Yao-Chia Shih^1,2, Qi Rong Leon Ooi³, Septian Hartono^2,3, Thomas Welton^2,3, Hui-Hua Li^2,4, John Carson Allen², Eng King Tan^2,3, and Ling Ling Chan^1,2
1Department of Diagnostic Radiology, Singapore General Hospital, Singapore, Singapore, ²Duke-NUS Medical School, Singapore, Singapore, ³Department of Neurology, National Neuroscience Institute (Outram-campus), Singapore, Singapore, ⁴Health Services Research Unit, Singapore General Hospital, Singapore, Singapore

Diffusion tensor imaging (DTI) characterizes microstructural changes in the basal ganglia in relation to idiopathic Parkinson's disease (PD). However, inconsistent results due to short-interval longitudinal studies with heterogeneous neuropathology across PD stages have been reported. We elucidated microstructural changes in the deep gray nuclei throughout the disease course in a large, prospective, three time-point case-control DTI study in PD over twelve years, with six-year interval gaps. Increased mean striatal diffusivity reflected progressive neurodegeneration, whereas factional anisotropy changes suggested effects of abnormal iron accumulation followed by neuronal loss in the putamen and thalamus as the disease progresses into the late stages.

Yiming Xiao^1,2, Terry M Peters^3,4,5, and Ali R Khan^3,4,5,6
1PERFORM Centre, Concordia University, Montreal, QC, Canada, ²Computer Science and Software Engineering, Concordia University, Montreal, QC, Canada, ³Robarts Research Institute, Western University, London, ON, Canada, ⁴Department of Medical Biophysics, Western University, London, ON, Canada, ⁵School of Biomedical Engineering, Western University, London, ON, Canada, ⁶The Brain and Mind Institute, Western University, Lonon, ON, Canada

Understanding microstructural alterations in white matter can be instrumental in revealing pathogenesis and devising effective plans to treat Parkinson’s disease (PD). Diffusion MRI can be used to characterize the status of white matter integrity. With voxel-based analysis using DTI measures and fixel-based analysis (FBA), we demonstrated for the first time strengthened and weakened white matter integrity, which is subject to laterality of motor symptoms in de novo Parkinson’s disease. The findings suggest that the disease gives rise to both functional degeneration and the creation of compensatory networks.

Xueqin Bai¹, Tao Guo¹, Xiaojun Guan ¹, Cheng Zhou¹, Jingjing Wu¹, Xiaocao Liu¹, Ting Gao¹, Luyan Gu¹, Xiaojun Xu¹, Peiyu Huang¹, and Minming Zhang^1
1The second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China

In this study, we employed diffusion kurtosis imaging (DKI) and diffusion tensor imaging (DTI) to measure the microstructural alterations in subcortical nuclei across PD patients at different disease stages. Individual diagnostic model was constructed to test the performance of diffusion metrics in identifying PD patients at different stages.  We found that PD patients at different stages have progressive microstructural alterations in the main nuclei of widely acknowledged nigral-pallidal and thalamo-cortical pathways. DKI is sensitive to detect microstructural changes in GP and thalamus between early stage PD and moderate-late stage PD patients. The combination of kurtosis and tensor metrics can achieve a good performance in diagnosing PD.

Thomas Welton^1,2, Septian Hartono³, Yao-Chia Shih³, Samuel Y-E Ng¹, Nicole S Y Chia¹, Weiling Lee³, Say Lee Chong³, Eng-King Tan^1,2,3, Ling-Ling Chan^1,2,3, and Louis CS Tan^1,2
1National Neuroscience Institute, Singapore, Singapore, ²Duke-NUS Medical School, Singapore, Singapore, ³Singapore General Hospital, Singapore, Singapore

We show that the diffusion kurtosis characteristics of grey matter nuclei in early Parkinson's disease were abnormal and that this abnormality was maintained over two years. Furthermore, elevated mean kurtosis was associated with worsening motor function. This supports the use of diffusion kurtosis imaging to characterise tissue microstructure and potentially monitor disease progression even in early Parkinson's disease.

Yu Shen¹, Xianchang Zhang², Yan Bai¹, Rui Zhang¹, Rushi Chen¹, Wei Wei¹, Menghuan Zhang¹, and Meiyun Wang^1
1Department of Medical Imaging, Henan Provincial People’s Hospital & Zhengzhou University, Zhengzhou, China, ²MR Collaboration, Siemens Healthcare Ltd. Beijing China, Beijing, China

Magnetic resonance-guided focused ultrasound (MRgFUS) is a non-invasive tremor therapy associated with Parkinson disease (PD). Conventional fractional anisotropy analysis might neglect pre- and postoperative microanatomic changes due to low spatial resolution. Finer brain structural depictions could be provided using track density imaging (TDI), a super-resolution reconstruction method. This study conducted TDI on seven patients with PD before and 1-month after MRgFUS and found that tract density values were significantly decreased postoperatively in the genu of the corpus callosum and left globus pallidus. TDI could be a valuable tool for detecting microstructural changes after MRgFUS therapy.  

Emma Biondetti^1,2,3, Mathieu D. Santin^1,2, Romain Valabrègue^1,2, Graziella Mangone^1,4, Rahul Gaurav^1,2,3, Nadya Pyatigorskaya^1,3,5, Matthew Hutchison⁶, Lydia Yahia-Cherif^1,2, Nicolas Villain^1,7, Marie-Odile Habert⁸, Isabelle Arnulf^1,3,9, Smaranda Leu-Semenescu⁹, Pauline Dodet⁹, Jean-Christophe Corvol^1,4,7, Marie Vidailhet^1,3,7, and Stéphane Lehéricy^1,2,3,5
1Institut du Cerveau – ICM, INSERM U 1127, CNRS UMR 7225, Sorbonne Université, Paris, France, ²ICM, Centre de NeuroImagerie de Recherche – CENIR, Paris, France, ³ICM, Team “Movement Investigations and Therapeutics” (MOV’IT), Paris, France, ⁴National Institute of Health and Medical Research - INSERM, Clinical Investigation Centre, Pitié-Salpêtrière Hospital, Paris, France, ⁵Department of Neuroradiology, Pitié-Salpêtrière Hospital, AP-HP, Paris, France, ⁶Biogen Inc., Cambridge, MA, United States, ⁷Department of Neurology, Pitié-Salpêtrière Hospital, AP-HP, Paris, France, ⁸Department of Nuclear Medicine, Pitié-Salpêtrière Hospital, AP-HP, Paris, France, ⁹National Reference Center for Rare Hypersomnias, Pitié-Salpêtrière Hospital, AP-HP, Paris, France

Parkinson's disease (PD) and idiopathic rapid eye movement sleep behaviour disorder (iRBD, a prodromal condition of Parkinsonism) are characterised by progressive striatal dopaminergic denervation, loss of neuromelanin-containing neurons and increased iron deposition in the substantia nigra. Here, we evaluated neurodegeneration-induced changes in the nigrostriatal system of PD and iRBD patients using longitudinal SPECT and MR imaging compared to healthy control subjects. We showed that dopamine, neuromelanin and iron changes followed similar spatiotemporal gradients of neurodegeneration, and we assessed the temporal onset and ordering of such changes.

Yue Xing^1,2,3, Saadnah Naidu^1,2,3, Halim Abdul-Sapuan^1,2,3, Ali-Reza Mohammadi-Nejad^2,3, Jonathan Evans⁴, Ofer Pasternak⁵, Stamatios Sotiropoulos^2,3, Christopher R. Tench^1,3, and Dorothee P. Auer^1,2,3
1Division of Clinical Neuroscience, Queen’s Medical Centre, University of Nottingham, Nottingham, United Kingdom, ²Sir Peter Mansfield Imaging Centre, University of Nottingham, Nottingham, United Kingdom, ³NIHR Nottingham Biomedical Research Centre, University of Nottingham, Nottingham, United Kingdom, ⁴Department of Neurology, Nottingham University Hospital Trust, Nottingham, United Kingdom, ⁵Departments of Psychiatry and Radiology (O.P.), Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States

Parkinson’s Disease (PD) is characterized by loss of neuromelanin-containing dopaminergic neurons in the substantia nigra (SN), resulting in depigmentation as its pathological hallmark. Neuromelanin (NM)-sensitive-MRI consistently shows PD-related nigral signal-loss with limited evidence for longitudinal change. Nigral free-water (FW) derived from diffusion-MRI can track disease progression. This multimodal-serial study compared subregional annual depigmentation rates and FW in PD and controls. Longitudinal NM signal-loss and FW increase was seen in PD throughout the SN with significant acceleration compared to controls in the ventral-SN. There was no between-metrics correlation, suggesting that these promising serial biomarkers may track different aspects of PD progression.

Vicente Jose Ferrer-Gallardo¹, Thomas Bolton², Manuel Delgado³, Pedro M. Paz-Alonso¹, Maricuz Rodriguez-Oroz⁴, and César Caballero-Gaudes^1
1Basque Center on Cognition, Brain and Language, Donostia, Spain, ²Medical image processing, Swiss Federal Institute of Technology Lausanne, Lausanne, Switzerland, ³Department of Neurology, Sierrallana Hospital, Torrelavega, Spain, ⁴Neurology Department, Clinica Universidad de Navarra, Pamplona, Spain

Cognitive deficits in Parkinson’s Disease (PD) are associated with abnormalities in functional brain networks that can be observed at rest. This study investigates whole-brain independent functional-connectomes in PD patients with mild cognitive impairment (PD-MCI), associating these functional connectomes with cognitive and anthropometric measures using partial least squares (PLS) regression. We found a clear distinction between two sets (PLS-components) with functional connectomes either linked to cognitive scores or anthropometric variables. A PD-specific subcortical-cortical functional connectome was common in the two PLS-components. Furthermore, in PD-MCI a functional connectome defined by attentional and sensorimotor regions linked to attention and memory deficits is critical.

Jianli Wang¹, Rachel Stanford¹, Lauren Spreen², Jeffrey Vesek², Christopher Sica¹, Thyagarajan Subramanian³, and Qing X Yang^4
1Radiology, Penn State College of Medicine, HERSHEY, PA, United States, ²Molecular Biology, Penn State College of Medicine, HERSHEY, PA, United States, ³Neurology, Penn State College of Medicine, HERSHEY, PA, United States, ⁴Neurosurgery, Penn State College of Medicine, HERSHEY, PA, United States

Hyposmia is prevalent in Parkinson’s disease (PD) and the central olfactory system is highly affected by PD pathology. Despite the considerable progresses in understanding the pathophysiology of the disease, the mechanism causing hyposmia in PD is still unclear. Given that there is early PD-related neurodegeneration in anterior olfactory nucleus, which is a part of the primary olfactory cortex, we tested the hypothesis that there are PD-related dysfunctions in the central olfactory functional network at the early stage of disease.

Bhumi Bhusal¹, Jason Stockmann², Azma Mareyam², John Kirsch², Lawrence L Wald², Mark J Nolt¹, Joshua Rosenow¹, Roberto Lopez-Rosado¹, Behzad Elahi¹, and Laleh Golestanirad^1
1Northwestern University, Chicago, IL, United States, ²Massachusetts General Hospital, Charlestown, MA, United States

We report the results of MRI safety and image artifact assessment of a commercial deep brain stimulation (DBS) system implanted in an anthropomorphic phantom, undergoing MRI at 7T.  RF heating was observed to be less than 2°C for all clinically relevant as well as worst-case configurations evaluated in the study.  The magnetic force on the pulse generator was found to be within the safe limit. Metal-induced image artifact was comparable to what is observed at lower fields. Our results indicate that 7T MRI could be performed safely in patients with DBS implants under carefully evaluated device model and MRI hardware.