Anna Schroder¹, Neil P. Oxtoby¹, Marco Palombo¹, Simona Schiavi², Alessandro Daducci², and Daniel C. Alexander^1
1Centre for Medical Image Computing, Department of Computer Science, University College London, London, United Kingdom, ²Department of Computer Science, University of Verona, Verona, Italy

Network spreading models of disease propagation utilise functional or anatomical connectivity to predict regional pathology in-vivo. Models based on anatomical connectivity are likely to be disrupted by the inevitable presence of errors from tractography. To mitigate this problem, we propose a method to evaluate the potential of each tractography-derived connection to be false-positive. By incorporating this false-positive potential into a network spreading model, we are able to predict a pattern of tau accumulation more closely aligned with the pathology observed in a cohort of Alzheimer’s Disease patients.

Ryan McNaughton¹, Hernan Jara^1,2, Ning Hua^2,3, Andy Ellison^2,3, Osamu Sakai², Lee Goldstein^1,2,3, and Stephan Anderson^2,3
1Boston University, Boston, MA, United States, ²Boston University Medical Center, Boston, MA, United States, ³Center for Translational Neuroimaging, Boston, MA, United States

Purpose: To develop algorithms for mapping the spatial entropy (SE); extending white matter fibrography (WMF) for quantifying whole-brain information content. Methods: SE algorithms were applied to WM texture images of four individuals of increasing age, optimized for maximum information content, and implemented to calculate the whole-brain WM complexity. Results: SE was positively correlated with subject age. Conclusion: SE is a promising quantitative metric for objectively distinguishing the state of WM architecture from fibrograms, particularly as it relates to age effects.

Stephan Meesters^1,2, Maud Landers², Geert-Jan Rutten², and Luc Florack^1
1TU/e Eindhoven University of Technology, Eindhoven, Netherlands, ²ETZ Elisabeth-TweeSteden hospital, Tilburg, Netherlands

We have introduced an automatic pipeline based on diffusion-weighted tractography for the reconstruction of four white-matter structures of interest. These anatomical reconstructions are visualized during brain tumour surgery to aid in the prevention of sensorimotor, visual and language deficits. The automatic tractography pipeline produces robust results, owing in part to the deep-learning based segmentation of brain regions which is robust to deformations of the brain due to brain shift, and the post-tractography filtering method which can remove spurious fibers.

Umberto Villani^1,2, Erica Silvestri^1,2,3, Colpo Maria², D'Avella Domenico³, Della Puppa Alessandro⁴, Maurizio Corbetta^1,3, Cecchin Diego⁵, and Alessandra Bertoldo^1,2
1Padova Neuroscience Center, University of Padova, Padova, Italy, ²Department of Information Engineering, University of Padova, Padova, Italy, ³Department of Neuroscience, University of Padova, Padova, Italy, ⁴Department of Neurosurgery, University of Firenze, Firenze, Italy, ⁵Department of Medicine, Unit of Nuclear Medicine, University of Padova, Padova, Italy

We propose an application of the open-source whitematteranalysis software which moves a step towards the goal of reproducible and quantitative evaluation of anatomical tracts reconstruction by dMRI tractography. We quantify the tractogram in 11 patients suffering from brain tumours with four different algorithms, perform the automated spectral clustering procedure implemented in the software and evaluate simple metrics to compare the tractograms to an available anatomically curated atlas. Independently from the tumour position, the four investigated algorithms failed to properly reconstruct certain anatomical tracts. Evaluating the overall streamline representation of all tracts, the iFOD2 algorithm was found to perform best.

Maria Colpo¹, Erica Silvestri^1,2,3, Umberto Villani^1,2, Domenico D'Avella³, Alessandro Della Puppa⁴, Diego Cecchin^2,5, Maurizio Corbetta^2,3, and Alessandra Bertoldo^1,2
1Department of Information Engineering, University of Padova, Padova, Italy, ²Padova Neuroscience Center, University of Padova, Padova, Italy, ³Department of Neuroscience, University of Padova, Padova, Italy, ⁴Department of Neurosurgery, University of Firenze, Firenze, Italy, ⁵Department of Medicine, Unit of Nuclear Medicine, University of Padova, Padova, Italy

Varying termination criteria values of tractography algorithms produce tangible effects on the reconstructed tractograms. While these effects are extensively documented in the state-of-the-art literature for healthy subjects, little is known about streamline reconstruction differences in presence of brain tumours. In this work we apply a statistical framework to assess the impact of the cut-off value on the resulting structural connectivity matrices in 11 patients suffering from gliomas. Results show how varying the cut-off value in the studied range does not produce significant changes in the matrix structure, thus validating literature recommendations for healthy subjects in the case of glioma patients.

Bastian Maus^1,2, Lydia Wachsmuth^1,2, Maike Hoppen³, Jens Minnerup³, Antje Schmidt-Pogoda³, and Cornelius Faber^1,2
1Radiology, University Hospital Münster, Münster, Germany, ²Medical Faculty, Experimental Magnetic Resonance, Westfälische-Wilhelms-Universität Münster, Münster, Germany, ³Department of Neurology with Institute for Translational Neurology, University Hospital Münster, Münster, Germany

Ex vivo diffusion tensor imaging (DTI) was used to study the effects of motor training on interhemispheric connectivity after ischemic stroke in mice. Training increased the number of fibers of the corpus callosum by one third. No overall effect of lesion size on DTI parameters and general interhemispheric connectivity was observed. Trained animals with large lesions, however, had higher fiber counts and axial diffusivity compared to non-trained animals with similarly large lesions. A larger benefit of motor training on animals with more severe stroke is implied.

Ali Demir^1,2, Mehmed Özkan¹, and Aziz Müfit Uluğ^1,3
1Institute of Biomedical Engineering, Boğaziçi University, Istanbul, Turkey, ²Istanbul Medipol University, Istanbul, Turkey, ³Coretech Labs Inc., San Diego, CA, United States

Imaging based bio-markers are important in classification of psychiatric disorders for accurate diagnosis. We evaluated the performance of using a macroscopic dispersion measure of the white matter tractogram in the random forest classifier for identifying bipolar subjects. The macroscopic dispersion of the white matter tractogram enables increased performance of the bipolar/normal classification. Multidimensional scaling plots support that the macroscopic changes along the brain white matter improves the discrimination of bipolar and normal groups. 

Sang Jin Im¹, Jeong hwan Lee², and Sie kyeong Kim^3
1Gacheon University, Incheon, Korea, Republic of, ²2Department of Psychiatry, Chungbuk National University College of Medicine, Cheongju, Korea, Republic of, ³Department of Psychiatry, Chungbuk National University College of Medicine, Cheongju, Korea, Republic of

Structural and functional changes in the subcortical area affect cognitive function and can cause increased vulnerability to mood symptoms such as anxiety and depression.  However, studies on changes in subcortical structures show inconsistencies. This research shows the structural differences in segmented subcortical regions between control and depression groups and visualizes the pathway between structures according to the connection strength through tractography analysis to confirm functional differences. 

Nyoman Dana Kurniawan¹, Jin Jin², Clare Berry³, Wei Liu⁴, Aiman Al-Najjar¹, Katie L McMahon⁵, Tom Lloyd⁶, Silvia Manzanero⁷, James Powell⁸, Michael Schuetz⁷, Trevor Gervais⁹, and Paul McEniery^9
1Centre for Advanced Imaging, The University of Queensland, St Lucia, Australia, ²Siemens Healthcare, Brisbane, Australia, Brisbane, Australia, ³Metro North Hospital and Health Service, Brisbane, Australia, ⁴Application Department, Siemens Shenzhen Magnetic Resonance Ltd, Shenzhen, China, ⁵School of Clinical Sciences, Queensland University of Technology, Brisbane, Australia, ⁶Department of Radiology, Princess Alexandra Hospital, Brisbane, Australia, ⁷Jamieson Trauma Institute, Metro North Hospital and Health Service, Brisbane, Australia, ⁸Orthopaedics Department, Royal Brisbane and Women’s Hospital, Brisbane, Australia, ⁹Orthopedics Department, Royal Brisbane and Women’s Hospital, Brisbane, Australia

We describe the utility, optimization of a diffusion weighted imaging protocol, and the post-processing for fibertracking reconstruction of the brachial plexus nerve at 3T using a prototype Simultaneous Multi-Slice RESOLVE Diffusion-Weighted Imaging (SMS RESOLVE DWI) sequence. Best tractography profile was obtained for the acquisition acquired at 2.7 mm isotropic 3D resolution, using 7 segmentations, and 30 diffusion encoding directions at b-value of 800 s/mm², combined with tractography reconstruction using a probabilistic tensor algorithm.

Ryckie George Wade¹, Irvin Teh¹, Gustav Andersson², Fang-Cheng Yeh³, Mikael Wiberg², and Grainne Bourke^1
1University of Leeds, Leeds, United Kingdom, ²Umeå University, Umeå, Sweden, ³University of Pittsburgh, Pittsburgh, PA, United States

We acquired high-angular resolution DTI from 10 healthy adults. We investigated how altering the fractional anisotropy threshold changed tractograms and tract-related metrics. At thresholds above 0.06, the propagation of valid tracts reduced significantly. The fractional anisotropy thresholds required to generate valid tractograms of the roots of the brachial plexus are lower than thresholds conventionally used in the brain. We provide estimates of the probability of generating valid tracts for each spinal nerve root of the brachial plexus, at different fractional anisotropy thresholds.

Sheng-Min Huang¹, Kuan-Hung Cho¹, Koping Chang², Pei-Hsin Huang^2,3, and Li-Wei Kuo^1,4
1Institute of Biomedical Engineering and Nanomedicine, National Health Research Institutes, Miaoli, Taiwan, ²Department of Pathology, National Taiwan University Hospital, Taipei, Taiwan, ³Graduate Institute of Pathology, National Taiwan University College of Medicine, Taipei, Taiwan, ⁴Institute of Medical Device and Imaging, National Taiwan University College of Medicine, Taipei, Taiwan

Proper fiber connections between cerebral areas are particularly essential to build brain functions. As a central relay, the thalamus plays an important role in regulating diverse brain functions. Here, we aimed to investigate the thalamo-cortical connections and thalamic parcellation of ex vivo fetal brains in the second trimester using high-resolution postmortem diffusion MRI tractography on 3T. Diffusion images with 333 µm isotropic voxel size were acquired and tractography-based thalamic parcellation was performed. The segregated thalamic patterns were found as similar as adult’s ones reported previously. Our results showed the thalamic development and demonstrated the capability of postmortem diffusion MRI tractography. 

Sang Jin Im¹ and Hyeon-Man Baek^2
1Gacheon University, Incheon, Korea, Republic of, ²Lee Gil Ya Cancer and Diabetes Institute, Incheon, Korea, Republic of

Although there are discrepancies between studies, it can be deduced that the thalamus region has a clear effect on neurological disorders due to a strong relationship between the thalamus and neurological functions such as emotional control and processing. In this study, MPRAGE and DTI data were acquired using 3Tesla MRI, and thalamus regions were segmented by subdivisions based on the THOMAS atlas 4. In addition, tractography analysis was performed to investigate the connectivity between the thalamus subregions.

Rakshit Dadarwal^1,2, Fabien Balezeau³, Marcus Haag⁴, Michael C. Schmid^3,4, Susann Boretius^1,2, and Michael Oritz-Rios^1,3
1Functional Imaging Laboratory, German Primate Center, Göttingen, Germany, ²Georg August Universität Göttingen, Göttingen, Germany, ³Biosciences Institute, Newcastle University, Newcastle upon Tyne, United Kingdom, ⁴Faculty of Science and Medicine, University of Fribourg, Fribourg, Switzerland

In-vivo whole-brain multi-contrast awake imaging enables the detection of structural and functional features in brain networks without anesthesia. In this work, we demonstrated the feasibility and robustness of multi-contrast MRI data acquisitions across sessions and subjects in awake macaque monkeys. 

Fulvia Palesi^1,2, Matteo Ferrante³, Marta Gaviraghi⁴, Anastasia Misiti⁴, Giovanni Savini⁵, Alessandro Lascialfari³, Egidio D'Angelo^1,2, and Claudia A. M. Gandini Wheeler-Kingshott^1,2,6
1Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy, ²Brain Connectivity Center Research Department, IRCCS Mondino Foundation, Pavia, Italy, ³Department of Physics, University of Pavia, Pavia, Italy, ⁴Department of Electrical, Computer and Biomedical Engineering, University of Pavia, Pavia, Italy, ⁵Advanced Imaging and Radiomics Center, Neuroradiology Department, IRCCS Mondino Foundation, Pavia, Italy, ⁶NMR Research Unit, Queen Square MS Centre, Department of Neuroinflammation, UCL Queen Square Institute of Neurology, Faculty of Brain Sciences, University College London (UCL), London, United Kingdom

The dentate nuclei (DNs) represent the main output relay of the cerebellum and yet are often unexplored especially in human studies. For the first time, we used both tractography and an unsupervised fuzzy c-means classification algorithm to identify DNs topography on the basis of their connectivity to cerebellar and cerebral areas as well as their microstructural features. Our findings indicate that DNs can be parcellated in two main areas: one predominant non-motor representation and one motor representation. Furthermore, connectivity-based and microstructure-based atlases provide complementary information. These results represent a step-forward that could help interpretating pathological conditions involving cerebro-cerebellar circuits.

Olivier Commowick¹, Renaud Hédouin¹, Charlotte Laurent², and Jean-Christophe Ferré^1,3
1Univ Rennes, Inria, CNRS, Inserm, IRISA UMR 6074, Empenn - ERL U1228, Rennes, France, ²Ophthalmology department, CHU Rennes, Rennes, France, ³Radiology department, CHU Rennes, Rennes, France

Multiple sclerosis is a complex disease where voxel-based, group-based statistics of the brain microstructure have shown their limits in explaining patient evolution. This is first due to too simple diffusion models, mixing information. Voxel-based studies also lack knowledge on brain structural connectivity. Finally, group-based analysis does not describe well the specific patient status (a crucial point for clinicians). We propose an atlas-based framework, combined with advanced diffusion compartment models, for patient specific analysis of microstructural disease burden on major fiber bundles. We apply our framework to the analysis of optic radiations of MS patients with acute optic neuritis.

Jianzhong He^1,2, Fan Zhang², Guoqiang Xie^2,3, Shun Yao^2,4, Yuanjing Feng¹, Dhiego C.A. Bastos², Yogesh Rathi², Nikos Makris², Ron Kikinis², Alexandra J. Golby², and Lauren J. O'Donnell^2
1Zhejiang University of Technology, HangZhou, China, ²Harvard Medical School, Boston, MA, United States, ³Nuclear Industry 215 Hospital of Shaanxi Province, XianYang, China, ⁴The First Affiliated Hospital, GuangZhou, China

In this work, we investigate the performance of four widely used tractography methods (SD-Stream, iFOD1, UKF-1T, and UKF-2T) for the complete retinogeniculate visual pathway (RGVP) reconstruction. Anatomical measurement and expert judgement results indicate that UKF-2T and iFOD1 produce the best performance. The percentage of decussating fibers in the iFOD1 method was more similar to the known percentage from anatomical studies, while the UKF-2T method produced reconstructed RGVPs that were judged to better correspond to the anatomical course of the RGVP.

Yanming Wang¹, Xiaoxiao Wang¹, Hongmei Shi^2,3, Lin Xia², Jiong Dong², Benedictor Alexander Nguchu¹, Jean De Dieu Uwisengeyimana¹, Yanpeng Liu¹, Du Zhang¹, Lixia Feng², and Bensheng Qiu^1
1Hefei National Lab for Physical Sciences at the Microscale and the Centers for Biomedical Engineering, University of Science and Technology of China, Hefei, China, ²Department of Ophthalmology, The First Affiliated Hospital of Anhui Medical University, Hefei, China, ³Department of Ophthalmology, The People's Hospital of Bozhou, Bozhou, China

This study apply AFQ, in conjunction with MRtrix3 and ConTrack, to identify 24 major white matter fiber bundles in HCs, patients with XT before and after strabismus surgery. Meanwhile, we evaluate ocular dominance (OD) and stereo acuity of post-operative patients. We found that microstructures (MD) of vision-related fibers changed after surgery. Moreover, these changes were associated with indicators of OD. We infer that microstructural changes of the visual spatially related fiber bundles might contribute to the restoration of stereopsis, and the balanced binocular input may be more conducive to the improvements and restoration of binocular visual function.

Clement Jean¹, Arnaud Attyé^1,2, Alexandre Krainik¹, Sylvie Grand¹, Christophe Chiquet³, Olivier Casez⁴, Laurent Lamalle⁵, Felix Renard⁶, and Fernando Calamante^2,7
1Neuroradiology, Grenoble University Hospital, Grenoble, France, ²School of Biomedical Engineering, The University of Sydney, Sydney, Australia, ³Ophthalmology, Grenoble University Hospital, Grenoble, France, ⁴Neurology, Grenoble University Hospital, Grenoble, France, ⁵IRMaGe, Inserm US 17, CNRS UMS 3552, Grenoble, France, ⁶Pixyl Medical, Grenoble, France, ⁷Sydney Imaging, Sydney, Australia

TractLearn was recently proposed for tract-based MRI quantitative analyses, based on Riemannian distances between anatomical structures. It allows to detect joint quantitative variations in a group of voxels, and in theory to decrease the number of false negatives compared with the General Linear Model (GLM). TractLearn also takes advantage of a manifold approach to capture controls variability as standard reference. Here we aim at comparing the performance of TractLearn with the GLM in detecting optic nerve voxel alteration, using the side of visual impairment as clinical reference.

Sang-Jin Im¹ and Hyeon-Man Baek^1
1Lee Gil Ya Cancer and Diabetes Institute, Incheon, Korea, Republic of

Parkinson's disease is characterized by degeneration of dopaminergic nigrostriatal neurons with dysfunctional cortico–striatal–thalamic loops mainly in the basal ganglia. However, Parkinson’s disease studies on the neural connections between brain structural regions have not reached a clear consensus on how Parkinson’s disease effects the mouse brain. In this study, probabilistic tractography analysis was performed on important mouse brain structures related to Parkinson's disease mechanism, and pathways between each domain were visualized. 

Maud Landers¹, Stephan Meesters², Wouter de Baene³, and Geert-Jan Rutten^1
1Department of Neurosurgery, Elisabeth TweeSteden Hospital, Tilburg, Netherlands, ²Department of mathematics and Computer Science, University of Technology, Eindhoven, Netherlands, ³Department of Cognitive Neuropsychology, University of Tilburg, Tilburg, Netherlands

Currently there is insufficient knowledge about the right frontal aslant tract’s exact cognitive importance. The aim of this study was to investigate the role of the right frontal aslant tract in executive functions via a lesion-symptom approach. The results suggest that the right frontal aslant tract is involved in shifting attention and phonemic fluency. As a follow-up the main findings were tested and validated in an awake mapping study where stimulation of the right frontal aslant tract lead to deficits in executive functioning.