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1.
Arterioscler Thromb Vasc Biol ; 40(5): 1383-1391, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32160772

RESUMO

OBJECTIVE: Carotid bifurcation geometry has been believed to be a risk factor for the initiation of atherosclerosis because of its influence on hemodynamics. However, the relationships between carotid bifurcation geometry and plaque vulnerability are not fully understood. This study aimed to determine the association between carotid bifurcation geometry and plaque vulnerability using magnetic resonance vessel wall imaging. Approach and Results: A total of 501 carotid arteries with nonstenotic atherosclerosis were included from the cross-sectional, multicenter CARE II study (Chinese Atherosclerosis Risk Evaluation). Four standardized carotid bifurcation geometric parameters (bifurcation angle, internal carotid artery planarity, luminal expansion FlareA, and tortuosity Tort2D) were derived from time-of-flight magnetic resonance angiography. Presence of vulnerable plaque, which was characterized by intraplaque hemorrhage, large lipid-rich necrotic core, or disrupted luminal surface, was determined based on multicontrast carotid magnetic resonance vessel wall images. Vulnerable plaques (N=43) were found to occur at more distal locations (ie, near the level of flow divider) than stable plaques (N=458). Multivariable logistic regression showed that the luminal expansion FlareA (odds ratio, 0.45 [95% CI, 0.25-0.81]; P=0.008) was associated with plaque vulnerability after adjustment for age, sex, maximum wall thickness, plaque location, and other geometric parameters. CONCLUSIONS: Smaller luminal expansion at carotid bifurcation is associated with vulnerable plaque. The finding needs to be verified with longitudinal studies and the underlying mechanism should be further explored with hemodynamics measurement in the future.

2.
Magn Reson Med ; 84(2): 1024-1034, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32017236

RESUMO

PURPOSE: To develop a reproducible and fast method to reconstruct MR fingerprinting arterial spin labeling (MRF-ASL) perfusion maps using deep learning. METHOD: A fully connected neural network, denoted as DeepMARS, was trained using simulation data and added Gaussian noise. Two MRF-ASL models were used to generate the simulation data, specifically a single-compartment model with 4 unknowns parameters and a two-compartment model with 7 unknown parameters. The DeepMARS method was evaluated using MRF-ASL data from healthy subjects (N = 7) and patients with Moymoya disease (N = 3). Computation time, coefficient of determination (R2 ), and intraclass correlation coefficient (ICC) were compared between DeepMARS and conventional dictionary matching (DM). The relationship between DeepMARS and Look-Locker PASL was evaluated by a linear mixed model. RESULTS: Computation time per voxel was <0.5 ms for DeepMARS and >4 seconds for DM in the single-compartment model. Compared with DM, the DeepMARS showed higher R2 and significantly improved ICC for single-compartment derived bolus arrival time (BAT) and two-compartment derived cerebral blood flow (CBF) and higher or similar R2 /ICC for other parameters. In addition, the DeepMARS was significantly correlated with Look-Locker PASL for BAT (single-compartment) and CBF (two-compartment). Moreover, for Moyamoya patients, the location of diminished CBF and prolonged BAT shown in DeepMARS was consistent with the position of occluded arteries shown in time-of-flight MR angiography. CONCLUSION: Reconstruction of MRF-ASL with DeepMARS is faster and more reproducible than DM.

3.
Magn Reson Imaging ; 66: 199-207, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31493474

RESUMO

PURPOSE: To theoretically compare the MR angiography (MRA) contrast mechanism of Time of Flight (TOF) and Simultaneous Non-contrast Angiography and intraPlaque hemorrhage (SNAP) for intracranial artery imaging with in-vivo validation. METHODS: The contrast ratio (CR) of SNAP and TOF was simulated under different blood velocities and travel distance that the blood had flown through. The CR and the slope of CR with respect to blood velocity of SNAP and TOF were compared in theoretical simulation. Two healthy subjects (a 60 years old female and a 29 years old male) were imaged on a 3 T MR scanner with SNAP, TOF and phase contrast (PC) images as the validation set. The measured CR from the images in validation set was compared with the theoretically simulated CR by Person's correlation coefficient. The ratio of CR difference to velocity difference in the validation set was compared between TOF and SNAP with Student's t-test. Thirty patients (21 males, age: 48 ±â€¯13.8 years) with carotid artery atherosclerotic plaque were imaged with both TOF and SNAP as the comparison test. Between TOF and SNAP, the CR and total artery length were compared with Student's t-test, and the prevalence of stenosis was compared with Cohen's kappa in comparison test. RESULTS: The theoretically simulated CR was significantly correlated with in-vivo measured CR from the validation set for TOF (p < 0.001) and SNAP (p < 0.001). The simulation revealed that the CR of SNAP was higher than that of TOF when the blood velocity and travel distance were within the range to have effective MRA contrast. Similarly, the in-vivo comparison test showed that SNAP had higher CR (p < 0.001 for all tested intracranial arteries) and longer total artery length (1.4 ±â€¯0.4 m vs 1.2 ±â€¯0.2 m, p < 0.001) than TOF. The stenosis detection performance was similar between TOF and SNAP (Cohen's kappa 0.72; 95% confidence interval: 0.51-0.93). Moreover, compared with TOF, SNAP showed higher slope of CR with respect to velocity in simulation (0.06 ±â€¯0.02 s/cm vs 0.02 ±â€¯0.05 s/cm, p < 0.001), and higher ratio of CR difference to velocity difference in validation test (0.47 ±â€¯0.38 s/cm vs 0.19 ±â€¯0.38 s/cm, p = 0.001). CONCLUSIONS: Compared with TOF, the SNAP shows better performance to visualize distal intracranial artery and worse performance to visualize ICA, and is more sensitive to blood velocity.

4.
Magn Reson Imaging ; 60: 93-100, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-30959178

RESUMO

PURPOSE: This study sought to determine the feasibility of using Simultaneous Non-contrast Angiography and intraPlaque Hemorrhage (SNAP) to detect the lipid-rich/necrotic core (LRNC), and develop a machine learning based algorithm to segment plaque components on SNAP images. METHODS: Sixty-eight patients (age: 58±9 years, 24 males) with carotid artery atherosclerotic plaque were imaged on a 3 T MR scanner with both traditional multi-contrast vessel wall MR sequences (TOF, T1W, and T2W) and 3D SNAP sequence. The manual segmentations of carotid plaque components including LRNC, intraplaque hemorrhage (IPH), calcification (CA) and fibrous tissue (FT) on traditional multi-contrast images were used as reference. By utilizing the intensity and morphological information from SNAP, a machine learning based two steps algorithm was developed to firstly identify LRNC (with or without IPH), CA and FT, and then segmented IPH from LRNC. Ten-fold cross-validation was used to evaluate the performance of proposed method. The overall pixel-wise accuracy, the slice-wise sensitivity & specificity & Youden's index, and the Pearson's correlation coefficient of the component area between the proposed method and the manual segmentation were reported. RESULTS: In the first step, all tested classifiers (Naive Bayes (NB), Support Vector Machine (SVM), Random Forest (RF), Gradient Boosting Decision Tree (GBDT) and Artificial Neural Network (ANN)) had overall pixel-wise accuracy higher than 0.88. For RF, GBDT and ANN classifiers, the correlation coefficients of areas were all higher than 0.82 (p < 0.001) for LRNC and 0.79 for CA (p < 0.001), and the Youden's indexes were all higher than 0.79 for LRNC and 0.76 for CA, which were better than that of NB and SVM. In the second step, the overall pixel-wise accuracy was higher than 0.78 for the five classifiers, and RF achieved the highest Youden's index (0.69) with the correlation coefficients as 0.63 (p < 0.001). CONCLUSIONS: The RF is the overall best classifier for our proposed method, and the feasibility of using SNAP to identify plaque components, including LRNC, IPH, CA, and FT has been validated. The proposed segmentation method using a single SNAP sequence might be a promising tool for atherosclerotic plaque components assessment.


Assuntos
Angiografia/métodos , Artérias Carótidas/diagnóstico por imagem , Hemorragia Cerebral/diagnóstico por imagem , Aprendizado de Máquina , Placa Aterosclerótica/diagnóstico por imagem , Idoso , Algoritmos , Teorema de Bayes , Calcinose/diagnóstico por imagem , Artéria Carótida Primitiva/diagnóstico por imagem , Estenose das Carótidas/diagnóstico por imagem , Meios de Contraste , Feminino , Humanos , Lipídeos , Masculino , Pessoa de Meia-Idade , Necrose , Placa Amiloide/diagnóstico por imagem , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
5.
Magn Reson Med ; 81(2): 1031-1043, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-30393892

RESUMO

PURPOSE: The aim of this study was to develop, test and validate a 3D free-breathing technique for simultaneous measurement of native myocardial T1 and T2 . METHODS: The proposed 3D technique acquires five fat-suppressed electrocardiogram-triggered respiratory navigator-gated spoiled gradient echo volumes in an interleaved manner. Four volumes are prepared using a combination of nonselective saturation and T2 preparation. One volume is acquired with fully recovered longitudinal magnetization for accuracy during parametric fitting. Performance of the technique was validated through numerical simulations, phantom experiments and in vivo experiments in 15 healthy human subjects. RESULTS: Simulations and phantom experiments show that the measured T1 and T2 are largely insensitive to heart rate. In vivo whole-heart maps with a voxel size of 1.5 × 1.5 × 16 mm3 were acquired without parallel imaging within ~ 8 min including respiratory gating efficiency. The in vivo parametric maps were homogeneous (coefficients of variation of left ventricle myocardium were 6.0% ± 0.8% and 10.2% ± 3.4% for T1 and T2 maps, respectively), with an average T1 value of 1470 ± 59.2 ms and T2 value of 41.6 ± 1.8 ms CONCLUSIONS: The proposed 3D technique allows for measurement of whole-heart T1 and T2 with preserved accuracy and precision in a single scan.


Assuntos
Coração/diagnóstico por imagem , Imageamento Tridimensional/métodos , Respiração , Adolescente , Adulto , Algoritmos , Técnicas de Imagem Cardíaca/métodos , Simulação por Computador , Feminino , Voluntários Saudáveis , Frequência Cardíaca , Humanos , Aumento da Imagem/métodos , Interpretação de Imagem Assistida por Computador/métodos , Masculino , Modelos Teóricos , Miocárdio/patologia , Imagens de Fantasmas , Reprodutibilidade dos Testes , Adulto Jovem
6.
Neuroimage ; 188: 302-308, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30553041

RESUMO

Reduction in cerebral blood flow (CBF), one of the major metrics for cerebral perfusion, is associated with many brain disorders. Therefore, early characterization of CBF prior to occurrence of symptoms is essential for prevention of cerebral ischemic events. We hypothesized that large artery atherosclerosis might be a potential indicator for decline in cerebral perfusion. The aim of this study was to investigate the relationship between large artery atherosclerosis and CBF in asymptomatic adults. A total of 134 asymptomatic subjects (mean age, 56.2 ±â€¯12.8 years; 54 males) were recruited and underwent magnetic resonance (MR) imaging for brain and intracranial and extracranial carotid arteries. Presence or absence of cerebrovascular atherosclerosis was determined on MR vessel wall images. The CBF was measured with pseudo-continuous arterial spin labeling (pCASL) imaging. The CBF values in internal carotid artery (ICA) (37.2 ±â€¯5.8 vs. 39.0 ±â€¯4.9 ml/100 g/min, P = 0.049) and vertebrobasilar artery (VA-BA) territories (42.0 ±â€¯6.8 vs. 44.8 ±â€¯7.0 ml/100 g/min, P = 0.023) were significantly reduced in subjects with cerebrovascular plaque compared to those without. Presence of cerebrovascular plaque was significantly associated with CBF of VA-BA territory before (odds ratio, 2.89; 95% confidence interval, 1.37-6.08; P = 0.005) and after adjusted for confounding factors including age, gender, body-mass-index, diabetes, systolic blood pressure, hyperlipidemia and history of cardiovascular disease (odds ratio, 2.76; 95% confidence interval, 1.18-6.46; P = 0.019). In conclusion, presence of cerebrovascular atherosclerosis is independently associated with reduction in CBF measured by pCASL in asymptomatic adults, suggesting that cerebrovascular large artery atherosclerosis might be an effective indicator for impairment of cerebral microcirculation hemodynamics.


Assuntos
Doenças das Artérias Carótidas/fisiopatologia , Circulação Cerebrovascular/fisiologia , Arteriosclerose Intracraniana/fisiopatologia , Imagem por Ressonância Magnética/métodos , Placa Aterosclerótica/fisiopatologia , Adulto , Idoso , Doenças das Artérias Carótidas/diagnóstico por imagem , Feminino , Humanos , Arteriosclerose Intracraniana/diagnóstico por imagem , Pessoa de Meia-Idade , Placa Aterosclerótica/diagnóstico por imagem , Marcadores de Spin
7.
J Cardiovasc Magn Reson ; 20(1): 64, 2018 09 17.
Artigo em Inglês | MEDLINE | ID: mdl-30220254

RESUMO

BACKGROUND: This study demonstrates a three-dimensional (3D) free-breathing native myocardial T1 mapping sequence at 3 T. METHODS: The proposed sequence acquires three differently T1-weighted volumes. The first two volumes receive a saturation pre-pulse with different recovery time. The third volume is acquired without magnetization preparation and after a significant recovery time. Respiratory navigator gating and volume-interleaved acquisition are adopted to mitigate misregistration. The proposed sequence was validated through simulation, phantom experiments and in vivo experiments in 12 healthy adult subjects. RESULTS: In phantoms, good agreement on T1 measurement was achieved between the proposed sequence and the reference inversion recovery spin echo sequence (R2 = 0.99). Homogeneous 3D T1 maps were obtained from healthy adult subjects, with a T1 value of 1476 ± 53 ms and a coefficient of variation (CV) of 6.1 ± 1.4% over the whole left-ventricular myocardium. The averaged septal T1 was 1512 ± 60 ms with a CV of 2.1 ± 0.5%. CONCLUSION: Free-breathing 3D native T1 mapping at 3 T is feasible and may be applicable in myocardial assessment. The proposed 3D T1 mapping sequence is suitable for applications in which larger coverage is desired beyond that available with single-shot parametric mapping, or breath-holding is unfeasible.


Assuntos
Coração/diagnóstico por imagem , Interpretação de Imagem Assistida por Computador/métodos , Imageamento Tridimensional/métodos , Imagem por Ressonância Magnética/métodos , Respiração , Função Ventricular Esquerda , Adulto , Estudos de Viabilidade , Feminino , Voluntários Saudáveis , Coração/fisiologia , Frequência Cardíaca , Humanos , Imagem por Ressonância Magnética/instrumentação , Masculino , Pessoa de Meia-Idade , Imagens de Fantasmas , Valor Preditivo dos Testes , Reprodutibilidade dos Testes , Adulto Jovem
8.
Magn Reson Med ; 79(2): 723-729, 2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-28480534

RESUMO

PURPOSE: Applications of intravoxel incoherent motion (IVIM) imaging in the brain are scarce, whereas it has been successfully applied in other organs with promising results. To better understand the cerebral IVIM signal, the diffusion properties of the arterial blood flow within different parts of the cerebral vascular tree (i.e., different generations of the branching pattern) were isolated and measured by employing an arterial spin labeling (ASL) preparation module before an IVIM readout. METHODS: ASL preparation was achieved by T1 -adjusted time-encoded pseudo-continuous ASL (te-pCASL). The IVIM readout module was achieved by introducing bipolar gradients immediately after the excitation pulse. The results of ASL-IVIM were compared with those of conventional IVIM to improve our understanding of the signal generation process of IVIM. RESULTS: The pseudo-diffusion coefficient D* as calculated from ASL-IVIM data was found to decrease exponentially for postlabeling delays (PLDs) between 883 ms and 2176 ms, becoming relatively stable for PLDs longer than 2176 ms. The fast compartment of the conventional IVIM-experiment shows comparable apparent diffusion values to the ASL signal with PLDs between 1747 ms and 2176 ms. At the longest PLDs, the observed D* values (4.0 ± 2.8 × 10-3 mm2 /s) are approximately 4.5 times higher than the slow compartment (0.90 ± 0.05 × 10-3 mm2 /s) of the conventional IVIM experiment. CONCLUSION: This study showed much more complicated diffusion properties of vascular signal than the conventionally assumed single D* of the perfusion compartment in the two-compartment model of IVIM (biexponential behavior). Magn Reson Med 79:723-729, 2018. © 2017 International Society for Magnetic Resonance in Medicine.


Assuntos
Encéfalo , Imagem por Ressonância Magnética Intervencionista/métodos , Processamento de Sinais Assistido por Computador , Adulto , Encéfalo/irrigação sanguínea , Encéfalo/diagnóstico por imagem , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Marcadores de Spin , Adulto Jovem
9.
J Cereb Blood Flow Metab ; 38(9): 1461-1480, 2018 09.
Artigo em Inglês | MEDLINE | ID: mdl-28598243

RESUMO

With the publication in 2015 of the consensus statement by the perfusion study group of the International Society for Magnetic Resonance in Medicine (ISMRM) and the EU-COST action 'ASL in dementia' on the implementation of arterial spin labelling MRI (ASL) in a clinical setting, the development of ASL can be considered to have become mature and ready for clinical prime-time. In this review article new developments and remaining issues will be discussed, especially focusing on quantification of ASL as well as on new technological developments of ASL for perfusion imaging and flow territory mapping. Uncertainty of the achieved labelling efficiency in pseudo-continuous ASL (pCASL) as well as the presence of arterial transit time artefacts, can be considered the main remaining challenges for the use of quantitative cerebral blood flow (CBF) values. New developments in ASL centre around time-efficient acquisition of dynamic ASL-images by means of time-encoded pCASL and diversification of information content, for example by combined 4D-angiography with perfusion imaging. Current vessel-encoded and super-selective pCASL-methodology have developed into easily applied flow-territory mapping methods providing relevant clinical information with highly similar information content as digital subtraction angiography (DSA), the current clinical standard. Both approaches seem therefore to be ready for clinical use.


Assuntos
Encéfalo/irrigação sanguínea , Angiografia Cerebral/métodos , Circulação Colateral/fisiologia , Imagem por Ressonância Magnética/métodos , Imagem de Perfusão/métodos , Circulação Cerebrovascular/fisiologia , Hemodinâmica/fisiologia , Humanos , Marcadores de Spin
10.
Magn Reson Med ; 79(4): 1922-1930, 2018 04.
Artigo em Inglês | MEDLINE | ID: mdl-28736949

RESUMO

PURPOSE: The aim of this study was to propose, optimize, and validate a pseudo-continuous arterial spin labeling (pCASL) sequence for simultaneous measurement of brain perfusion and labeling efficiency. METHODS: The proposed sequence incorporates the labeling efficiency measurement into the postlabeling delay period of a conventional perfusion pCASL sequence by using the time-encoding approach. In vivo validation experiments were performed on nine young subjects by comparing it to separate perfusion and labeling efficiency sequences. Sensitivity of the proposed combined sequence for measuring labeling efficiency changes was further addressed by varying the flip angles of the pCASL labeling radiofrequency pulses. RESULTS: The proposed combined sequence decreased the perfusion signal by ∼4% and a lower labeling efficiency (by ∼10%) was found as compared to the separate sequences. However, the temporal signal-noise-ratio of the perfusion signal remained unchanged. When the pCASL flip angle was decreased to a suboptimal setting, a strong correlation was found between the combined and the separate sequences for the relative change in pCASL perfusion signal as well as for the relative change in labeling efficiency. High correlation was also observed between relative changes in perfusion signal and the measured labeling efficiencies. CONCLUSION: The proposed sequence allows simultaneous measurement of brain perfusion and labeling efficiency with high time-efficiency at the price of only a small compromise in measurement accuracy. The additional labeling efficiency measurement can be used to facilitate qualitative interpretation of pCASL perfusion images. Magn Reson Med 79:1922-1930, 2018. © 2017 International Society for Magnetic Resonance in Medicine.


Assuntos
Artérias/diagnóstico por imagem , Encéfalo/diagnóstico por imagem , Circulação Cerebrovascular , Angiografia por Ressonância Magnética/métodos , Adulto , Feminino , Voluntários Saudáveis , Humanos , Interpretação de Imagem Assistida por Computador , Imagem por Ressonância Magnética , Masculino , Neuroimagem/métodos , Perfusão , Reprodutibilidade dos Testes , Razão Sinal-Ruído , Marcadores de Spin
11.
Neuroradiology ; 59(5): 485-490, 2017 May.
Artigo em Inglês | MEDLINE | ID: mdl-28357461

RESUMO

PURPOSE: Significant stenosis or occlusion in carotid arteries may lead to diffuse wall thickening (DWT) in the arterial wall of downstream. This study aimed to investigate the correlation between proximal internal carotid artery (ICA) steno-occlusive disease and DWT in ipsilateral petrous ICA. METHODS: Symptomatic patients with atherosclerotic stenosis (>0%) in proximal ICA were recruited and underwent carotid MR vessel wall imaging. The 3D motion sensitized-driven equilibrium prepared rapid gradient-echo (3D-MERGE) was acquired for characterizing the wall thickness and longitudinal extent of the lesions in petrous ICA and the distance from proximal lesion to the petrous ICA. The stenosis degree in proximal ICA was measured on the time-of-flight (TOF) images. RESULTS: In total, 166 carotid arteries from 125 patients (mean age 61.0 ± 10.5 years, 99 males) were eligible for final analysis and 64 showed DWT in petrous ICAs. The prevalence of severe DWT in petrous ICA was 1.4%, 5.3%, 5.9%, and 80.4% in ipsilateral proximal ICAs with stenosis category of 1%-49%, 50%-69%, 70%-99%, and total occlusion, respectively. Proximal ICA stenosis was significantly correlated with the wall thickness in petrous ICA (r = 0.767, P < 0.001). Logistic regression analysis showed that proximal ICA stenosis was independently associated with DWT in ipsilateral petrous ICA (odds ratio (OR) = 2.459, 95% confidence interval (CI) 1.896-3.189, P < 0.001]. CONCLUSION: Proximal ICA steno-occlusive disease is independently associated with DWT in ipsilateral petrous ICA.


Assuntos
Estenose das Carótidas/diagnóstico por imagem , Estenose das Carótidas/patologia , Angiografia por Ressonância Magnética/métodos , Feminino , Humanos , Imageamento Tridimensional , Masculino , Pessoa de Meia-Idade , Fatores de Risco
12.
Magn Reson Med ; 77(5): 1841-1852, 2017 05.
Artigo em Inglês | MEDLINE | ID: mdl-27174204

RESUMO

PURPOSE: Optimization and validation of a sequence for measuring the labeling efficiency of pseudocontinuous arterial spin labeling (pCASL) perfusion MRI. METHODS: The proposed sequence consists of a labeling module and a single slice Look-Locker echo planar imaging readout. A model-based algorithm was used to calculate labeling efficiency from the signal acquired from the main brain-feeding arteries. Stability of the labeling efficiency measurement was evaluated with regard to the use of cardiac triggering, flow compensation and vein signal suppression. Accuracy of the measurement was assessed by comparing the measured labeling efficiency to mean brain pCASL signal intensity over a wide range of flip angles as applied in the pCASL labeling. RESULTS: Simulations show that the proposed algorithm can effectively calculate labeling efficiency when correcting for T1 relaxation of the blood spins. Use of cardiac triggering and vein signal suppression improved stability of the labeling efficiency measurement, while flow compensation resulted in little improvement. The measured labeling efficiency was found to be linearly (R = 0.973; P < 0.001) related to brain pCASL signal intensity over a wide range of pCASL flip angles. CONCLUSION: The optimized labeling efficiency sequence provides robust artery-specific labeling efficiency measurement within a short acquisition time (∼30 s), thereby enabling improved accuracy of pCASL CBF quantification. Magn Reson Med 77:1841-1852, 2017. © 2016 International Society for Magnetic Resonance in Medicine Magn Reson Med 77:1841-1852, 2017. © 2016 International Society for Magnetic Resonance in Medicine.


Assuntos
Artérias/diagnóstico por imagem , Artérias Cerebrais/diagnóstico por imagem , Marcadores de Spin , Adulto , Algoritmos , Encéfalo/irrigação sanguínea , Circulação Cerebrovascular , Simulação por Computador , Imagem Ecoplanar , Feminino , Voluntários Saudáveis , Coração/diagnóstico por imagem , Humanos , Aumento da Imagem/métodos , Interpretação de Imagem Assistida por Computador/métodos , Imageamento Tridimensional/métodos , Angiografia por Ressonância Magnética/métodos , Masculino , Tomografia por Emissão de Pósitrons , Processamento de Sinais Assistido por Computador
13.
J Magn Reson Imaging ; 44(6): 1592-1599, 2016 12.
Artigo em Inglês | MEDLINE | ID: mdl-27249041

RESUMO

PURPOSE: Basilar artery (BA) atherosclerosis is an important cause of perforator stroke in the brainstem due to plaque involvement of the perforator ostia in BA dorsal or lateral walls. Therefore, to acquire information on plaque distribution is important to better understand and prevent the perforator stroke. This study aimed to comprehensively evaluate BA plaque distribution with 3D magnetic resonance imaging (MRI) vessel wall imaging. MATERIALS AND METHODS: Consecutive patients with cerebrovascular symptoms and stenosis or irregular luminal surface of BA were recruited and underwent BA 3D proton density-weighted volume isotropic turbo spin echo acquisition (VISTA) imaging at 3T. The cross-sectional and longitudinal distribution of BA plaque were analyzed with a custom-developed tool. RESULTS: In all, 85 BA plaques were detected in 61 recruited patients. For cross-sectional distribution, the prevalence of plaque involvement in the ventral, left, dorsal, and right quadrant of BA wall was 74.1%, 70.6%, 67.1%, and 62.4%, respectively. Of the 85 plaques, 17.7% involved one quadrant and 82.3% involved two or more quadrants. The most severe plaque region was more commonly situated at lateral walls (66.1%) as compared to ventral (23.2%, P < 0.001) and dorsal walls (10.6%, P < 0.001). Longitudinally, plaques were more frequently found to occur at BA segment distal than proximal to anterior inferior cerebellar artery (AICA) (63.5% vs. 36.5%). CONCLUSION: Taking advantage of 3D MR vessel wall imaging, BA plaques were found to more likely affect lateral walls and form in BA distal to AICA, where most perforators originate, suggesting that it might be useful to characterize BA plaque distribution before aggressive treatment for prevention of perforator stroke. J. Magn. Reson. Imaging 2016;44:1592-1599.


Assuntos
Artéria Basilar/diagnóstico por imagem , Imageamento Tridimensional/métodos , Arteriosclerose Intracraniana/diagnóstico por imagem , Angiografia por Ressonância Magnética/métodos , Insuficiência Vertebrobasilar/diagnóstico por imagem , Artéria Basilar/patologia , Feminino , Humanos , Aumento da Imagem/métodos , Interpretação de Imagem Assistida por Computador/métodos , Arteriosclerose Intracraniana/patologia , Masculino , Pessoa de Meia-Idade , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Insuficiência Vertebrobasilar/patologia
14.
J Magn Reson Imaging ; 44(5): 1270-1276, 2016 11.
Artigo em Inglês | MEDLINE | ID: mdl-27079951

RESUMO

PURPOSE: To evaluate the usefulness of quantitative characteristics of morphology and signal intensity of arterial wall measured by 3D multicontrast magnetic resonance vessel wall imaging (MRVWI) in identification of carotid early atherosclerosis (CEAS). MATERIALS AND METHODS: In all, 61 older subjects (mean age 71.8 ± 5.6 years old; 25 males) without cardiovascular symptoms in the last 6 months were recruited. The carotid arteries without advanced plaque features on 3.0T MRI were included for analysis. Ultrasound imaging was used as a reference to identify CEAS. The morphological parameters including lumen area (LA), wall area (WA), wall thickness (WT), and normalized wall index (NWI = WA/[WA+LA] × 100%) and the signal intensity on 3.0T MR T2 -weighted images (T2 SI) of the carotid arterial wall were measured. Three regression models were built to identify CEAS with the following parameters: Model 1 with both morphological and T2 SI parameters; Model 2 with T2 SI parameters; and Model 3 with morphological parameters. All models were adjusted for age and sex. Area under the curve (AUC) was calculated to validate models. RESULTS: Of the 86 carotid arteries without advanced plaques, 47 (54.7%) were found to have early plaques determined by ultrasound. Among three regression models, Model 1 showed the highest AUC values in identifying CEAS (left: AUC = 0.856, P < 0.001; right: AUC = 0.867, P < 0.001), followed by Model 2 (left: AUC = 0.843, P < 0.001; right: AUC = 0.798, P = 0.001), and Model 3 (left: AUC = 0.790, P = 0.002; right: AUC = 0.806, P < 0.001). CONCLUSION: The combination of morphology and normalized T2 SI of arterial wall measured by MRVWI is more effective than each characteristic alone in identification of CEAS. J. Magn. Reson. Imaging 2016;44:1270-1276.


Assuntos
Algoritmos , Doenças das Artérias Carótidas/diagnóstico por imagem , Doenças das Artérias Carótidas/patologia , Diagnóstico Precoce , Interpretação de Imagem Assistida por Computador/métodos , Imageamento Tridimensional/métodos , Imagem por Ressonância Magnética/métodos , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Aumento da Imagem/métodos , Masculino , Pessoa de Meia-Idade , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
15.
J Magn Reson Imaging ; 41(4): 1138-42, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-24700507

RESUMO

PURPOSE: To investigate the correlations of arterial distensibility between carotid arteries and abdominal aorta by MR. MATERIALS AND METHODS: Twenty eight asymptomatic old subjects (71.4 ± 6.7 years; 14 males) and 20 healthy young subjects (23.5 ± 1.0 years; 10 males) were imaged with electrocardiograph-triggered balanced turbo field echo sequence sequence. Arterial distensibility was calculated as the relative lumen area change against unit blood pressure change and its relationship between carotid arteries and abdominal aorta was determined. RESULTS: The arterial distensibility in old subjects was significantly smaller than that in young subjects for left carotid artery (19.0 ± 6.6 × 10(-3) /kpa versus 30.9 ± 6.5 × 10(-3) /kpa), right carotid artery (16.7 ± 6.1 × 10(-3) /kpa versus 28.6 ± 9.3 × 10(-3) /kpa), and abdominal aorta (14.3 ± 5.5 × 10(-3) /kpa versus 37.5 ± 8.8 × 10(-3) /kpa), respectively (all P < 0.001). In both age groups, distensibility of the abdominal aorta was strongly correlated with that of the left carotid artery (old age group: r = 0.553; P = 0.004; young age group: r = 0.487; P = 0.029) but not with that of the right carotid artery (old age group: r = 0.371; P = 0.062; young age group: r = 0.189; P = 0.424). CONCLUSION: The distensibility of abdominal aorta is much more strongly associated with that of the left carotid artery compared with that of the right carotid artery.


Assuntos
Envelhecimento/fisiologia , Aorta Abdominal/fisiologia , Artérias Carótidas/fisiologia , Técnicas de Imagem por Elasticidade/métodos , Angiografia por Ressonância Magnética/métodos , Rigidez Vascular/fisiologia , Idoso , Algoritmos , Aorta Abdominal/anatomia & histologia , Artérias Carótidas/anatomia & histologia , Feminino , Humanos , Aumento da Imagem/métodos , Interpretação de Imagem Assistida por Computador/métodos , Masculino , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Adulto Jovem
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