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Henrik Haraldsson Michael Hope Gabriel Acevedo-Bolton Elaine Tseng Xiaodong Zhong Frederick H Epstein Liang Ge David Saloner 《Journal of cardiovascular magnetic resonance》2014,16(1):1-8
Background
Vessel diameter is the principal imaging parameter assessed clinically for aortic disease, but adverse events can occur at normal diameters. Aortic stiffness has been studied as an additional imaging-based risk factor, and has been shown to be an independent predictor of cardiovascular morbidity and all-cause mortality. Reports suggest that some aortic pathology is asymmetric around the vessel circumference, a feature which would not be identified with current imaging approaches. We propose that this asymmetry may be revealed using Displacement Encoding with Stimulated Echoes (DENSE). The objective of this study is to investigate the feasibility of assessing asymmetric stretch in healthy and diseased ascending aortas using DENSE.Methods
Aortic wall displacement was assessed with DENSE cardiovascular magnetic resonance (CMR) in 5 volunteers and 15 consecutive patients. Analysis was performed in a cross-sectional plane through the ascending aorta at the pulmonary artery. Displacement data was used to determine the wall stretch between the expanded and resting states of the aorta, in four quadrants around the aortic circumference.Results
Analysis of variance (ANOVA) did not only show significant differences in stretch between groups of volunteers (p < 0.001), but also significant differences in stretch along the circumference of the aorta (p < 0.001), indicating an asymmetric stretch pattern. Furthermore, there is a significant difference in the asymmetry between volunteers and different groups of patients (p < 0.01).Conclusions
Evaluation of asymmetric stretch is feasible in the ascending aorta with DENSE CMR. Clear differences in stretch are seen between patients and volunteers, with asymmetric patterns demonstrated around the aortic circumference. 相似文献3.
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Li Feng Robert Donnino James Babb Leon Axel Daniel Kim 《Magnetic resonance in medicine》2009,62(3):682-690
Quantitative assessment of regional cardiac function can improve the accuracy of detecting wall motion abnormalities due to heart disease. While recently developed fast cine displacement‐encoded with stimulated echoes (DENSE) MRI is a promising modality for the quantification of regional myocardial function, it has not been validated for clinical applications. The purpose of this study, therefore, was to validate the accuracy of fast cine DENSE MRI with numerical simulation and in vivo experiments. A numerical phantom was generated to model physiologically relevant deformation of the heart, and the accuracy of fast cine DENSE was evaluated against the numerical reference. For in vivo validation, 12 controls and 13 heart‐disease patients were imaged using both fast cine DENSE and myocardial tagged MRI. Numerical simulation demonstrated that the echo‐combination DENSE reconstruction method is relatively insensitive to clinically relevant resonance frequency offsets. The strain measurements by fast cine DENSE and the numerical reference were strongly correlated and in excellent agreement (mean difference = 0.00; 95% limits of agreement were 0.01 and ?0.02). The strain measurements by fast cine DENSE and myocardial tagged MRI were strongly correlated (correlation coefficient = 0.92) and in good agreement (mean difference = 0.01; 95% limits of agreement were 0.07 and ?0.04). Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc. 相似文献
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Displacement-encoded imaging with stimulated echoes (DENSE) and harmonic phase imaging (HARP) employ 1-1 spatial modulation of magnetization to cosine modulate the longitudinal magnetization as a function of position at end diastole. Later in the cardiac cycle they sample the cosine-modulated signal and compute myocardial strain from the signal phase. The sampled signal generally includes three distinct echoes: 1) a displacement-encoded stimulated echo, 2) the complex conjugate of the displacement-encoded echo, and 3) an echo arising from T1 relaxation. If the T1-relaxation and complex conjugate echoes are suppressed, then a phase image representing just the displacement-encoded echo can be reconstructed. In the present study, the use of cosine and sine modulation to eliminate (CANSEL) the T1-relaxation and complex conjugate echoes was investigated. With the use of CANSEL, it was demonstrated that DENSE accurately measures through-plane as well as in-plane components of tissue motion. Also, DENSE with CANSEL artifact suppression can provide increased signal-to-noise ratio (SNR) secondary to reduced intravoxel dephasing by using relatively low displacement-encoding frequencies. For applications that employ DENSE imaging with multiple acquisitions, the CANSEL technique can suppress artifact-generating echoes without placing constraints on the displacement-encoding frequency and direction. 相似文献
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Gregory J Wehner Jonathan D Suever Christopher M Haggerty Linyuan Jing David K Powell Sean M Hamlet Jonathan D Grabau Walter Dimitri Mojsejenko Xiaodong Zhong Frederick H Epstein Brandon K Fornwalt 《Journal of cardiovascular magnetic resonance》2015,17(1)
Background
Displacement Encoding with Stimulated Echoes (DENSE) encodes displacement into the phase of the magnetic resonance signal. Due to the stimulated echo, the signal is inherently low and fades through the cardiac cycle. To compensate, a spiral acquisition has been used at 1.5T. This spiral sequence has not been validated at 3T, where the increased signal would be valuable, but field inhomogeneities may result in measurement errors. We hypothesized that spiral cine DENSE is valid at 3T and tested this hypothesis by measuring displacement errors at both 1.5T and 3T in vivo.Methods
Two-dimensional spiral cine DENSE and tagged imaging of the left ventricle were performed on ten healthy subjects at 3T and six healthy subjects at 1.5T. Intersection points were identified on tagged images near end-systole. Displacements from the DENSE images were used to project those points back to their origins. The deviation from a perfect grid was used as a measure of accuracy and quantified as root-mean-squared error. This measure was compared between 3T and 1.5T with the Wilcoxon rank sum test. Inter-observer variability of strains and torsion quantified by DENSE and agreement between DENSE and harmonic phase (HARP) were assessed by Bland-Altman analyses. The signal to noise ratio (SNR) at each cardiac phase was compared between 3T and 1.5T with the Wilcoxon rank sum test.Results
The displacement accuracy of spiral cine DENSE was not different between 3T and 1.5T (1.2 ± 0.3 mm and 1.2 ± 0.4 mm, respectively). Both values were lower than the DENSE pixel spacing of 2.8 mm. There were no substantial differences in inter-observer variability of DENSE or agreement of DENSE and HARP between 3T and 1.5T. Relative to 1.5T, the SNR at 3T was greater by a factor of 1.4 ± 0.3.Conclusions
The spiral cine DENSE acquisition that has been used at 1.5T to measure cardiac displacements can be applied at 3T with equivalent accuracy. The inter-observer variability and agreement of DENSE-derived peak strains and torsion with HARP is also comparable at both field strengths. Future studies with spiral cine DENSE may take advantage of the additional SNR at 3T. 相似文献7.
Michaela Soellinger Andrea K. Rutz Sebastian Kozerke Peter Boesiger 《Magnetic resonance in medicine》2009,61(1):153-162
Pulsatile brain motion is considered to be an important mechanical link between blood and cerebrospinal fluid (CSF) dynamics. Like many severe brain diseases, different types of hydrocephalus are associated with impairment of these dynamics. In this work a cine displacement‐encoded imaging method employing stimulated echoes (DENSE) and a three‐dimensional (3D) segmented echo‐planar imaging (EPI) readout for brain motion measurements in all three spatial directions is presented. Displacement‐encoded data sets of 12 healthy volunteers were analyzed with respect to reproducibility, periodicity, and intra‐ as well as intersubject physiological consistency. In addition, displacement values were compared with data derived from phase‐contrast (PC) velocity measurements in a subset of all measured subjects. Using DENSE, displacements as low as 0.01 mm could be detected and observation of the 3D pulse pressure wave propagation was possible. Among other parameters, peak displacements in the central brain regions were measured: feet–head (FH): thalamus (0.13 ± 0.01 mm); right–left (RL): thalamus (0.06 ± 0.01 mm); and anterior–posterior (AP): caudate nucleus (0.05 ± 0.01 mm). Magn Reson Med 61:153–162, 2009. © 2008 Wiley‐Liss, Inc. 相似文献
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Mixed echo train acquisition displacement encoding with stimulated echoes (meta-DENSE) is a phase-based displacement mapping technique suitable for imaging myocardial function. This method has been optimized for use with patients who have a history of myocardial infarction. The total scan time is 12-14 heartbeats for an in-plane resolution of 2.8 x 2.8 mm2. Myocardial strain is mapped at this resolution with an accuracy of 2% strain in vivo. Compared to standard stimulated echo (STE) methods, both data acquisition speed and resolution are improved with inversion-recovery FID suppression and the meta-DENSE readout scheme. Data processing requires minimal user intervention and provides a rapid quantitative feedback on the MRI scanner for evaluating cardiac function. Published 2001 Wiley-Liss, Inc. 相似文献
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Daniel A Auger Xiaodong Zhong Frederick H Epstein Ernesta M Meintjes Bruce S Spottiswoode 《Journal of cardiovascular magnetic resonance》2014,16(1):8