Amplified Flow Imaging (aFlow): A Novel MRI-Based Tool to Unravel the Coupled Dynamics Between the Human Brain and Cerebrovasculature

Abderezaei, Javid; Martinez, J. I.; Terem, Itamar; Fabris, Gloria; Pionteck, Aymeric; Yang, Yang; Holdsworth, Samantha J.; Nael, Kambiz; Kurt, Mehmet

doi:10.1109/tmi.2020.3012932

Cited by 19 publications

(25 citation statements)

References 87 publications

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“…Applying 3D aMRI to FLASH datasets revealed similar brain motion characteristics to that observed with bSSFP, with the additional advantage of being able to amplify major blood vessel motion which was shown to have a potential application in the assessment of evolving intracranial aneurysms. 34 It should be noted that the aMRI algorithm amplifies subtle intensity variations within each voxel regardless of the source that causes these changes. Some of these changes are induced by motion, and some of them can be due to noise and local B0 field gradients interacting with the motion.…”

Section: Discussionmentioning

confidence: 99%

“…By incorporating dynamic mode decomposition into the aMRI data processing pipeline, it has potential application in the assessment of evolving intracranial aneurysms. 34 In addition, by generating amplified strain maps, aMRI has also been shown to have relevance in studying the effects of head impacts on brain health, as a tool for tracking tissue strain. 35 In their study on subconcussive impacts, Champagne et al used aMRI together with diffusion tensor imaging and helmet accelerometer data to gather insight on the regionspecific vulnerability of the corpus callosum to microstructural changes in white-matter integrity.…”

Section: Introductionmentioning

confidence: 99%

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3D amplified MRI (aMRI)

Terem

Dang

Champagne

et al. 2021

Magnetic Resonance in Med

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Purpose Amplified MRI (aMRI) has been introduced as a new method of detecting and visualizing pulsatile brain motion in 2D. Here, we improve aMRI by introducing a novel 3D aMRI approach. Methods 3D aMRI was developed and tested for its ability to amplify sub‐voxel motion in all three directions. In addition, 3D aMRI was qualitatively compared to 2D aMRI on multi‐slice and 3D (volumetric) balanced steady‐state free precession cine data and phase contrast (PC‐MRI) acquired on healthy volunteers at 3T. Optical flow maps and 4D animations were produced from volumetric 3D aMRI data. Results 3D aMRI exhibits better image quality and fewer motion artifacts compared to 2D aMRI. The tissue motion was seen to match that of PC‐MRI, with the predominant brain tissue displacement occurring in the cranial‐caudal direction. Optical flow maps capture the brain tissue motion and display the physical change in shape of the ventricles by the relative movement of the surrounding tissues. The 4D animations show the complete brain tissue and cerebrospinal fluid (CSF) motion, helping to highlight the “piston‐like” motion of the ventricles. Conclusions Here, we introduce a novel 3D aMRI approach that enables one to visualize amplified cardiac‐ and CSF‐induced brain motion in striking detail. 3D aMRI captures brain motion with better image quality than 2D aMRI and supports a larger amplification factor. The optical flow maps and 4D animations of 3D aMRI may open up exciting applications for neurological diseases that affect the biomechanics of the brain and brain fluids.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

3D amplified MRI (aMRI)

Terem

Dang

Champagne

et al. 2021

Magnetic Resonance in Med

Self Cite

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“…We mimic the skull, which is orders of magnitudes stiffer than cerebral tissues, by prescribing zero-displacement boundary conditions on the outer periphery of our model. The brain deforms cyclically due to a combination of hemodynamic forces and CSF flow [64]. The lateral ventricles, in particular, undergo a piston-like motion causing cyclic volumetric expansion during systole [65].…”

Section: Ependymal Cell Stretch Along the Ventricular Wallmentioning

confidence: 99%

“…Here, we juxtapose our subject-specific model results with their structural and functional image data to test our proposed mechanism. Measuring in vivo wall motion via novel MRI techniques [64] and a histological study of the temporal decay of the ventricular wall would provide valuable data to further support and improve the accuracy of our model.…”

Section: Predictive Capabilities Of Our Modeling Approachmentioning

confidence: 99%

Onset location of periventricular white matter hyperintensities co-localizes with peak ependymal cell stretch

Visser

Rusinek

Weickenmeier

2021

Preprint

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Deep and periventricular white matter hyperintensities (dWMH/pvWMH) are bright appearing white matter tissue lesions in T2-weighted fluid attenuated inversion recovery magnetic resonance images and are frequent observations in the aging human brain. While early stages of these white matter lesions are only weakly associated with cognitive impairment, their progressive growth is a strong indicator for long-term functional decline. DWMHs are typically associated with diffuse vascular degeneration; for pvWMHs, however, no unifying theory exists to explain their characteristic onset locations and progression patterns. We use structural and functional patient imaging data to create anatomically accurate finite element models of the lateral ventricles, white and gray matter, and cerebrospinal fluid. We simulated the mechanical loading of the ependymal cells forming the primary brain-fluid interface, the ventricular wall, and its surrounding tissues at peak ventricular pressure during the hemodynamic cycle. We observe that both the maximum principal tissue strain and the largest ependymal cell stretch consistently localize in the anterior and posterior horns. Strikingly, these locations coincide with the pvWMHs observed in FLAIR images. We submit that the tight junctions between ependymal cells experience significant loads that cause the ventricular wall to be stretched thin and ultimately begin to leak. Besides age-related vascular degeneration, progressive wall failure causes neurotoxic fluid to diffuse into surrounding white matter structures and appear as growing pvWMHs. The physics-based approach presented here provides a novel model system to systematically study the progressive tissue deterioration associated with pvWMHs.

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“…The lack of in vivo data on the ventricular wall motion, however, is a major limitation to validating a dynamic simulation [47]. To further establish the role of mechanics in the onset and progression of pvWMHs, future work should look into the quantification of in vivo wall motion via novel MRI techniques [55] and a histological analysis of the ventricular wall's temporal decay.…”

Section: Mechanomarker For Periventricular White Matter Hyperintensitiesmentioning

confidence: 99%

Peak ependymal cell stretch overlaps with the onset location of periventricular white matter lesions

Visser

Rusinek

Weickenmeier

2021

Preprint

View full text Add to dashboard Cite

Deep and periventricular white matter hyperintensities (dWMH/pvWMH) are bright appearing white matter tissue lesions in T2-weighted fluid attenuated inversion recovery magnetic resonance images and are frequent observations in the aging human brain. While early stages of these white matter lesions are only weakly associated with cognitive impairment, their progressive growth is a strong indicator for long-term functional decline. DWMHs are typically associated with vascular degeneration in diffuse white matter locations; for pvWMHs, however, no unifying theory exists to explain their consistent onset around the horns of the lateral ventricles. We use patient imaging data to create anatomically accurate finite element models of the lateral ventricles, white and gray matter, and cerebrospinal fluid, as well as to reconstruct their WMH volumes. We simulated the mechanical loading of the ependymal cells forming the primary brain-fluid interface, the ventricular wall, and its surrounding tissues at peak ventricular pressure during the hemodynamic cycle. We observe that both the maximum principal tissue strain and the largest ependymal cell stretch consistently localize in the anterior and posterior horns. Our simulations show that ependymal cells experience a loading state that causes the ventricular wall to be stretched thin. Moreover, we show that maximum wall loading coincides with the pvWMH locations observed in our patient scans. These results warrant further analysis of white matter pathology in the periventricular zone that includes a mechanics-driven deterioration model for the ventricular wall.

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Amplified Flow Imaging (aFlow): A Novel MRI-Based Tool to Unravel the Coupled Dynamics Between the Human Brain and Cerebrovasculature

Cited by 19 publications

References 87 publications

3D amplified MRI (aMRI)

3D amplified MRI (aMRI)

Onset location of periventricular white matter hyperintensities co-localizes with peak ependymal cell stretch

Peak ependymal cell stretch overlaps with the onset location of periventricular white matter lesions

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