Myocardial infarct delineation in vivo using diffusion tensor MRI and the tractographic propagation angle

Mekkaoui, Choukri; Huang, Shuning; Dai, Guangping; Reese, Timothy G.; Ruskin, Jeremy N.; Hoffmann, Udo; Jackowski, Marcel P.; Sosnovik, David E.

doi:10.1186/1532-429x-15-s1-p2

Cited by 8 publications

(4 citation statements)

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“…Limited literature is available on TTA and its variation as a result of infarction. To the best of our knowledge, only one group has reported change in propagation angle (the average angle between adjacent eigenvectors along myofiber tracts) with MI [55, 56]. However, they have not mentioned any change in TTA with MI and therefore, we cannot directly compare our results to theirs.…”

Section: Discussionmentioning

confidence: 82%

Diffusion Tensor Imaging of Healthy and Infarcted Porcine Hearts: Study on the Impact of Formalin Fixation

Mazumder

Choi

Clymer

et al. 2016

Journal of Medical Imaging and Radiation Sciences

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Background Due to complexities of in-vivo cardiac diffusion tensor imaging (DTI), ex-vivo formalin-fixed specimens are used to investigate cardiac remodeling in diseases, and reported results have shown conflicting trends. This study investigates the impact of formalin-fixation on diffusion properties and optimizes tracking parameters based on controls to understand remodeling in myocardial-infarction (MI). Methods DTI was performed on 4 healthy (controls) and 4 MI induced formalin-fixed (PoMI) ex-vivo porcine hearts. Controls were scanned pre-fixation (PrCtrl) and re-scanned (PoCtrl) after formalin-fixation. Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) were estimated in all hearts. Tracking parameters (FA, tract termination angle (TTA), fiber-length) were optimized in controls and then used to investigate structural remodeling in PoMI hearts. Results Fixation increased ADC and decreased FA. PoMI showed increased ADC but decreased FA in infarcted zone compared to remote zone. TTA showed sharp increase in slope from 5°–10°, which flattened after 25° in all groups. Mean fiber-length for different tracking length range showed that PoCtrl had shorter fibers compared to PrCtrl. Fibers around infarction were shorter in length and disarrayed compared to PoCtrl group. Conclusion Formalin-fixation affects diffusion properties and hence DTI parametric trends observed in pathology may be influenced by the fixation process which can cause contradictory findings.

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Section: Discussionmentioning

confidence: 82%

Diffusion Tensor Imaging of Healthy and Infarcted Porcine Hearts: Study on the Impact of Formalin Fixation

Mazumder

Choi

Clymer

et al. 2016

Journal of Medical Imaging and Radiation Sciences

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“…Finally, a limitation was the relatively small number of animals (five swines); however, there were nine samples for which whole-mount histology and quantitative analysis were performed, and that proved to be sufficient for the statistical analysis. Experimental chronic infarct studies in animals are extremely difficult and costly to perform; other recent similar MR or MR-EP studies that included histology slides were reported in n = 6 rats (Schelbert et al 2010), n = 4 sheep (Mekkaoui et al 2011) and n = 5 swine (Nakahara et al 2011).…”

Section: Discussionmentioning

confidence: 99%

Quantification of fibrosis in infarcted swine hearts byex vivolate gadolinium-enhancement and diffusion-weighted MRI methods

et al. 2013

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Many have speculated that MRI signal characteristics can be used to identify regions of heterogeneous infarct associated with an arrhythmogenic substrate; however, direct evidence of this relationship is limited. The aim of this study was to demonstrate the remodelling characteristics of fibrosis by means of histology and high-resolution MR imaging. For this purpose, we performed whole-mount histology in heart samples (n = 9) collected from five swine at six weeks post-infarction and compared the extent of fibrosis in the infarcted areas delineated in these histological images with that obtained ex vivo by MRI using late gadolinium-enhancement (LGE) and diffusion-weighted imaging (DWI) methods. All MR images were obtained at a submillimetre resolution (i.e., voxel size of 0.6×0.6×1.2 mm(3)). Specifically, in the histology images, we differentiated moderate fibrosis (consisting of a mixture of viable and non-viable myocytes, known as border zone, BZ) from severe fibrosis (i.e., the dense scar). Correspondingly, tissue heterogeneities in the MR images were categorized by a Gaussian mixture model into healthy, BZ and scar. Our results showed that (a) both MRI methods were capable of qualitatively distinguishing sharp edges between dense scar and healthy tissue from regions of heterogeneous BZ; (b) the BZ and dense scar areas had intermediate-to-high increased values of signal intensity in the LGE images and of apparent diffusion coefficient in the DWI, respectively. In addition, as demonstrated by the Picrosirius Red and immunohistochemistry stains, the viable bundles in the BZ were clearly separated by thin collagen strands and had reduced expression of Cx43, whereas the core scar was composed of dense fibrosis. A quantitative analysis demonstrated that the comparison between BZ/scar extent in LGE and DWI to the corresponding areas identified in histology yielded very good correlations (i.e., for the scar identified by LGE, R(2) was 0.96 compared to R(2) = 0.93 for the scar identified in ADC maps, whereas the BZ had R(2) = 0.95 for the correlation between LGE and histology compared to R(2) = 0.91 obtained for ADC). This novel study represents an intermediate step in translating such research to the in vivo stages, as well as in establishing the best and most accurate MR method to help identify arrhythmia substrate in patients with structural heart disease.

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“…It estimates myocardial fiber orientations by measuring the diffusion displacement distribution of water molecules in fibrous tissue from diffusion weighted (DW) images along different diffusion gradient directions. Diffusion metrics, including fractional anisotropy (FA), mean diffusivity (MD) and helix angle (HA) are often calculated from DTI for describing the myocardium structure [6]- [8].…”

Section: Introductionmentioning

confidence: 99%

Investigation of in Vivo Human Cardiac Diffusion Tensor Imaging Using Unsupervised Dense Encoder-Fusion-Decoder Network

Deng

Wang

et al. 2020

IEEE Access

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Diffusion tensor imaging (DTI) is currently the unique imaging technique that can detect the structure of in-vivo human myocardium without invasivity and radiation. However, it is particularly sensitive to motions, especially respiratory motion that results in serious signal loss in diffusion-weighted (DW) images. This makes it impossible to accurately measure cardiac microscopic structural properties. To cope with such problem, this paper proposes an unsupervised dense-encoder-fusion-decoder network (DEFD-net) to compensate for signal loss in cardiac DW images, which allows investigating in-vivo myocardium structure more accurately. The DEFD-net consists of three modules, namely dense-encoder, fusion module and decoder module. The denseencoder and decoder are trained firstly with DW images acquired at different trigger delays in an unsupervised manner for extracting local and global features. A fusion strategy is then designed to fuse the extracted features. Finally, the well-trained decoder is used to reconstruct the fused DW image from the fused features. To validate the superiority of the proposed method, comparison with existing methods such as PCAMIP, WIF and U2Fusion is performed on both simulated and acquired datasets. The experimental results showed that the proposed method effectively compensates for motion-induced signal loss in DW images, thus leading to much better DW image quality with respect to existing methods. Moreover, the subsequently derived myocardium fiber structure is more regular.

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Myocardial infarct delineation in vivo using diffusion tensor MRI and the tractographic propagation angle

Cited by 8 publications

References 1 publication

Diffusion Tensor Imaging of Healthy and Infarcted Porcine Hearts: Study on the Impact of Formalin Fixation

Diffusion Tensor Imaging of Healthy and Infarcted Porcine Hearts: Study on the Impact of Formalin Fixation

Quantification of fibrosis in infarcted swine hearts byex vivolate gadolinium-enhancement and diffusion-weighted MRI methods

Investigation of in Vivo Human Cardiac Diffusion Tensor Imaging Using Unsupervised Dense Encoder-Fusion-Decoder Network

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