Elior Drori¹, Shai Berman¹, and Aviv Mezer^1
1The Edmond and Lily Safra Center for Brain Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel

The striatum is a heterogeneous brain structure with microstructural gradients along its main axes. Changes in its organization are associated with Parkinson’s disease (PD). Yet the spatial variability in the human striatum is not well characterized and is mostly limited to animal and postmortem studies. We developed a non-invasive MRI method for measurement of microstructural gradients along axes of the striatum in individuals in vivo. Using clinical data, we found a T1w/T2 gradient along the anterior-posterior axis of the putamen, which is decreased in PD. This decrease explains the patients’ asymmetries in dopamine loss and motor symptoms.

Chungseok Oh¹, Chang-Yeop Jeon², Jincheol Seo², Hyeong-Geol Shin¹, Sooyeon Ji¹, Seongbeom Park³, Soohwa Song³, Dong Hoon Shin³, Youngjeon Lee², and Jongho Lee^1
1Department of Electrical and Computer Engineering, Seoul National University, Seoul, Korea, Republic of, ²National Primate Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Cheongju, Korea, Republic of, ³Heuron Co.,Ltd, Incheon, Korea, Republic of

In this study, a hyperintensity region within substantia nigra is explored in cynomolgus monkeys over a wide range of ages. This region is similar to that of humans, which is often called as a swallow tail sign in healthy subjects. This nigral hyperintensity appears consistently in SMWI, QSM, and T₂*-weighted images, particularly in aged animals.

Rahul Gaurav^1,2, Romain Valabrègue², Nadya Pyatigorskaya^1,2,3, Graziella Mangone⁴, Smaranda Leu-Semenescu⁵, Jean-Christophe Corvol^4,6, Marie Vidailhet^1,6, Isabelle Arnulf^1,5, and Stephane Lehericy^1,2,3
1Movement Investigations and Therapeutics Team (MOV’IT), Paris Brain Institute (ICM), Paris, France, ²CENIR, Paris Brain Institute (ICM), Paris, France, ³Department of Neuroradiology, Pitié-Salpêtrière Hospital, AP-HP, Paris, France, ⁴INSERM, Clinical Investigation Center for Neurosciences (CIC), Paris Brain Institute (ICM), Paris, France, ⁵Sleep Disorders Unit, Pitié-Salpêtrière Hospital, AP-HP, Paris, France, ⁶Department of Neurology, Pitié-Salpêtrière Hospital, AP-HP, Paris, France

Isolated REM sleep behavior disorder (iRBD) is considered a prodromal stage of parkinsonism. Neurodegenerative changes in the substantia nigra pars compacta (SNc) in parkinsonism can be detected using neuromelanin-sensitive MRI. In this cross-sectional, observational, case-control study, we investigated changes in neuromelanin in participants with iRBD compared to Parkinson’s disease and healthy volunteers in the SNc segmented automatically using convolutional neural network-based U-net architecture. The iRBD participants had reduced neuromelanin content at an intermediate level between the values in HV and PD patients.

Sooyeon Ji¹, Eun-Jung Choi¹, Beomseok Sohn², Kyoungwon Baik², Eung Yeop Kim³, In Seong Kim⁴, Jin Wook Choi⁵, Seongbeom Park⁶, Soohwa Song⁶, Dong Hoon Shin⁶, Phil Hyu Lee⁷, and Jongho Lee^1
1Seoul National University, Seoul, Korea, Republic of, ²Severance Hospital, Seoul, Korea, Republic of, ³Department Radiology, Samsung Medical Center, Seoul, Korea, Republic of, ⁴Siemens Healthineers Ltd., Seoul, Korea, Republic of, ⁵Department of Radiology, Ajou University School of Medicine, Ajou University Medical Center, Suwon, Korea, Republic of, ⁶Heuron Co. Ltd., Incheon, Korea, Republic of, ⁷Department of Neurology, Severance Hospital, Seoul, Korea, Republic of

Multi-echo sandwich spatial saturation neuromelanin (sandwichNM_multi-echo) imaging is proposed to simultaneously acquire a high-quality neuromelanin-sensitive image, a co-localized T₂* map, and an improved susceptibility map weighted image for nigral hyperintensity. When this method is applied for PD patients and healthy controls, the results suggest that the reduced neuromelanin contrast in PD is partially explained by shorter T₂* in substantia nigra of the PD patients. Initial results at 7T further support the finding, suggesting a need for T₂* correction in assessing the NM-sensitive images.

YUE XING^1,2,3, Saadnah Naidu^1,2,3, Marta Gennaro^4,5, Andreas Antonios-Roussakis⁶, Nicholas P. Lao-Kaim⁴, Halim Abdul-Sapuan^1,2,3, Jonathan Evans⁷, Gillian Sare⁷, Antonio Martin-Bastida^4,8, Schwarz T. Stefan^1,2,9, Paola Piccini^4,6, and Dorothee P Auer^1,2,3
1Mental Health and Clinical Neuroscience Unit, 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, ⁴Division of Neurology, Imperial College London, London, United Kingdom, ⁵Nuclear Medicine department, Royal Brompton & Harefield hospitals, London, United Kingdom, ⁶NHLI Department, Imperial College London, London, United Kingdom, ⁷Nottingham University Hospitals, Nottingham, United Kingdom, ⁸Department of Neurology and Neurosciences, Clínica Universidad de Navarra, Pamplona-Madrid, Spain, ⁹Department of Radiology, Cardiff and Vale University Health Board, Cardiff, United Kingdom

Brain dopamine transporter (DAT) imaging with 123I-FP-CIT SPECT has been used for detecting striatal deficits in clinically uncertain parkinsonism (CUP). Neuromelanin(NM)-MRI assesses nigral depigmentation with high accuracy in confirmed PD; but its diagnostic value in CUP is unclear. Here, we compare nigral NM in CUP with (DAT+) or without (DAT-) striatal dopaminergic deficits, to established PD and healthy controls. CUP with DAT+ had more nigral NM deficits (vs. controls and DAT-CUP) but were less pronounced than in established PD. Interestingly, DAT- cases showed ventrolateral nigral deficits. Our results suggest that nigral depigmentation possibly starts before striatal dopaminergic decline.

Jason Langley¹, Kristy S. Hwang^2,3, Daniel E. Huddleston⁴, and Xiaoping Hu^1,5
1Center for Advanced Neuroimaging, University of California Riverside, Riverside, CA, United States, ²Department of Neurosciences, University of California San Diego, San Diego, CA, United States, ³Parkinson & Other Movement Disorders Center, University of California San Diego, San Diego, CA, United States, ⁴Department of Neurology, Emory University, Atlanta, GA, United States, ⁵Department of Bioengineering, University of California Riverside, Riverside, CA, United States

We examine nigral volume and tissue microstructure in prodromal and symptomatic Parkinson’s disease. Decreases in nigral volume were observed in the symptomatic Parkinson's disease group relative to the control group (p<10^-3) and prodromal Parkinson's disease (p<10^-3) group. A reduction in nigral volume was seen in the prodromal Parkinson's disease group relative to the control group (p=0.025). An increase in nigral free water was also found in the symptomatic Parkinson’s disease group relative to the control group (p=0.014).

Zhaoxi Liu¹, Yiwei Zhang², Han Wang¹, Dan Xu¹, Bo Wu³, E. Mark Haackeb⁴, Hui You¹, and Feng Feng^1
1Peking Union Medical College Hospital, Bejing, China, ²Peking university first hospital, Bejing, China, ³SpinTech, Inc., Bingham Farms, MI, United States, ⁴Wayne State University, Detroit, MI, United States

Patients with Parkinson’s disease (PD) showed increased iron deposition in the substantia nigra, red nucleus, dentate nucleus and globus pallidus compared with healthy controls. Besides, the T1 value, T2* value and R2* value of deep nucleus also altered in PD patients. Which suggested the STrategically Acquired Gradient Echo (STAGE) imaging could provide a good performance in quantitative analysis in multi-modal parameters.

Virendra R Mishra¹, Karthik R Sreenivasan¹, Jessica Caldwell², Aaron Ritter³, and Zoltan K Mari^3
1Imaging, Cleveland Clinic Lou Ruvo Center for Brain Health, Las Vegas, NV, United States, ²Neuropsychology, Cleveland Clinic Lou Ruvo Center for Brain Health, Las Vegas, NV, United States, ³Neurology, Cleveland Clinic Lou Ruvo Center for Brain Health, Las Vegas, NV, United States

Diffusion MRI (dMRI) could be used to understand cognitive impairment in Parkinson’s disease (PD). However, single-tensor (ST)-derived fractional anisotropy (FA) measures are biased due to the presence of crossing-fibers and contamination from cerebrospinal fluid (CSF). CSF contamination can be corrected by fitting a bi-tensor model to estimate free water (FW) contamination. Hence, in this study, we compared FW and FW-corrected ST dMRI-derived measures between PD patients (with and without cognitive impairment) and healthy controls (HC) estimated with multishell dMRI data. Our analysis suggests that FW-corrected dMRI analyses are more powerful in understanding WM disorganization in PD patients with cognitive impairment. 

LYDIA CHOUGAR^1,2, EMINA ARSOVIC¹, RAHUL GAURAV³, EMMA BIONDETTI⁴, NADYA PYATIGORSKAYA¹, and STEPHANE LEHERICY^1
1PITIE SALPETRIERE, PARIS, France, ²PARIS BRAIN INSTITUTE, PARIS, France, ³Paris Brain Institute, PARIS, France, ⁴Università degli Studi "G. d'Annunzio" Chieti, CHIETI, Italy

We investigated the regional selectivity of neurodegenerative changes in the SNc in patients with Parkinson’s disease (PD) and atypical parkinsonism using neuromelanin-sensitive MRI. We confirmed that neuromelanin volume and signal were reduced in parkinsonian disorders. The spatial pattern of changes differed between progressive supranuclear palsy (PSP) and synucleinopathies. Compared to healthy controls (HC), subjects with PD and multisystem atrophy (MSA), PSP subjects had greater changes in the associative region. Signal-to-noise in the sensorimotor territory was preserved in PSP, but reduced in PD patients and there was a trend in MSA patients. There was no significant difference between MSA and PD.

Jia Yan Shi¹ and Hua Jun Chen^2
1Fujian Medical University Union Hospital, Fuzhou, China, ²Radiology, Fujian Medical University Union Hospital, Fuzhou, China

We conducted the first assessment of the sensorimotor-related areas(SMA) alterations in ALS using IVIM MRI and atlas-based analysis, which may provide useful information for localization of specific cortex and white matter(WM) tract damage in ALS. In grey matter areas (GM), ALS patients showed a reduction in f in the bilateral preSMA and SMA, while in WM areas, ALS patients exhibited an increase in D in a WM tract projecting to the right ventral premotor cortex(PMv).  Correlation analysis revealed that the average D in this right PMv tract was negatively correlated to ALS disease severity. 

Pohchoo Seow¹, Yao-Chia Shih², Septian Hartono³, Li Rong Yin¹, Aeden Zi Cheng Kuek¹, Samuel Yong Ern Ng³, Eng King Tan³, Louis Tan³, and Ling Ling Chan^1
1Diagnostic Radiology, Singapore General Hospital, Singapore, Singapore, ²Graduate Institute of Medicine, Yuan Ze University, Taipei, Taiwan, ³Neurology, National Neuroscience Institute, Singapore, Singapore

Vast evidence for network-level functional dysfunctions have been reported in Parkinson’s disease (PD). However, brain abnormalities that underlie common autonomic symptoms in PD have not been fully investigated. Resting-state functional integration of the Central Autonomic Network (CAN) of 79 PD patients and 43 healthy controls (HC) were evaluated using seed-based analysis. Significantly decreased functional connectivity between the right anterior insular seed and left lateral occipital cortex, right lingual gyrus, and left occipital pole were found in HC compared to PD. Functional connectivity analysis of the CAN facilitates further understanding of the potential mechanisms underlying altered autonomic regulation in PD.

Karthik R Sreenivasan¹, Xiaowei Zhuang¹, Jessica Caldwell¹, Aaron Ritter¹, Dietmar Cordes¹, Zoltan Mari¹, and Virendra Mishra^1
1Cleveland Clinic Lou Ruvo Center for Brain Health, Las Vegas, NV, United States

The underlying cause of cognitive deficits in PD (PD-MCI) is not well understood and there are no biomarkers to diagnose PD-MCI. Although previous studies have found disrupted functional connectivity several factors make it difficult to generalize findings from fMRI studies. In the current study, we investigate functional network abnormalities in PD-MCI and PD patients who are cognitively normal (PD-NC). Our results were in line with earlier studies that showed altered connectivity was observed involving the frontal and striatal regions in the PD-MCI group, and we also found altered connectivity between regions in the temporal and the parietal cortex.

Apoorva Safai¹, Shweta Prasad^2,3, Jitender Saini⁴, Abhishek Lenka², Pramod Pal², and Madhura Ingalhalikar^1
1Symbiosis Centre for Medical Image Analysis, Symbiosis International University, Pune, India, ²Department of Neurology, National Institute of Mental Health & Neurosciences, Bangalore, India, ³Department of Clinical Neuroscience, National Institute of Mental Health & Neurosciences, Bangalore, India, ⁴Department of Neuroimaging & Interventional Radiology, National Institute of Mental Health & Neurosciences, Bangalore, India

Visual hallucinations (VH) is a commonly occurring psychosis symptom in Parkinson’s disease (PD). However, neuropathology of VH in PD is not clearly known, thereby limiting the efficacy of therapeutic strategies. To mitigate this gap, we evaluated functional connectivity (FC) changes and network organisation, related to VH in PD. PD patients exhibited widespread reduction in interhemispheric FC and local network topology of temporal, frontal, parietal, striatal, limbic, cerebellar, occipital and sensory motor regions. Patients with psychosis displayed larger FC reductions, particularly in cerebellar regions and their connections with frontal and occipital regions. Topological changes in temporal regions seen across PD patients