Diffusion Tensor Magnetic Resonance Imaging‐Derived Myocardial Fiber Disarray in Hypertensive Left Ventricular Hypertrophy: Visualization, Quantification and the Effect on Mechanical Function

Giannakidis, Archontis; Rohmer, Damien; Veress, Alexander I.; Gullberg, Grant T.

doi:10.1002/9781118481585.ch53

Cited by 12 publications

(18 citation statements)

References 86 publications

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“…) and more recently to quantify myocardial disarray in hypertensive rat hearts by DT‐MRI (Giannakidis et al. ), where it was superior to fractional anisotropy as it provided more explicit information about irregularity. A key novelty of our work is the application of MDI to HREM enabling us to study the fetal and neonatal heart.…”

Section: Discussionmentioning

confidence: 99%

“…; Giannakidis et al. ). This index, which is equivalent to the intervoxel coherence index described by Giannakidis et al.…”

Section: Methodsmentioning

confidence: 98%

“…This index, which is equivalent to the intervoxel coherence index described by Giannakidis et al. (), quantifies, for each image voxel, the uniformity of the myocyte longitudinal direction (represented by the tertiary eigenvector v 3 , Fig. b) within a neighbourhood that consists of the voxel itself and its nearest neighbours.…”

Section: Methodsmentioning

confidence: 99%

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Myoarchitectural disarray of hypertrophic cardiomyopathy begins pre‐birth

et al. 2019

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Myoarchitectural disarray – the multiscalar disorganisation of myocytes, is a recognised histopathological hallmark of adult human hypertrophic cardiomyopathy (HCM). It occurs before the establishment of left ventricular hypertrophy (LVH) but its early origins and evolution around the time of birth are unknown. Our aim is to investigate whether myoarchitectural abnormalities in HCM are present in the fetal heart. We used wild‐type, heterozygous and homozygous hearts (n = 56) from a Mybpc3‐targeted knock‐out HCM mouse model and imaged the 3D micro‐structure by high‐resolution episcopic microscopy. We developed a novel structure tensor approach to extract, display and quantify myocyte orientation and its local angular uniformity by helical angle, angle of intrusion and myoarchitectural disarray index, respectively, immediately before and after birth. In wild‐type, we demonstrate uniformity of orientation of cardiomyocytes with smooth transitions of helical angle transmurally both before and after birth but with traces of disarray at the septal insertion points of the right ventricle. In comparison, heterozygous mice free of LVH, and homozygous mice showed not only loss of the normal linear helical angulation transmural profiles observed in wild‐type but also fewer circumferentially arranged myocytes at birth. Heterozygous and homozygous showed more disarray with a wider distribution than in wild‐type before birth. In heterozygous mice, disarray was seen in the anterior, septal and inferior walls irrespective of stage, whereas in homozygous mice it extended to the whole LV circumference including the lateral wall. In conclusion, myoarchitectural disarray is detectable in the fetal heart of an HCM mouse model before the development of LVH.

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Section: Discussionmentioning

confidence: 99%

“…; Giannakidis et al. ). This index, which is equivalent to the intervoxel coherence index described by Giannakidis et al.…”

Section: Methodsmentioning

confidence: 98%

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Myoarchitectural disarray of hypertrophic cardiomyopathy begins pre‐birth

et al. 2019

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“…To this end, we sought to ascertain in a quantitative manner the metric that achieved the greatest rectification of background noise-induced misaligned principal diffusion eigenvectors. Primary orientation is a piece of central information carried by the diffusion tensor data, as well as a main measure affected by disease (Giannakidis et al, 2012). The comparison performed in this paper showed that the linear and non-linear DT-MRI functions tend to provide equivalent results (Fig.…”

Section: Discussionmentioning

confidence: 99%

“…To this end, we relied on the intervoxel diffusion coherence (IVDC) index (Wang et al, 2008). The validity of the specific eigenvector homogeneity criterion for assessing the perturbation of cardiac tissue directional regularity due to disease has been tested elsewhere (Giannakidis et al, 2012). (ii) There exist few studies (Frindel et al, 2009; Yang et al, 2012; Collard et al, 2014; Zhou et al, 2015) that used fractional anisotropy (FA) to compare the various diffusion tensor distance functions.…”

Section: Introductionmentioning

confidence: 99%

On the averaging of cardiac diffusion tensor MRI data: the effect of distance function selection

Giannakidis¹,

Melkus²,

Yang³

et al. 2016

Phys. Med. Biol.

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Diffusion tensor magnetic resonance imaging (DT-MRI) allows a unique insight into the microstructure of highly-directional tissues. The selection of the most proper distance function for the space of diffusion tensors is crucial in enhancing the clinical application of this imaging modality. Both linear and nonlinear metrics have been proposed in the literature over the years. The debate on the most appropriate DT-MRI distance function is still ongoing. In this paper, we presented a framework to compare the Euclidean, affine-invariant Riemannian and log-Euclidean metrics using actual high-resolution DT-MRI rat heart data. We employed temporal averaging at the diffusion tensor level of three consecutive and identically-acquired DT-MRI datasets from each of five rat hearts as a means to rectify the background noise-induced loss of myocyte directional regularity. This procedure is applied here for the first time in the context of tensor distance function selection. When compared with previous studies that used a different concrete application to juxtapose the various DT-MRI distance functions, this work is unique in that it combined the following: (i) Metrics were judged by quantitative –rather than qualitative– criteria, (ii) the comparison tools were non-biased, (iii) a longitudinal comparison operation was used on a same-voxel basis. The statistical analyses of the comparison showed that the three DT-MRI distance functions tend to provide equivalent results. Hence, we came to the conclusion that the tensor manifold for cardiac DT-MRI studies is a curved space of almost zero curvature. The signal to noise ratio dependence of the operations was investigated through simulations. Finally, the “swelling effect” occurrence following Euclidean averaging was found to be too unimportant to be worth consideration.

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Value of Formalin Fixation for the Prolonged Preservation of Rodent Myocardial Microanatomical Organization: Evidence by MR Diffusion Tensor Imaging

Giannakidis

Gullberg

Pennell

et al. 2016

The Anatomical Record

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Previous ex vivo diffusion tensor imaging (DTI) studies on formalin fixed myocardial tissue assumed that, after some initial changes in the first 48 hours since the start of fixation, DTI parameters remain stable over time. Prolonged preservation of cardiac tissue in formalin prior to imaging has been seen many times in the DTI literature as it is considered orderly. Our objective is to define the effects of the prolonged cardiac tissue exposure to formalin on tissue microanatomical organization, as this is assessed by DTI parameters. DTI experiments were conducted on eight excised rodent hearts that were fixed by immersion in formalin. The samples were randomly divided into two equinumerous groups corresponding to shorter (~2 weeks) and more prolonged (~ 6–8 weeks) durations of tissue exposure to formalin prior to imaging. We found that when the duration of cardiac tissue exposure to formalin before imaging increased, water diffusion became less restricted, helix angle (HA) histograms flattened out and exhibited heavier tails (even though the classic HA transmural variation was preserved), and a significant loss of inter-voxel primary diffusion orientation integrity was introduced. The prolonged preservation of cardiac tissue in formalin profoundly affected its microstructural organization, as this was assessed by DTI parameters. The accurate interpretation of diffusivity profiles necessitates awareness of the pitfalls of prolonged cardiac tissue exposure duration to formalin. The acquired knowledge works to the advantage of a proper experimental design of DTI studies of fixed hearts.

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Diffusion Tensor Magnetic Resonance Imaging‐Derived Myocardial Fiber Disarray in Hypertensive Left Ventricular Hypertrophy: Visualization, Quantification and the Effect on Mechanical Function

Cited by 12 publications

References 86 publications

Myoarchitectural disarray of hypertrophic cardiomyopathy begins pre‐birth

Myoarchitectural disarray of hypertrophic cardiomyopathy begins pre‐birth

On the averaging of cardiac diffusion tensor MRI data: the effect of distance function selection

Value of Formalin Fixation for the Prolonged Preservation of Rodent Myocardial Microanatomical Organization: Evidence by MR Diffusion Tensor Imaging

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