap (30.2 % vs. 20.4 %), calcification (44.4 % vs. 22.2 %) and lipid-rich necrotic core (63.8 % vs. 51.1 %) in carotid artery compared to those without (all P < 0.05). Multivariate logistic regression showed that carotid calcification (OR, 1.854; 95 % CI, 1.187-2.898; P = 0.007) was independently associated with moderate-to-severe WMHs after adjusting for confounding factors. No significant association was found between intracranial atherosclerotic stenosis and moderate-to-severe WMHs (P > 0.05). CONCLUSION: Carotid atherosclerotic plaque features, particularly presence of calcification, were independently associated with severity of WMHs, but such association was not found in intracranial atherosclerotic stenosis, suggesting that carotid atherosclerotic plaque characteristics may have closer association with severity of WMHs compared to intracranial atherosclerosis.

Diffusing capacity of lungs for carbon monoxide associated with subclinical myocardial impairment in systemic sclerosis: A cardiac MR study.

BACKGROUND: Systemic sclerosis (SSc) is characterised by microvascular and fibrotic lesions, which are located not only in skin but also in lungs and heart. OBJECTIVE: This study aimed to investigate the association between lung function and myocardial T1 values using cardiac MR (CMR) imaging in patients with SSc without cardiovascular symptoms. METHODS: The SSc patients and age- and sex-matched healthy subjects underwent CMR. The cardiac function and native T1 values of myocardium and lung function were measured. Spearman's rank correlations and linear regression analyses were performed to determine the association between lung function and myocardial T1. RESULTS: Forty-five SSc patients (aged 47.7±13.2 years, 40 females) and 23 (aged 46.0±14.4 years, 20 females) healthy subjects were enrolled. SSc patients exhibited considerably higher native T1 values compared with healthy subjects (1305.9±49.8 ms vs 1272.6±37.6 ms, p=0.006). Linear regression analysis revealed that decrease of diffusing capacity of lungs for carbon monoxide (DLCO) in SSc patients was notably associated with myocardial native T1 value before (ß -1.017; 95% CI -1.883 to -0.151; p=0.022) and after adjusting for confounding factors (ß -1.108; 95% CI -2.053 to -0.164; p=0.023). Moderate-to-severe decrease of DLCO was found to be significantly associated with myocardial native T1 value (ß 48.006; 95% CI 17.822 to 78.190; p=0.003) after adjusting for confounding factors. CONCLUSION: DLCO inversely correlates with myocardial native T1 values in SSc patients, particularly moderate-to-severely decreased DLCO, suggesting that DLCO might be a potential indicator for subclinical myocardial impairment in SSc patients.

Carotid artery perivascular adipose tissue on magnetic resonance imaging: a potential indicator for carotid vulnerable atherosclerotic plaque.

Background: Magnetic resonance imaging (MRI) has the potential in assessing the inflammation of perivascular adipose tissue (PVAT) due to its excellent soft tissue contrast. However, evidence is lacking for the association between carotid PVAT measured by MRI and carotid vulnerable atherosclerotic plaques. This study aimed to investigate the association between signal intensity of PVAT and vulnerable plaques in carotid arteries using multi-contrast magnetic resonance (MR) vessel wall imaging. Methods: In this cross-sectional study, a total of 104 patients (mean age, 64.9±7.0 years; 86 men) with unilateral moderate-to-severe atherosclerotic stenosis referred to carotid endarterectomy (CEA) were recruited from April 2018 to December 2020 at Department of Neurosurgery of Peking University Third Hospital. All patients underwent multi-contrast MR vessel wall imaging including time-of-flight (ToF) MR angiography, black-blood T1-weighted (T1w) and T2-weighted (T2w) and simultaneous non-contrast angiography and intraplaque hemorrhage (IPH) imaging sequences. Patients with contraindications to endarterectomy or MRI examinations were excluded. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of PVAT were measured on ToF images and vulnerable plaque characteristics including IPH, large lipid-rich necrotic core (LRNC), and fibrous cap rupture (FCR) were identified. The SNR and CNR of PVAT were compared between slices with and without vulnerable plaque features using Mann-Whitney U test and their associations were analyzed using the generalized linear mixed model (GLMM). Results: Carotid artery slices with IPH (30.93±14.56 vs. 27.34±10.02; P<0.001), FCR (30.35±13.82 vs. 27.53±10.37; P=0.006), and vulnerable plaque (29.15±12.52 vs. 27.32±10.05; P=0.016) had significantly higher value of SNR of PVAT compared to those without. After adjusting for clinical confounders, the SNR of PVAT was significantly associated with presence of IPH [odds ratio (OR) =0.627, 95% confidence interval (CI): 0.465-0.847, Puncorr=0.002, PFDR=0.016] and vulnerable plaque (OR =0.762, 95% CI: 0.629-0.924, Puncorr=0.006, PFDR=0.020). However, no significant association was found between the CNR of PVAT and presence of vulnerable plaque features (all P>0.05). Conclusions: The SNR of carotid artery PVAT measured by ToF MR angiography is independently associated with vulnerable atherosclerotic plaque features, suggesting that the signal intensity of PVAT might be an effective indicator for vulnerable plaque.

Three-dimensional High-Resolution Dark-Blood Late Gadolinium Enhancement Imaging for Improved Atrial Scar Evaluation.

Background Radiofrequency ablation (RFA) is a widely used treatment for atrial fibrillation, reducing the risk of cardiac arrhythmia. Detailed visualization and quantification of atrial scarring has the potential to improve preprocedural decision-making and postprocedural prognosis. Conventional bright-blood late gadolinium enhancement (LGE) MRI can help detect atrial scars; however, its suboptimal myocardium to blood contrast inhibits accurate scar estimation. Purpose To develop and test a free-breathing LGE cardiac MRI approach that simultaneously provides high-spatial-resolution dark-blood and bright-blood images for improved atrial scar detection and quantification. Materials and Methods A free-breathing, independent navigator-gated, dark-blood phase-sensitive inversion recovery (PSIR) sequence with whole-heart coverage was developed. Two coregistered high-spatial-resolution (1.25 × 1.25 × 3 mm3) three-dimensional (3D) volumes were acquired in an interleaved manner. The first volume combined inversion recovery and T2 preparation to achieve dark-blood imaging. The second volume functioned as the reference for phase-sensitive reconstruction with built-in T2 preparation for improved bright-blood contrast. The proposed sequence was tested in prospectively enrolled participants who had undergone RFA for atrial fibrillation (mean time since RFA, 89 days ± 26 [SD]) from October 2019 to October 2021. Image contrast was compared with conventional 3D bright-blood PSIR images using the relative signal intensity difference. Furthermore, native scar area quantification obtained from both imaging approaches was compared with measurements obtained with electroanatomic mapping (EAM) as the reference standard. Results A total of 20 participants (mean age, 62 years ± 9; 16 male) who underwent RFA for atrial fibrillation were included. The proposed PSIR sequence successfully acquired 3D high-spatial-resolution volumes in all participants, with a mean scan time of 8.3 minutes ± 2.4. The developed PSIR sequence improved scar to blood contrast compared with conventional PSIR sequence (mean contrast, 0.60 arbitrary units [au] ± 0.18 vs 0.20 au ± 0.19, respectively; P < .01) and correlated with EAM regarding scar area quantification (r = 0.66 [P < .01] vs r = 0.13 [P = .63]). Conclusion In participants who had undergone RFA for atrial fibrillation, an independent navigator-gated dark-blood PSIR sequence produced high-spatial-resolution dark-blood and bright-blood images with improved image contrast and native scar quantification compared with conventional bright-blood images. © RSNA, 2023 Supplemental material is available for this article.

Single breath-hold three-dimensional whole-heart T2 mapping with low-rank plus sparse reconstruction.

The purpose of the current study was to develop and evaluate a three-dimensional single Breath-hOLd cardiac T2 mapping sequence (3D BOLT) with low-rank plus sparse (L + S) reconstruction for rapid whole-heart T2 measurement. 3D BOLT collects three highly accelerated electrocardiogram-triggered volumes with whole-heart coverage, all within a single 12-heartbeat breath-hold. Saturation pulses are performed every heartbeat to prepare longitudinal magnetization before T2 preparation (T2 -prep) or readout, and the echo time of T2 -prep is varied per volume for variable T2 weighting. Accelerated volumes are reconstructed jointly by an L + S algorithm. 3D BOLT was optimized and validated against gradient spin echo (GraSE) and a previously published approach (three-dimensional free-breathing cardiac T2 mapping [3DFBT2]) in both phantoms and human subjects (11 healthy subjects and 10 patients). The repeatability of 3D BOLT was validated on healthy subjects. Retrospective experiments indicated that 3D BOLT with 4.2-fold acceleration achieved T2 measurements comparable with those obtained with fully sampled data. T2 measured in phantoms using 3D BOLT demonstrated good accuracy and precision compared with the reference (R2 > 0.99). All in vivo imaging was successful and the average left ventricle T2 s measured by GraSE, 3DFBT2, and 3D BOLT were comparable and consistent for all healthy subjects (47.0 ± 2.3 vs. 47.7 ± 2.7 vs. 48.4 ± 1.8 ms) and patients (50.8 ± 3.0 vs. 48.6 ± 3.9 vs. 49.1 ± 3.7 ms), respectively. Myocardial T2 measured by 3D BOLT had excellent agreement with 3DFBT2 and there was no significant difference in mean, standard deviation, and coefficient of variation. 3D BOLT showed excellent repeatability (intraclass correlation coefficient: 0.938). The proposed 3D BOLT achieved whole-heart T2 mapping in a single breath-hold with good accuracy, precision, and repeatability on T2 measurements.

Reliability and Value of 3D Sequential QUantitative T1 -T2 -T2 * MAppings (SQUMA) MR Multi-Parametric Imaging in Characterizing Carotid Artery Atherosclerosis.

BACKGROUND: T1 , T2 , and T2 * mappings are seldom performed in a single examination, and their values in evaluating symptomatic atherosclerosis are lacking. PURPOSE: To perform three-dimensional (3D) quantitative T1 , T2 , and T2 * mappings (SQUMA) multi-parametric imaging for carotid vessel wall and evaluate its reliability and value in assessing carotid atherosclerosis. STUDY TYPE: Prospective. SUBJECTS: Eight healthy subjects and 20 patients with symptomatic carotid atherosclerosis. FIELD STRENGTH/SEQUENCE: 3 T, SQUMA imaging T1 -, T2 -, and T2 *-mapping, multi-contrast vessel wall imaging including T1 - and T2 -weighted, time-of-flight, and SNAP sequences. ASSESSMENT: SQUMA was acquired in all subjects and multi-contrast images were acquired in healthy subjects. T1 , T2 , and T2 * values and lumen area (LA), wall area (WA), mean wall thickness (MeanWT), and normalized wall index (NWI) of carotid arteries were measured. SQUMA and multi-contrast measurements were compared in healthy subjects and differences in SQUMA measurements between healthy subjects and patients were assessed. The discriminative value of SQUMA measurements for symptomatic vessel was determined. STATISTICAL TESTS: Paired t or Wilcoxon signed-rank test, independent t or Mann-Whitney U test, area under the receiver operating characteristic curve (AUC), intraclass correlation coefficients, and Bland-Altman plots. Statistically significant level, P < 0.05. RESULTS: There were no significant differences in LA (P = 0.340), WA (P = 0.317), MeanWT (P = 0.088), and NWI (P = 0.091) of carotid arteries between SQUMA and multi-contrast vessel wall images. The values of T2 (50.9 ± 2.9 msec vs. 44.5 ± 4.2 msec), T2 * (28.2 ± 4.3 msec vs. 24.7 ± 2.6 msec), WA (23.7 ± 4.6 mm2 vs. 36.2 ± 7.7 mm2 ), MeanWT (0.99 ± 0.05 mm vs. 1.50 ± 0.28 mm), and NWI (40.7 ± 3.0% vs. 53.8 ± 5.4%) of carotid arteries in healthy subjects were significantly different from those in atherosclerotic patients. The combination of quantitative T1 , T2 , and T2 * values and MeanWT showed greatest AUC (0.81; 95% CI: 0.65-0.92) in discriminating symptomatic vessels. DATA CONCLUSION: Carotid MR 3D quantitative multi-parametric imaging of SQUMA enables acquisition of T1 , T2 , and T2 * maps, reliably measuring carotid morphology and discriminating carotid symptomatic atherosclerosis. LEVEL OF EVIDENCE: 2 TECHNICAL EFFICACY: Stage 2.

Segmentation and differentiation of periventricular and deep white matter hyperintensities in 2D T2-FLAIR MRI based on a cascade U-net.

Background: White matter hyperintensities (WMHs) are a subtype of cerebral small vessel disease and can be divided into periventricular WMHs (pvWMHs) and deep WMHs (dWMHs). pvWMHs and dWMHs were proved to be determined by different etiologies. This study aimed to develop a 2D Cascade U-net (Cascade U) for the segmentation and differentiation of pvWMHs and dWMHs on 2D T2-FLAIR images. Methods: A total of 253 subjects were recruited in the present study. All subjects underwent 2D T2-FLAIR scan on a 3.0 Tesla MR scanner. Both contours of pvWMHs and dWMHs were manually delineated by the observers and considered as the gold standard. Fazekas scale was used to evaluate the burdens of pvWMHs and dWMHs, respectively. Cascade U consisted of a segmentation U-net and a differentiation U-net and was trained with a combined loss function. The performance of Cascade U was compared with two other U-net models (Pipeline U and Separate U). Dice similarity coefficient (DSC), Matthews correlation coefficient (MCC), precision, and recall were used to evaluate the performances of all models. The linear correlations between WMHs volume (WMHV) measured by all models and the gold standard were also conducted. Results: Compared with other models, Cascade U exhibited a better performance on WMHs segmentation and pvWMHs identification. Cascade U achieved DSC values of 0.605 ± 0.135, 0.517 ± 0.263, and 0.510 ± 0.241 and MCC values of 0.617 ± 0.122, 0.526 ± 0.263, and 0.522 ± 0.243 on the segmentation of total WMHs, pvWMHs, and dWMHs, respectively. Cascade U exhibited strong correlations with the gold standard on measuring WMHV (R2 = 0.954, p < 0.001), pvWMHV (R2 = 0.933, p < 0.001), and dWMHV (R2 = 0.918, p < 0.001). A significant correlation was found on lesion volume between Cascade U and gold standard (r > 0.510, p < 0.001). Conclusion: Cascade U showed competitive results in segmentation and differentiation of pvWMHs and dWMHs on 2D T2-FLAIR images, indicating potential feasibility in precisely evaluating the burdens of WMHs.

Slice-based and time-specific hemodynamic measurements discriminate carotid artery vulnerable atherosclerotic plaques.

BACKGROUND AND OBJECTIVE: Hemodynamic patterns play key roles in progression of carotid vulnerable plaques. However, most of previous studies utilized maximum or averaged value of hemodynamic measurements which is not an ideal representative of hemodynamic patterns. This study aimed to investigate the association of slice-based and time-specific hemodynamic measurements with carotid vulnerable plaque using magnetic resonance (MR) vessel wall imaging and histology. METHODS: Thirty-two patients (mean age: 63.9±8.1 years; 25 males) with carotid atherosclerotic stenosis (≥50% stenosis) referred to carotid endarterectomy were recruited and underwent MR vessel wall imaging. Carotid plaque burden was evaluated on MR images and vulnerable plaque features including calcification, lipid-rich necrotic core, and intra-plaque hemorrhage (IPH) were identified by histology. The slice-based and time-specific hemodynamic measurements were extracted from computational fluid dynamics simulation of 3D carotid arterial model. Correlation coefficients between hemodynamic measurements and carotid plaque features were calculated and the logistic regressions with generalized estimating equation (GEE) were conducted. The value in discriminating carotid vulnerable plaque features was determined by receiver-operating-characteristic analysis. RESULTS: Of 102 MR-histology matched slices from 32 patients, time-averaged wall shear stress (TAWSS) (r=0.263, p=0.008), oscillatory shear index (OSI) (r=-0.374, p<0.001), and peakWSS (r=0.232, p=0.019) were significantly associated with carotid IPH. The logistic regression with GEE revealed that peakWSS (OR, 1.206; 95% CI, 1.026-1.418; p, 0.023) and TAWSS (OR, 0.364, 95% CI, 0.138-0.959; p, 0.041) were significantly associated with presence of IPH after adjusting for age and BMI. In discriminating carotid IPH, the AUC of TAWSS, OSI, combined TAWSS with maximum wall thickness (MWT) and combined OSI with MWT was 0.656, 0.722, 0.761, and 0.764, respectively. CONCLUSIONS: Slice-based and time-specific hemodynamic characteristics could effectively discriminate carotid IPH. Combination of hemodynamic measurements with carotid plaque burden might be a stronger indicator for carotid vulnerable plaque features than each measurement alone.

Associations between cerebral blood flow and progression of white matter hyperintensity in community-dwelling adults: a longitudinal cohort study.

Background: White matter hyperintensity (WMH) is prevalent in elderly populations. Ischemia is characterized by a decline in cerebral blood flow (CBF) and may play a key role in the pathogenesis of WMH. However, the association between CBF reduction and WMH progression remains controversial. This study aimed to investigate the association between CBF and the progression of WMH at a 2-year follow-up of community-based, asymptomatic adults in a longitudinal cohort study across the lifespan. Methods: Asymptomatic adults who participated in a community-based study were recruited and underwent brain structural and perfusion magnetic resonance imaging (MRI) at baseline and at a 2-year follow-up visit. The CBF was measured on pseudo-continuous arterial spin-labeling (pCASL) MRI. The WMH was evaluated on T2-weighted fluid-attenuated inversion recovery (T2-FLAIR) images. Tissue segmentation was conducted on T1-weighted (T1W) images to derive binary masks of gray matter and normal-appearing white matter. Linear mixed effect models were conducted to analyze the cross-sectional and longitudinal associations between CBF and WMH. Results: A total of 229 adults (mean age 57.3±12.6 years; 94 males) were enrolled at baseline, among whom 84 participants (mean age 54.1±11.9 years; 41 males) completed a follow-up visit with a mean time interval of 2.77±0.44 years. At baseline, there was a decreasing trend in gray matter (GM) CBF with an increase of WMH burden (P=0.063), but this association was attenuated after adjusting for age (P=0.362). In the longitudinal analysis, baseline WMH volume was significantly associated with the reduction of perfusion in GM [coefficient =-1.96, 95% confidence interval (CI): -3.25 to -0.67; P=0.004] and normal appearing white matter (coefficient =-0.99, 95% CI: -1.66 to -0.31; P=0.005) during follow-up. On the contrary, neither baseline CBF in GM (P=0.888) nor normal appearing white matter (P=0.850) was associated with WMH progression. In addition, CBF changes within WMH were significantly associated with both baseline (coefficient =-0.014, 95% CI: -0.025 to -0.003; P=0.017) and progression (coefficient =-1.01, 95% CI: -1.81 to -0.20; P=0.015) of WMH volume. Conclusions: A WMH burden was not found to be directly associated with cortex perfusion at baseline due to the effects of age on both CBF and WMH. However, baseline WMH volume could predict the reduction of perfusion.

Association between antiplatelet medication and cerebral microbleeds in stroke-free population.

BACKGROUND: Cerebral microbleeds (CMBs) may increase the risk of future intracerebral hemorrhage and ischemic stroke. However, It is unclear whether antiplatelet medication is associated with CMBs. This study aimed to investigate the association between antiplatelet medication and CMBs in a community-based stroke-free population. METHODS: In this cross-sectional study, stroke-free participants aged 18-85 years were recruited from a community in Beijing, China. Demographic, clinical, and antiplatelet medication data were collected through a questionnaire, and all participants underwent blood tests and brain magnetic resonance imaging at 3.0T. The presence, count, and location of CMBs were evaluated using susceptibility-weighted imaging. The association between antiplatelet medication and the presence of CMBs was analyzed using multivariable logistic regression. The associations between antiplatelet medication and CMBs by location (lobar, deep brain or infratentorial, and mixed regions) were also analyzed using multinomial logistic regression. A linear regression analysis was conducted to determine the association between antiplatelet medication and the log-transformed number of CMBs. RESULTS: Of the 544 participants (mean age: 58.65 ± 13.66 years, 217 males), 119 participants (21.88%) had CMBs, and 64 participants (11.76%) used antiplatelet medication. Antiplatelet medication was found to be associated with CMBs at any location [odds ratio (OR) = 2.39, 95% CI: 1.24-4.58] and lobar region (OR = 2.83, 95% CI: 1.36-5.86), but not with the number of CMBs (ß = 0.14, 95% CI: -0.21-0.48). Among antiplatelet medications, aspirin use was found to be associated with any CMB (OR = 3.17, 95% CI: 1.49-6.72) and lobar CMBs (OR = 3.61, 95% CI: 1.57-8.26). CONCLUSIONS: Antiplatelet medication was associated with CMBs in stroke-free participants, particularly lobar CMBs. Among antiplatelet medications, aspirin use was associated with any CMB and lobar CMBs. Our findings suggest that it might be essential to optimize the management of antiplatelet medication in the stroke-free population with a higher burden of vascular risk factors to reduce the potential risk of CMBs.

Association between haemoglobin A1c and cerebral microbleeds in community-based stroke-free individuals: A cross-sectional study.

AIMS: The association between haemoglobin A1c (HbA1c) and cerebral microbleeds (CMBs) remains unclear. We aimed to investigate the association between HbA1c and CMBs in community-based individuals without stroke or transient ischaemic attack (TIA) and whether the association differs between individuals with and without diabetes mellitus (DM). MATERIALS AND METHODS: All individuals were recruited from a community in Beijing, China, from January 2015 to September 2019. All individuals completed a questionnaire and underwent blood tests and brain magnetic resonance imaging. A susceptibility-weighted imaging sequence was acquired to detect CMBs, which were defined as small, round and low-signal lesions with <10 mm diameter. The association between HbA1c and CMBs was analysed using multivariable logistic regression adjusted for demographics, medical history and blood sample test results. Subgroup analyses stratified by history of DM were performed. RESULTS: Of 544 recruited individuals, 119 (21.88%) had CMBs. HbA1c was independently associated with CMBs (odds ratio [OR], 1.51; 95% confidence interval [CI], 1.03-2.22). In 87 individuals with DM, multivariable logistic analysis showed that HbA1c was significantly associated with CMBs (OR, 1.67; 95% CI, 1.04-2.69), whereas in individuals without DM, no significant association was observed between HbA1c and CMBs (OR, 1.07; 95% CI, 0.50-2.30). CONCLUSIONS: HbA1c was associated with CMBs in individuals without stroke or TIA, particularly in individuals with DM, suggesting that the status of glycaemic control warrants attention for the prevention of CMBs. It would be beneficial to manage HbA1c specifically to control the risk of CMBs, especially in individuals with DM.

Saturated multi-delay renal arterial spin labeling technique for simultaneous perfusion and T1 quantification in kidneys.

PURPOSE: To propose a free-breathing simultaneous multi-delay arterial spin labeling (ASL) and T1 mapping technique with a stepwise kinetic model for renal assessment in a single 4-min scan at 3 T. METHODS: The proposed saturated multi-delay renal arterial spin labeling (SAMURAI) sequence used flow-sensitive alternating inversion recovery (FAIR) preparation, followed by acquisition of 9 images with Look-Locker spoiled gradient recalled echo (SPGR). Pre-saturation at the imaging slice was used to achieve saturation-based T1 mapping. A 4-step 2-compartment kinetic model was proposed to characterize water transition through artery- and tissue-compartment. The impact of the Look-Locker sampling scheme on the ASL signal was corrected in this model. T1 estimation with dictionary searching method and perfusion quantification based on the proposed kinetic model fitting were conducted after groupwise registration of the acquired images. The feasibility and repeatability of SAMURAI were validated in healthy subjects (n = 11) and patients with different renal diseases (n = 4). RESULTS: The proposed SAMURAI technique can provide accurate T1 map with strong correlation (R2  = 0.98) with inversion recovery spin echo (IR-SE) on phantom. SAMURAI provided equally reliable whole kidney and cortical ASL and T1 quantification results compared with multi-TI FAIR (intraclass correlation coefficient [ICC], 0.880-0.958) and IR-SPGR (ICC, 0.875-0.912), respectively. Low renal blood flow and increased T1 were detected by SAMURAI in the affected kidneys of the patients. SAMURAI had excellent scan-rescan repeatability (ICC, 0.905-0.992) and significantly reduced scan time (4 min 6 s vs. 45 min for 9 TIs) compared to multi-TI FAIR. CONCLUSION: The proposed SAMURAI technique is feasible and repeatable for simultaneously quantifying T1 and perfusion of kidneys with high time-efficiency.

Comparing Symptomatic and Asymptomatic Carotid Artery Atherosclerosis in Patients With Bilateral Carotid Vulnerable Plaques Using Magnetic Resonance Imaging.

We compared plaque characteristics between symptomatic and asymptomatic sides in patients with bilateral carotid vulnerable plaques using magnetic resonance imaging (MRI). Participants (n = 67; mean age: 65.8 ± 7.7 years, 61 males) with bilateral carotid vulnerable plaques were included. Vulnerable plaques were characterized by intraplaque hemorrhage (IPH), large lipid-rich necrotic core (LRNC), or fibrous cap rupture (FCR) on MRI. Symptomatic vulnerable plaques showed greater plaque burden, LRNC volume (median: 221.4 vs 134.8 mm3, P = .003), IPH volume (median: 32.2 vs 22.5 mm3, P = .030), maximum percentage (Max%) LRNC (median: 51.3% vs 41.8%, P = .002), Max%IPH (median: 13.4% vs 9.5%, P = .022), cumulative slices of LRNC (median: 10 vs 8, P = .005), and more juxtaluminal IPH and/or thrombus (29.9% vs 6.0%, P = .001) and FCR (37.3% vs 16.4%, P = .007) than asymptomatic ones. After adjusting for plaque burden, differences in juxtaluminal IPH and/or thrombus (odds ratio [OR]: 5.49, 95% CI: 1.61-18.75, P = .007) and FCR (OR: 2.90, 95% CI: 1.16-7.24, P = .022) between bilateral sides remained statistically significant. For patients with bilateral carotid vulnerable plaques, symptomatic plaques had greater burden, more juxtaluminal IPH and/or thrombus, and FCR compared with asymptomatic ones. The differences in juxtaluminal IPH and/or thrombus and FCR between bilateral sides were independent of plaque burden.

Free-breathing three-dimensional isotropic-resolution MR sequence for simultaneous vessel wall imaging of bilateral renal arteries and abdominal aorta: Feasibility and reproducibility.

PURPOSE: Many diseases can simultaneously involve renal arteries and the adjacent abdominal aorta. This study proposed a free-breathing three-dimensional (3D) isotropic-resolution magnetic resonance sequence for simultaneous vessel wall imaging (VWI) of bilateral renal arteries and adjacent abdominal aorta. METHODS: A respiratory-triggered isotropic-resolution sequence that combined the improved motion-sensitized driven-equilibrium (iMSDE) preparation with the spoiled gradient recalled (SPGR) readout (iMSDE-SPGR) was proposed for simultaneous VWI of renal arteries and abdominal aorta. The proposed iMSDE-SPGR sequence was optimized by positioning spatial saturation pulses (i.e., REST slabs) elaborately to further alleviate respiratory and gastrointestinal motion artifacts and selecting appropriate first-order gradient moment (m1 ) of the iMSDE preparation. Thirteen healthy subjects and 13 patients with renal artery stenosis underwent simultaneous VWI with the optimized iMSDE-SPGR sequence at 3.0 T. Signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and morphology of renal arterial wall and aortic wall were measured. Reproducibility of intra-observer, inter-observer, and scan-rescan (n = 13 healthy subjects) in measuring SNR, CNR, and morphology was evaluated. For the reproducibility test, the agreement was determined using intraclass correlation coefficients (ICC), and the differences were compared using paired t-test or nonparametric Wilcoxon test when appropriate. Bland-Altman plots were used to calculate the bias between observers and between scans. RESULTS: The proposed iMSDE-SPGR sequence was feasible for simultaneous VWI both in the healthy subjects and the patients. The sequence showed good to excellent inter-observer (ICC: 0.615-0.999), excellent intra-observer (ICC: 0.801-0.998), and scan-rescan (ICC: 0.768-0.998) reproducibility in measuring morphology, SNR, and CNR. There were no significant differences in SNR, CNR, and morphology measurements between observers and between scans (all p > 0.05). Bland-Altman plots showed small bias in assessing SNR, CNR, and morphology. DATA CONCLUSION: The proposed free-breathing 3D isotropic-resolution iMSDE-SPGR technique is feasible and reproducible for simultaneous VWI of bilateral renal arteries and adjacent abdominal aorta.

Evaluating renal arterial wall by non-enhanced 2D and 3D free-breathing black-blood techniques: Initial experience.

OBJECTIVES: To evaluate the feasibility and reproducibility of 2D and 3D black-blood sequences in measuring morphology of renal arterial wall. METHODS: The 2D and 3D imaging sequences used variable-refocusing-flip-angle and constant-low-refocusing-flip-angle turbo spin echo (TSE) readout respectively, with delicately selected black-blood scheme and respiratory motion trigger for free-breathing imaging. Fourteen healthy subjects and three patients with Takayasu arteritis underwent renal artery wall imaging with 3D double inversion recovery (DIR) TSE and 2D Variable Flip Angle-TSE (VFA-TSE) black-blood sequences at 3.0 T. Four healthy subjects were randomly selected for scan-rescan reproducibility experiments. Signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR) and morphology of arterial wall were measured and compared using paired-t-test or Wilcoxon signed-rank test between 2D and 3D sequences. The inter-observer, intra-observer and scan-rescan agreements of above measurements were determined using intraclass correlation coefficient (ICC). RESULTS: The 2D and 3D imaging sequences showed similar morphological measurements (lumen area, wall area, mean wall thickness and maximum wall thickness) of renal arterial wall (all P > 0.05) and excellent agreement (ICC: 0.853-0.954). Compared to 2D imaging, 3D imaging exhibited significantly lower SNRlumen (P < 0.01) and SNRwall (P = 0.037), similar contrast-to-noise ratio (CNR) (P = 0.285), and higher CNR efficiency (CNReff) (P < 0.01). Both 2D and 3D imaging showed good to excellent inter-observer (ICC: 0.723-0.997), intra-observer (ICC: 0.749-0.996) and scan-rescan (ICC: 0.710-0.992) reproducibility in measuring renal arterial wall morphology, SNR and CNR, respectively. CONCLUSIONS: Both high-resolution free-breathing 2D VFA-TSE and 3D DIR TSE black-blood sequences are feasible and reproducible in high-resolution renal arterial wall imaging. The 2D imaging has high SNR, whereas 3D imaging has high imaging efficiency.