Mapping immune cell infiltration using restricted diffusion <scp>MRI</scp>

Yeh, Fang‐Cheng; Liu, Li; Hitchens, T. Kevin; Wu, Yijen

doi:10.1002/mrm.26143

Cited by 129 publications

(102 citation statements)

References 43 publications

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“…Three dimensional probability information on the diffusion displacement was calculated in each voxel in the brain scans and then formed the spin distribution function. Micro-scale diffusivity was modeled for partial diffusion encoding length based on the weighted sum of partial spin distributions below upper bound of the diffusion displacement (Yeh et al, 2016). In this study, we applied 2 μm, 10 μm and 20 μm upper bounds for calculating the micro-scale diffusivity maps.…”

Section: Methodsmentioning

confidence: 99%

Corticosterone potentiates DFP-induced neuroinflammation and affects high-order diffusion imaging in a rat model of Gulf War Illness

Koo

Michalovicz

Calderazzo

et al. 2018

Brain, Behavior, and Immunity

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Veterans of the 1991 Gulf War were potentially exposed to a variety of toxic chemicals, including sarin nerve agent and pesticides, which have been suspected to be involved in the development of Gulf War Illness (GWI). Several of these exposures cause a neuroinflammatory response in mice, which may serve as a basis for the sickness behavior-like symptoms seen in veterans with GWI. Furthermore, conditions mimicking the physiological stress experienced during the war can exacerbate this effect. While neuroinflammation has been observed post-exposure using animal models, it remains a challenge to evaluate neuroinflammation and its associated cellular and molecular changes in vivo in veterans with GWI. Here, we evaluated neuroimmune-associated alterations in intact brains, applying our existing GWI mouse model to rats, by exposing them to 4days of corticosterone (CORT; 200mg/L in the drinking water), to mimic high physiological stress, followed by a single injection of the sarin nerve agent surrogate, diisopropyl fluorophosphate (DFP; 1.5mg/kg, i.p.). Then, we evaluated the neuroinflammatory responses using qPCR of cytokine mRNA and also examined brain structure with a novel high-order diffusion MRI. We found a CORT-enhancement of DFP-induced neuroinflammation, extending our mouse GWI model to the rat. High order diffusion MRI revealed different patterns among the different treatment groups. Particularly, while the CORT+DFP rats had more restricted spatial patterns in the hippocampus and the hypothalamus, the highest and most wide-spread differences were shown in DFP-treated rats compared to the controls in the thalamus, the amygdala, the piriform cortex and the ventral tegmental area. The association of these diffusion changes with neuroinflammatory cytokine expression indicates the potential for GW-relevant exposures to result in connectivity changes in the brain. By transferring this high order diffusion MRI into in vivo imaging in veterans with GWI, we can achieve further insights on the trajectories of the neuroimmune response over time and its impacts on behavior and potential neurological damage.

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Section: Methodsmentioning

confidence: 99%

Corticosterone potentiates DFP-induced neuroinflammation and affects high-order diffusion imaging in a rat model of Gulf War Illness

Koo

Michalovicz

Calderazzo

et al. 2018

Brain, Behavior, and Immunity

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“…15,16 The thermally driven mobility of water molecules as well as the flow of water molecules into randomly distributed capillaries and tubular structures result in an intra-voxel dephasing of the transverse magnetization, which contributes to the signal loss. [17][18][19] Besides providing measures of diffusion anisotropy and of the total degree of diffusion in the voxel, the sampling of the DWI signal within an optimal range of b-values and along at least six non-collinear diffusion-encoding directions within one single scan potentially allows tissue differentiation in terms of cellularity, [20][21][22] microstructure, 23,24 and perfusion. 25 The intrinsic T 2 weight of the low b-value volumes offers an additional tissue-specific element for classification.…”

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confidence: 99%

Automated pixel‐wise brain tissue segmentation of diffusion‐weighted images via machine learning

2018

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The diffusion-weighted (DW) MR signal sampled over a wide range of b-values potentially allows for tissue differentiation in terms of cellularity, microstructure, perfusion, and T relaxivity. This study aimed to implement a machine learning algorithm for automatic brain tissue segmentation from DW-MRI datasets, and to determine the optimal sub-set of features for accurate segmentation. DWI was performed at 3 T in eight healthy volunteers using 15 b-values and 20 diffusion-encoding directions. The pixel-wise signal attenuation, as well as the trace and fractional anisotropy (FA) of the diffusion tensor, were used as features to train a support vector machine classifier for gray matter, white matter, and cerebrospinal fluid classes. The datasets of two volunteers were used for validation. For each subject, tissue classification was also performed on 3D T -weighted data sets with a probabilistic framework. Confusion matrices were generated for quantitative assessment of image classification accuracy in comparison with the reference method. DWI-based tissue segmentation resulted in an accuracy of 82.1% on the validation dataset and of 82.2% on the training dataset, excluding relevant model over-fitting. A mean Dice coefficient (DSC) of 0.79 ± 0.08 was found. About 50% of the classification performance was attributable to five features (i.e. signal measured at b-values of 5/10/500/1200 s/mm and the FA). This reduced set of features led to almost identical performances for the validation (82.2%) and the training (81.4%) datasets (DSC = 0.79 ± 0.08). Machine learning techniques applied to DWI data allow for accurate brain tissue segmentation based on both morphological and functional information.

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“…The diffusion data were reconstructed using generalized q-sampling imaging [10] with a diffusion sampling length ratio of 1.25. The restricted diffusion was quantified using restricted diffusion imaging [11] to differentiate between tumor regions, edematous area, and normal white matter tissue. The tumor region and peritumoral edematous area were manually delineated to facilitate tracking the peritumoral fiber pathways.…”

Section: Tip Applied To Peritumoral Tractogrammentioning

confidence: 99%

Automatic Removal of False Connections in Diffusion MRI Tractography Using Topology-Informed Pruning (TIP)

et al. 2019

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Diffusion MRI fiber tracking provides a non-invasive method for mapping the trajectories of human brain connections, but its false connection problem has been a major challenge. This study introduces topology-informed pruning (TIP), a method that automatically identifies singular tracts and eliminates them to improve the tracking accuracy. The accuracy of the tractography with and without TIP was evaluated by a team of 6 neuroanatomists in a blinded setting to examine whether TIP could improve the accuracy. The results showed that TIP improved the tracking accuracy by 11.93% in the single-shell scheme and by 3.47% in the grid scheme. The improvement is significantly different from a random pruning (p value < 0.001). The diagnostic agreement between TIP and neuroanatomists was comparable to the agreement between neuroanatomists. The proposed TIP algorithm can be used to automatically clean-up noisy fibers in deterministic tractography, with a potential to confirm the existence of a fiber connection in basic neuroanatomical studies or clinical neurosurgical planning.

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Mapping immune cell infiltration using restricted diffusion MRI

Abstract: RDI can be used to reveal cell density and detect immune cell infiltration. RDI exhibits better specificity than the diffusivity measurement derived from DTI. Magn Reson Med 77:603-612, 2017. © 2016 International Society for Magnetic Resonance in Medicine.

Cited by 129 publications

References 43 publications

Corticosterone potentiates DFP-induced neuroinflammation and affects high-order diffusion imaging in a rat model of Gulf War Illness

Corticosterone potentiates DFP-induced neuroinflammation and affects high-order diffusion imaging in a rat model of Gulf War Illness

Automated pixel‐wise brain tissue segmentation of diffusion‐weighted images via machine learning

Automatic Removal of False Connections in Diffusion MRI Tractography Using Topology-Informed Pruning (TIP)

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