High-Resolution Strain Analysis of the Human Heart with Fast-DENSE

doi:10.1006/jmre.1999.1821

Journal of Magnetic Resonance

Volume 140, Issue 1, September 1999, Pages 41-57

https://doi.org/10.1006/jmre.1999.1821 Get rights and content

Abstract

Single breath-hold displacement data from the human heart were acquired with fast-DENSE (fast displacement encoding with stimulated echoes) during systolic contraction at 2.5 × 2.5 mm in-plane resolution. Encoding strengths of 0.86–1.60 mm/π were utilized in order to extend the dynamic range of the phase measurements and minimize effects of physiologic and instrument noise. The noise level in strain measurements for both contraction and dilation corresponded to a strain value of 2.8%. In the human heart, strain analysis has sufficient resolution to reveal transmural variation across the left ventricular wall. Data processing required minimal user intervention and provided a rapid quantitative feedback. The intrinsic temporal integration of fast-DENSE achieves high accuracy at the expense of temporal resolution.

References (25)

P.M. Pattynama et al.
Evaluation of cardiac function with magnetic resonance imaging
Am. Heart J.
(1994)
P.R. Moran
A flow velocity zeugmatographic interlace for NMR imaging in humans
Magn. Reson. Imaging
(1982)
P.F. Castro et al.
Evaluation of hibernating myocardium in patients with ischemic heart disease
Am. J. Med.
(1998)
T.G. Reese et al.
Measuring diffusion in the presence of material strain
J. Magn. Reson. B
(1996)
A.H. Aletras et al.
Displacement encoding with stimulated echoes in cardiac functional MRI
J. Magn. Reson.
(1999)
E. McVeigh
Regional myocardial function
Cardiol. Clin.
(1998)
A.A. Young et al.
Three-dimensional left ventricular deformation in hypertrophic cardiomyopathy
Circulation
(1994)
A.A. Young et al.
Right ventricular midwall surface motion and deformation using magnetic resonance tagging
Am. J. Physiol.
(1996)
A.A. Young et al.
Three-dimensional motion and deformation of the heart wall: Estimation with spatial modulation of magnetization—A model-based approach
Radiology
(1992)
W.J.J. Rogers et al.
Quantification of and correction for left ventricular systolic long-axis shortening by magnetic resonance tissue tagging and slice isolation
Circulation
(1991)

E.R. McVeigh

Imaging asynchronous mechanical activation of the paced heart with tagged MRI

Magn. Reson. Med.

(1998)

M. Kass et al.

Snakes: Active contour models

Int. J. Comp. Vis.

(1987)

Cited by (100)

Strategies for body-conformable electronics
2022, Matter
Advances in flexible and stretchable electronics have enabled an unprecedented level of coupling between electronics and bio-tissues by overcoming obstacles associated with the bio-tissues’ curvilinearity, softness, deformability, and wetness. This review begins by detailing the outstanding challenges in achieving body-conformable electronics stemming from the disparate properties of bio-tissues and man-made materials and the complexity of their interfaces. Given tissue properties, an existing mechanics model has revealed how device softness and interfacial adhesion govern the bio-electronics conformability. Therefore, we first summarize methods for improving the mechanical compliance of electronics through both material engineering and structural design. Then, we discuss strategies to enhance bio-electronics adhesion in both dry and wet environments. We point out that innovative bio-electronics integration procedures also have a significant impact on bio-electronics conformability. We conclude by providing an outlook into future opportunities and proposing a holistic approach to strategizing body-conformable electronics.
Development, calibration, and testing of 3D amplified MRI (aMRI) for the quantification of intrinsic brain motion
2021, Brain Multiphysics
Citation Excerpt :
This method is often used to analyze the brain’s deformation during a mild acceleration in vivo [13], however, the brain’s intrinsic motion is very small (sub-voxel level); therefore, tagged MRI cannot accurately measure its motion. Other methods such as displacement encoded imaging with stimulated echoes (DENSE) MRI, have also shown promising results in quantifying the cardiac-induced brain motion [17–20]. DENSE MRI, combined with PC-MRI demonstrated a direct correlation between the brain’s volumetric strain and the CSF stroke volumes [7].
Microvascular blood volume pulsations, combined with CSF circulation result in subtle deformation of the brain during each heartbeat. To visualize and quantify these small deformations, an image processing technique called amplified MRI (aMRI) was recently introduced. aMRI, however, is unable to visualize the 3-directional deformation of the human brain, which is caused by the physiological flow and its biomechanical coupling with the brain. Addressing this issue, we extended 2D aMRI to 3D, which allows visualization of the subtle motion in 3-directions. First, we validated 3D aMRI’s ability to measure out-of-plane motion while simultaneously increasing SNR in digital phantoms mimicking the brain’s deformation. We then applied 2D and 3D aMRI to 3D cine MRI of 6 healthy subjects and found approximately 80% higher temporal SNR in the 3D aMRI outputs with SNR $= 26.8 \pm 8.3$ compared to the 2D aMRI with SNR $= 15.1 \pm 2.6$ ( $p < 0.01$ ). 3D displacement maps and their dominant modeshapes were extracted, which demonstrated physiologically meaningful patterns of motion in response to heart pulsatility and CSF circulation. We observed the peak superior-inferior displacement near the pons and midbrain. Peak medial-lateral and anterior-posterior displacement were observed close to the $3^{r d}$ and lateral ventricles. Interestingly, the modeshapes showed an almost symmetrical expansion of the brain with $33 % \pm 4 %,$ $38 % \pm 4 %,$ and $29 % \pm 7 %$ of the deformation being predominantly towards superior-inferior, anterior-posterior, and medial-lateral, respectively ( $p < 0.01$ ). These preliminary results hint at 3D aMRI’s versatility and translatability for providing novel biomechanical imaging markers, which could simplify diagnostics and enable a deeper understanding of the biomechanics of a wide-range of pathophysiological conditions.
The brain has very soft material properties and is under constant deformation as a result of physiological flow and its biomechanical coupling with the tissue. In this work, a novel image processing algorithm called 3D aMRI is introduced which allows visualization and quantification of this very subtle motion. After validation of the algorithm using digital phantom models, 3D aMRI was applied to in vivo 3D cine MRI data. This allowed measurement of the brain’s subtle deformation as a response of heart pulsatility and CSF circulation, which might hold essential information regarding the physiological state of the brain tissue. 3D aMRI is a post-processing algorithm carried out on standard imaging data. We believe that due to its versatility and translatability, it could simplify diagnostics and enable a deeper understanding of the biomechanics of a wide range of pathophysiological conditions.
Impaired right ventricular contractile function in childhood obesity and its association with right and left ventricular changes: A cine DENSE cardiac magnetic resonance study
2017, Journal of Cardiovascular Magnetic Resonance
Pediatric obesity is a growing public health problem, which is associated with increased risk of cardiovascular disease and premature death. Left ventricular (LV) remodeling (increased myocardial mass and thickness) and contractile dysfunction (impaired longitudinal strain) have been documented in obese children, but little attention has been paid to the right ventricle (RV). We hypothesized that obese/overweight children would have evidence of RV remodeling and contractile dysfunction.
One hundred and three children, ages 8–18 years, were prospectively recruited and underwent cardiovascular magnetic resonance (CMR), including both standard cine imaging and displacement encoding with stimulated echoes (DENSE) imaging, which allowed for quantification of RV geometry and function/mechanics. RV free wall longitudinal strain was quantified from the end-systolic four-chamber DENSE image. Linear regression was used to quantify correlations of RV strain with LV strain and measurements of body composition (adjusted for sex and height). Analysis of variance was used to study the relationship between RV strain and LV remodeling types (concentric remodeling, eccentric/concentric hypertrophy).
The RV was sufficiently visualized with DENSE in 70 (68%) subjects, comprising 36 healthy weight (13.6 ± 2.7 years) and 34 (12.1 ± 2.9 years) obese/overweight children. Obese/overweight children had a 22% larger RV mass index (8.2 ± 0.9 vs 6.7 ± 1.1 g/m^2.7, p < 0.001) compared to healthy controls. RV free wall longitudinal strain was impaired in obese/overweight children (−16 ± 4% vs −19 ± 5%, p = 0.02). Ten (14%) out of 70 children had LV concentric hypertrophy, and these children had the most impaired RV longitudinal strain compared to those with normal LV geometry (−13 ± 4% vs −19 ± 5%, p = 0.002). RV longitudinal strain was correlated with LV longitudinal strain (r = 0.34, p = 0.004), systolic blood pressure (r = 0.33, p = 0.006), as well as BMI z-score (r = 0.28, p = 0.02), waist (r = 0.31, p = 0.01), hip (r = 0.40, p = 0.004) and abdominal (r = 0.38, p = 0.002) circumference, height and sex adjusted.
Obese/overweight children have evidence of RV remodeling (increased RV mass) and RV contractile dysfunction (impaired free wall longitudinal strain). Moreover, RV longitudinal strain correlates with LV longitudinal strain, and children with LV concentric hypertrophy show the most impaired RV function. These results suggest there may be a common mechanism underlying both remodeling and dysfunction of the left and right ventricles in obese/overweight children.
Using a respiratory navigator significantly reduces variability when quantifying left ventricular torsion with cardiovascular magnetic resonance
2017, Journal of Cardiovascular Magnetic Resonance
Left ventricular (LV) torsion is an important indicator of cardiac function that is limited by high inter-test variability (50% of the mean value). We hypothesized that this high inter-test variability is partly due to inconsistent breath-hold positions during serial image acquisitions, which could be significantly improved by using a respiratory navigator for cardiovascular magnetic resonance (CMR) based quantification of LV torsion.
We assessed respiratory-related variability in measured LV torsion with two distinct experimental protocols. First, 17 volunteers were recruited for CMR with cine displacement encoding with stimulated echoes (DENSE) in which a respiratory navigator was used to measure and then enforce variability in end-expiratory position between all LV basal and apical acquisitions. From these data, we quantified the inter-test variability of torsion in the absence and presence of enforced end-expiratory position variability, which established an upper bound for the expected torsion variability. For the second experiment (in 20 new, healthy volunteers), 10 pairs of cine DENSE basal and apical images were each acquired from consecutive breath-holds and consecutive navigator-gated scans (with a single acceptance position). Inter-test variability of torsion was compared between the breath-hold and navigator-gated scans to quantify the variability due to natural breath-hold variation. To demonstrate the importance of these variability reductions, we quantified the reduction in sample size required to detect a clinically meaningful change in LV torsion with the use of a respiratory navigator.
The mean torsion was 3.4 ± 0.2°/cm. From the first experiment, enforced variability in end-expiratory position translated to considerable variability in measured torsion (0.56 ± 0.34°/cm), whereas inter-test variability with consistent end-expiratory position was 57% lower (0.24 ± 0.16°/cm, p < 0.001). From the second experiment, natural respiratory variability from consecutive breath-holds translated to a variability in torsion of 0.24 ± 0.10°/cm, which was significantly higher than the variability from navigator-gated scans (0.18 ± 0.06°/cm, p = 0.02). By using a respiratory navigator with DENSE, theoretical sample sizes were reduced from 66 to 16 and 26 to 15 as calculated from the two experiments.
A substantial portion (22-57%) of the inter-test variability of LV torsion can be reduced by using a respiratory navigator to ensure a consistent breath-hold position between image acquisitions.
Magnetic resonance imaging of mechanical deformations
2016, Magnetic Resonance Imaging
A method for magnetic resonance imaging of mechanical deformations is presented. The method utilizes an MRI compatible device for inducing elastic deformations of a sample and a modified spin-echo imaging sequence with two position-encoding gradients added to the sequence symmetrically to the RF refocusing pulse. At the end of the first position-encoding gradient pulse, a sample deformation was induced by the deformational device, which applied a force to a plastic rod embedded in a gelatin cylindrical sample. The sample had to withstand repeated elastic deformations. Sample displacements up to 400 μm were encoded in the image signal phase by the use of position-encoding gradients. Images of different displacement components were acquired first by the use of position-encoding gradients in different directions and then processed by the 2D phase unwrap algorithm. Finally, images of normal and shear strain distribution were calculated from the displacement images. The obtained displacement and strain images enabled clear visualization of deformations and their extent in the sample with the displacement detection threshold in the range 0.3–0.6 μm, depending on the image echo time. The results of displacements were verified also by a DANTE tagging method and by an optical method. The presented method enables studying of various types of deformations in different soft materials as well as dynamic response of deformations to different stress functions (static, oscillatory, pulsed…).
2D cine DENSE with low encoding frequencies accurately quantifies cardiac mechanics with improved image characteristics
2015, Journal of Cardiovascular Magnetic Resonance
Displacement Encoding with Stimulated Echoes (DENSE) encodes displacement into the phase of the magnetic resonance signal. The encoding frequency (k_e) maps the measured phase to tissue displacement while the strength of the encoding gradients affects image quality. 2D cine DENSE studies have used a k_e of 0.10 cycles/mm, which is high enough to remove an artifact-generating echo from k-space, provide high sensitivity to tissue displacements, and dephase the blood pool. However, through-plane dephasing can remove the unwanted echo and dephase the blood pool without relying on high k_e. Additionally, the high sensitivity comes with the costs of increased phase wrapping and intra-voxel dephasing. We hypothesized that k_e below 0.10 cycles/mm can be used to improve image characteristics and provide accurate measures of cardiac mechanics.
Spiral cine DENSE images were obtained for 10 healthy subjects and 10 patients with a history of heart disease on a 3 T Siemens Trio. A mid-ventricular short-axis image was acquired with different k_e: 0.02, 0.04, 0.06, 0.08, and 0.10 cycles/mm. Peak twist, circumferential strain, and radial strain were compared between acquisitions employing different k_e using Bland-Altman analyses and coefficients of variation. The percentage of wrapped pixels in the phase images at end-systole was calculated for each k_e. The dephasing of the blood signal and signal to noise ratio (SNR) were also calculated and compared.
Negligible differences were seen in strains and twist for all k_e between 0.04 and 0.10 cycles/mm. These differences were of the same magnitude as inter-test differences. Specifically, the acquisitions with 0.04 cycles/mm accurately quantified cardiac mechanics and had zero phase wrapping. Compared to 0.10 cycles/mm, the acquisitions with 0.04 cycles/mm had 9 % greater SNR and negligible differences in blood pool dephasing.
For 2D cine DENSE with through-plane dephasing, the encoding frequency can be lowered to 0.04 cycles/mm without compromising the quantification of twist or strain. The amount of wrapping can be reduced with this lower value to greatly simplify the input to unwrapping algorithms. The strain and twist results from studies using different encoding frequencies can be directly compared.

View all citing articles on Scopus

View full text

Regular ArticleHigh-Resolution Strain Analysis of the Human Heart with Fast-DENSE

Abstract

Am. Heart J.

Magn. Reson. Imaging

Am. J. Med.

J. Magn. Reson. B

J. Magn. Reson.

Cardiol. Clin.

Three-dimensional left ventricular deformation in hypertrophic cardiomyopathy

Circulation

Right ventricular midwall surface motion and deformation using magnetic resonance tagging

Am. J. Physiol.

Three-dimensional motion and deformation of the heart wall: Estimation with spatial modulation of magnetization—A model-based approach

Radiology

Quantification of and correction for left ventricular systolic long-axis shortening by magnetic resonance tissue tagging and slice isolation

Circulation

Imaging asynchronous mechanical activation of the paced heart with tagged MRI

Magn. Reson. Med.

Snakes: Active contour models

Int. J. Comp. Vis.

Regular Article
High-Resolution Strain Analysis of the Human Heart with Fast-DENSE