Abstract
BackgroundDisplacement encoded Cardiovascular MR (CMR) can provide high spatial resolution measurements of three-dimensional (3D) Lagrangian displacement. Spatial gradients of the Lagrangian displacement field are used to measure regional myocardial strain. In general, adjacent parallel slices are needed in order to calculate the spatial gradient in the through-slice direction. This necessitates the acquisition of additional data and prolongs the scan time. The goal of this study is to define an analytic solution that supports the reconstruction of the out-of-plane components of the Lagrangian strain tensor in addition to the in-plane components from a single-slice displacement CMR dataset with high spatio-temporal resolution. The technique assumes incompressibility of the myocardium as a physical constraint.ResultsThe feasibility of the method is demonstrated in a healthy human subject and the results are compared to those of other studies. The proposed method was validated with simulated data and strain estimates from experimentally measured DENSE data, which were compared to the strain calculation from a conventional two-slice acquisition.ConclusionThis analytical method reduces the need to acquire data from adjacent slices when calculating regional Lagrangian strains and can effectively reduce the long scan time by a factor of two.
Highlights
The left ventricular deformation associated with the pumping of blood from the heart is known to be complex [1]
Cardiovascular MR (CMR) phase contrast (PC) [3,4], tissue tagging [5,6], HARP [7], and DENSE [8] have arisen as powerful techniques for encoding cardiac motion in a CMR exam and each has specific advantages and disadvantages
DENSE displacement encoding is similar in principle to the PC velocityencoding method in that the motion components of small tissue volumes are encoded in the phase image at every image pixel location [9]; the number of measures across the LV wall is typically higher than the number of tags across the wall in a tagging experiment
Summary
The left ventricular deformation associated with the pumping of blood from the heart is known to be complex [1]. It is known that there are significant regional variations in the time course, magnitude, and spatial pattern of deformation within the ventricular wall [2]. In the course of heart failure and other cardiac diseases, wall motion abnormalities become very pronounced and deviate from the normal, healthy function of the myocardium. It is of significant clinical interest to quantify these regional wall motion abnormalities with high temporal and spatial resolution and derive indices of the nature and extent of cardiac dysfunction to better inform clinical decision-making. Displacement encoded Cardiovascular MR (CMR) can provide high spatial resolution measurements of three-dimensional (3D) Lagrangian displacement. Adjacent parallel slices are needed in order to calculate the spatial gradient in the through-slice direction This necessitates the acquisition of additional data and prolongs the scan time. The technique assumes incompressibility of the myocardium as a physical constraint
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