Accuracy of cardiac‐induced brain motion measurement using displacement‐encoding with stimulated echoes (DENSE) magnetic resonance imaging (MRI): A phantom study

Abstract

The goal of this study was to determine the accuracy of displacementencoding with stimulated echoes (DENSE) MRI in a tissue motion phantom with displacements representative of those observed in human brain tissue. Methods: The phantom was comprised of a plastic shaft rotated at a constant speed. The rotational motion was converted to a vertical displacement through a camshaft. The phantom generated repeatable cyclical displacement waveforms with a peak displacement ranging from 92 µm to 1.04 mm at 1-Hz frequency. The surface displacement of the tissue was obtained using a laser Doppler vibrometer (LDV) before and after the DENSE MRI scans to check for repeatability. The accuracy of DENSE MRI displacement was assessed by comparing the laser Doppler vibrometer and DENSE MRI waveforms. Results: Laser Doppler vibrometer measurements of the tissue motion demonstrated excellent cycle-to-cycle repeatability with a maximum root mean square error of 9 µm between the ensemble-averaged displacement waveform and the individual waveforms over 180 cycles. The maximum difference between DENSE MRI and the laser Doppler vibrometer waveforms ranged from 15 to 50 µm. Additionally, the peak-to-peak difference between the 2 waveforms ranged from 1 to 18 µm. Conclusion: Using a tissue phantom undergoing cyclical motion, we demonstrated the percent accuracy of DENSE MRI to measure displacement similar to that observed for in vivo cardiac-induced brain tissue.

Reproducibility of global and segmental myocardial strain using cine DENSE at 3 T: a multicenter cardiovascular magnetic resonance study in healthy subjects and patients with heart disease

“…The present results contribute to a thorough sequence of studies validating DENSE for the measurement of displacement and strain. Spottiswoode et al validated DENSE measurements of displacement in a rotating phantom for displacement values on the order of 2–20 mm [ 28 ], and Nwotchouang et al recently validated DENSE measurements of displacement in a phantom designed for much smaller displacements, on the order of 20–200um [ 37 ]. Cowan et al carefully validated DENSE measurements of strain using a deformable phantom, showing accuracy of strain that was similar to conventional tagging.…”

Cerebrospinal Fluid Flow and Brain Motion in Chiari I Malformation: Past, Present, and Future

“…This may be attributable to the ability of DENSE to directly measure displacement as well as differences in sample size of the studies 61,74 . Accuracy of the DENSE displacement measurements was confirmed using a phantom study 60 . In addition to evaluating displacement, assessment of strain (a measure of tissue deformation) exerted on these structures has further characterized the biomechanical environment in CMI 60,74 .…”

“…During each cine frame readout, the pixel-by-pixel displacement since the tagging module is displayed in the phase images. [60][61][62] Many of the subsequent studies used axial cine-PCMR. 7,9,12,66,67 Given that the axial plane is perpendicular to the axis of CSF flow, axial cine-PCMR is much better than sagittal cine-PCMR in assessing velocities and also can assess flow rate by combining flow area and average velocity over the cross-sectional area of flow/thecal sac.…”

In Vitro Validation of Regional Circumferential Strain Assessment in a Phantom Aortic Model Using Cine Displacement Encoding With Stimulated Echoes MRI

“…7 Following the success of cardiac DENSE MRI, other applications of DENSE to quantify regional biomechanical tissue behavior have been emerging. 8,9 One of the first attempts to apply DENSE to the aorta was by Haraldsson et al 10 Using 1.5 T MRI, they reported heterogeneous stretch around the ascending aorta when divided by quadrants; however, they did not report quantified patterns in regional strain distribution nor attempt to validate the technique. In 2018, Wilson et al outlined an improved DENSE technique using 3 T field strength and multiple noise-reducing post-processing algorithms to quantify patient-specific heterogeneous distributions of circumferential strain around the aortic wall at three locations along the aorta.…”

“…Following the success of cardiac DENSE MRI, other applications of DENSE to quantify regional biomechanical tissue behavior have been emerging 8,9 . One of the first attempts to apply DENSE to the aorta was by Haraldsson et al 10 Using 1.5 T MRI, they reported heterogeneous stretch around the ascending aorta when divided by quadrants; however, they did not report quantified patterns in regional strain distribution nor attempt to validate the technique.…”