HOMOR: Higher Order Model Outlier Rejection for high b-value MR diffusion data

Pannek, Kerstin; Raffelt, David; Bell, Christopher J.; Mathias, Jane L.; Rose, Stephen

doi:10.1016/j.neuroimage.2012.07.022

Cited by 45 publications

(42 citation statements)

References 24 publications

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“…171 This involves between-volume registration to account for head movement during the scan time using a fit model to all measurements (FMAM) method, 172 including adjustment of the b-matrix. 173, 174 DROP-R was modified from the originally proposed method to employ a model for the detection and replacement of outliers termed higher order model outlier rejection (HOMOR 175 ). FA and MD maps were then generated using the MRtrix package.…”

Section: Diffusion Processingmentioning

confidence: 99%

“…189 Motion artefacts were identified and replaced using Detection and Replacement of Outliers Prior to Resampling (DROP-R), 171 modified from the originally proposed method to incorporate an outlier detection technique suitable for high b-value diffusion data. 175 Using the corrected data, the fibre orientation distribution (FOD) was estimated using the constrained spherical deconvolution (CSD) method within the MRtrix package (https://github.com/jdtournier/mrtrix3).…”

Section: Diffusion Processingmentioning

confidence: 99%

“…Head movement within diffusion-weighted image volumes were identified using the discontinuity index 168 and movement between volumes was corrected using the Fit Model to All Measurements 175 was used to identify and replace motion artefacts. The fibre orientation distribution (FOD) was estimated in the corrected diffusion data using the constrained spherical deconvolution (CSD) method within the MRtrix package (https://github.com/jdtournier/mrtrix3).…”

Section: Diffusion Processingmentioning

confidence: 99%

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Investigating neural connectivity of corticomotor networks in ataxia telangiectasia: improving our understanding of the clinical phenotype

Sahama¹

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The human genetic disorder ataxia-telangiectasia (A-T) is an autosomal recessive neurodegenerative condition occurring in 3 per million live births. The disease is characterised by neurodegeneration, immunodeficiency, radiosensitivity, cell cycle checkpoint defects, genomic instability and cancer predisposition among patients. The most debilitating aspect of the disease is progressive cerebellar ataxia, which represents the hallmark neuropathological condition of A-T.At present, long term therapy to cure or prevent progressive symptoms of A-T are not currently available. While short term treatment to alleviate symptoms associated with immunodeficiency and deficient lung function are available to patients, the predisposition to cancer and the progressive neurodegeneration associated with A-T cannot be prevented with such efforts. To gain a more informed understanding of the A-T condition, research has focused on clinical, genetic and immunological aspects of the disorder; however, minimal attention has been directed towards identifying altered brain structure and function using imaging modalities such as magnetic resonance imaging (MRI).Imaging studies in A-T are limited to structural MRI imaging, where various radiological anomalies in patients are reported as clinical case studies. While these studies provide a detailed focus on the morphological and histopathological conditions of A-T, they provide limited insight into the mechanisms of neurodegeneration and loss of neural motor network connectivity among patients. In other ataxic diseases such as Friedrich's ataxia and spinocerebellar ataxia, the use of high-resolution MRI and diffusion-weighted imaging (DWI) has given valuable insight into the microstructural tissue environment, and the loss of white matter integrity of motor networks due to abnormal neurodevelopmental and/or progressive neurodegenerative conditions associated with the disease.Such imaging approaches have not yet been extended to the study of A-T, and could provide important new information regarding the relationship between the ataxia-telangiectasia gene mutation (ATM) and loss of motor pathway integrity in A-T patients. ivThe key objective of this PhD programme was to investigate white matter integrity and grey matter volume changes associated with A-T using a combination of structural MRI and diffusion-weighted imaging, to pinpoint potential neurodegenerative biomarkers that can be targeted for therapeutic use among young A-T patients. Performing diffusion imaging in children with A-T presents a significant challenge, as spontaneous movement at resting positions form part of the A-T condition, and nonsedated imaging procedures will contribute to excessive motion artefact and limited image quality in diffusion-weighted images. To effectively detect and correct for motion artefacts, a series of data preprocessing and correction steps were introduced to the DWI processing pipeline of A-T images in this project. Whole brain imaging analysis, specifically voxel-based morphometry (based...

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Section: Diffusion Processingmentioning

confidence: 99%

Section: Diffusion Processingmentioning

confidence: 99%

Section: Diffusion Processingmentioning

confidence: 99%

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Investigating neural connectivity of corticomotor networks in ataxia telangiectasia: improving our understanding of the clinical phenotype

Sahama¹

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“…This includes between-volume registration to account for head movement during the scan time using FMAM 121 including adjustment of the b-matrix 122,123 . DROP-R was modified from the originally proposed method to employ a higher order model for the detection and replacement of outliers suitable for high b-value diffusion data (HOMOR, 124 ) rather than the tensor model (RESTORE, 125 ).…”

Section: Diffusion Preprocessingmentioning

confidence: 99%

Motor, sensory and executive function brain networks in children with unilateral cerebral palsy

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“…Therefore, to perform DTI analysis, extensive pre-processing (Pannek, Raffelt et al 2012) is required to deal with these issues. higher values (closer to 1) represents anisotropic diffusion.…”

mentioning

confidence: 99%

Measuring the progression of upper motor neuron disease using diffusion MRI and its correlation with Clinical phenotype

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HOMOR: Higher Order Model Outlier Rejection for high b-value MR diffusion data

Cited by 45 publications

References 24 publications

Investigating neural connectivity of corticomotor networks in ataxia telangiectasia: improving our understanding of the clinical phenotype

Investigating neural connectivity of corticomotor networks in ataxia telangiectasia: improving our understanding of the clinical phenotype

Motor, sensory and executive function brain networks in children with unilateral cerebral palsy

Measuring the progression of upper motor neuron disease using diffusion MRI and its correlation with Clinical phenotype

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