Keywords: Parkinson's Disease, Elastography

Motivation: MR Elastography (MRE) of the brain is a novel technique that elucidates the viscoelastic properties of the brain. Changes in e.g. stiffness of various brain regions often occur at an early stage in neuropathologies.

Goal(s): Assessing how viscoelastic properties of the brain changes with Parkinson’s disease, and study the microstructural mechanisms behind these changes.

Approach: We investigated how the viscoelasticity of the brain changes for diseased subjects compared to controls (21 subjects), and correlated these changes with microstructural properties (based on multidimensional diffusion imaging).

Results: We found a softening effect of the occipital and temporal lobes, possibly correlated with early neural atrophy.

Impact: The presented results show how PD affects the brain in a new combination of modalities which can help to better understand the pathology, which may, for example, lead to new methods for early PD diagnosis.

Keywords: Other Neurodegeneration, High-Field MRI, Surgical Planning, Essential Tremor, Deep Brain Stimulation, Neuromodulation

Motivation: 7T MRI offers improved image quality for deep brain stimulation (DBS) targeting, but greater distortion and artifacts that could lead to inaccurate targeting. 

Goal(s): Our goal was to compare outcomes in DBS for essential tremor between patients targeted using 3T versus 7T MRI.

Approach: Retrospective comparison of DBS patients with ET was performed with patients targeted using 3T versus 7T MRI. We assessed differences in tremor improvement, adverse events, and electrode positioning. 

Results: ET DBS patients targeted with 7T had significantly greater tremor control compared to 3T, as well as lower stimulation currents and improved electrode precision.

Impact: Despite challenges of 7T MRI in surgical planning, outcomes in DBS for ET were improved by use of 7T MRI versus 3T MRI, including better tremor control, reduced stimulation currents, and greater precision.

Keywords: Parkinson's Disease, Parkinson's Disease

Motivation: The neurovascular changes associated with cognitive decline in Parkinson’s disease (PD) remain uncertain. Like Alzheimer’s disease, blood flow integrity may also play a significant role in maintaining cognitive function in PD.

Goal(s): To understand the relationship between cognitive impairment and circle of Willis anatomy and haemodynamics in PD.

Approach: 36 healthy controls and 81 individuals with PD completed 3T 4D flow MRI acquisition and an extensive neuropsychological battery.

Results: The PD group showed 10% lower total cerebral blood flow (ml/min) and 7% lower flow velocity (cm/min) which were associated with poorer cognition.

Impact: 4D flow MRI revealed hypoperfusion of the circle of Willis in Parkinson’s disease which corresponded with poorer cognition. These results support future targeting of vascular mechanisms to alleviate cognitive impairment in Parkinson’s disease.   

Keywords: Parkinson's Disease, Parkinson's Disease

Motivation: Parkinson's disease is the fastest growing neurological disorder. However, comorbidities of the disease complicates its diagnosis and creates need for the discovery more biomarkers to help with diagnosis.

Goal(s): Our aim is to noninvasively measure the cerebral oxygen extraction fraction which is an important metric for cerebral oxygen metabolism and see if it can be utilized as a biomarker for early Parkinson's Disease.

Approach: MRI scans from early Parkinson's patients and healthy controls were obtained. Oxygen extraction fraction (OEF) maps for subjects were generated and two groups' oxygen metabolism was compared.

Results: An overall increase in cerebral OEF was observed for Parkinson's patients.

Impact: This study will potentially help with the diagnosis of early Parkinson's by providing another quantifiable biomarker. Additionally, difference in oxygen metabolism can help to understand Parkinson's disease better.

Keywords: Parkinson's Disease, Parkinson's Disease, Denoising

Motivation: SandwichNM is an advanced neuromelanin sensitive MRI method, but it use the same sequence twice and averages them to increase signal-to-noise ratio (SNR) requiring long scan time.

Goal(s): The objective is to preserve the SNR while reducing two scans into a single scan.

Approach: We proposed deep learning-based denoising method for sandwichNM image to reduce the number of scans.

Results: The proposed model achieved an increased PSNR and SSIM with utilizing single scan, which has reduced the scan time to half of the previous one.

Impact: SandwichNM is an advanced neuromelanin sensitive MRI technique but requires averaging two scans due to SNR issue. The proposed method enabled higher SNR from single scan which can be useful for scanning patients with Parkinson's disease with involuntary movements.

Keywords: Parkinson's Disease, Parkinson's Disease, 7T; Neuromelanin imaging; reduced FOV

Motivation:  In neuromelanin (NM) imaging at 7T, placing bilateral sagittal saturation bands near the midbrain can mitigate ghosting artifacts and provide equivalent MT contrast compared to traditional MT pulses. 

Goal(s): To present the feasibility of a proposed simultaneous dual-band saturation scheme to provide MT contrast in NM imaging at 7T.

Approach: Simultaneous dual-band saturation pulse was designed for the proposed simultaneous saturation scheme. Its performance in providing MT contrast was compared to the conventional sequential scheme for 3D GRE- and PETRA-based in-vivo NM imaging. 

Results: The proposed simultaneous dual-band saturation schemes yielded favorable contrast between the NM-rich SNpc and the surrounding tissues. 

Impact: The proposed simultaneous dual-band saturation scheme can provide symmetric saturation and MT effects in high-resolution rFOV NM imaging at 7T. The proposed scheme may also work for efficient out-of-volume suppression for MRS and blood suppression in certain MR applications.  

Keywords: Parkinson's Disease, White Matter

Motivation: White matter damage has been known to accumulate prior to the onset of white matter hyperintensity, but there is currently no way to calculate the extent of damage.

Goal(s): Quantification of high-water content regions in Parkinson's patients based on proton spin density maps provides a new biomarker for mapping tissue damage and interpretation of WMH evolution.

Approach: Distribution of high-water content regions and WMH were mapped for Parkinson patients with different cognitive levels. Heatmaps were created for groups.

Results: High water content regions were mainly distributed along the ventricular wall. Water content and WMH correlated with CSF volumes with significant differences between groups.

Impact: Segmentation of the high-water content regions based on proton spin density maps provides the ability to interpret WMH evolution and provide a new potential biomarker to guide the early detection. These effects were dramatically seen in Parkinson’s patients with dementia.

Keywords: Parkinson's Disease, Neuroscience

Motivation: Functional connectivity between white-matter networks maybe a neuroimaging biomarker of PD with  L-dopa induced dyskinesia (LID).

Goal(s): The aim of this research is to investigate changes of the white-matter functional networks in PD with LID.

Approach: The construction of white-matter network was achieved by using K-means clustering while FC was also calculated.

Results: A decreasing trend (not significant) was also found between LID and noLID group. FC between WM2 and WM11 in LID group showed a significantly positive correlation with MMSE, while a negative relation between FC and MMSE was found in noLID group.

Impact: The study showed that decreased FC between white-matter networks and their influence on clinical performance may indicated the appearance of PD and symptom of LID.

Keywords: Parkinson's Disease, Brain, quantitative susceptibility mapping (QSM), Parkinson's, nigra, basal ganglia, REM Sleep Behavior Disorder, Iron, linear mixed-effects models

Motivation: Although Parkinson’s disease (PD) and isolated REM sleep behavior disorder (iRBD) demonstrate elevated substantia nigra (SN) iron concentration, topography of change is still debated.

Goal(s): To quantify abnormal brain iron progression over time using quantitative susceptibility mapping (QSM).

Approach: Subjects were assessed three times 2 years apart. Mean QSM template was developed to quantify SN and its subdivisions, and subthalamic nucleus. Then caudate nucleus, putamen, globus pallidus and thalamus were also quantified.

Results: At baseline, PD without RBD demonstrated +17.8% posteroventral SN iron overload and during the follow-up, 26.2% overload versus controls.
None of the other tested regions showed significant differences between groups.

Impact: Abnormal iron concentration was only found in the posteroventral SN and not in any other basal ganglia region over time. Further, PD without RBD showed highest iron concentration. Iron-sensitive quantitative MRI could be a potential longitudinal biomarker of the future.

Keywords: Other Neurodegeneration, Neurodegeneration

Motivation: To improve understanding of disease progression in four-repeat tauopathies and determine the value of MRI to predict specific pathologies. 

Goal(s): To estimate spatiotemporal atrophy progression patterns from 3D structural MRI and to examine the relationship between the atrophy patterns and pathological diagnosis in four repeat tauopathies.

Approach: We applied an unsupervised machine learning algorithm called Subtype and Stage Inference (SuStaIn) to 3D structural MRI images in autopsy-confirmed four-repeat tauopathies.

Results: The estimated subtype correlated well with the pathological diagnosis, and the estimated stage was negatively correlated with time from MRI to death.

Impact: We identified two MRI atrophy subtypes with different patterns of progression that correlated to pathology in autopsy-confirmed four-repeat tauopathies. This improves understanding of how these pathologies spread through the brain and suggests that MRI could help predict pathology during life. 

Keywords: Dementia, Multi-Contrast, Locus Coeruleus, Magnetisation transfer, Ultra-high field, Neurodegeneration

Motivation: Magnetisation transfer (MT) weighting has been used to visualise the Locus Coeruleus (LC) at 7T, but robust visualisation remains challenging due to its small size and complex contrast mechanisms.

Goal(s): Investigate how proton-density- (PD) and T1-weighting interact with MT-weighting and optimise an advanced post-processing pipeline for LC visualisation.

Approach: Multi-echo 3D gradient echo images were acquired with MT-weighting and either PD- or T1-weighting from two individuals, including scan-rescan acquisitions.

Results: MT-PD-weighting enhanced visualisation of the LC with respect to the surrounding tissue, whereas MT-T1-weighting enhanced contrast with respect to the nearby CSF. Combining these via wavelet-based fusion maximises these respective benefits.

Impact: Enhancing visualisation of the Locus Coeruleus with our proposed acquisition and processing technique will pave the way for neurologists and cognitive neuroscientists to understand the key role this structure plays in human cognition and neurodegeneration.

Keywords: Parkinson's Disease, Parkinson's Disease, 7T; Neuromelanin imaging; reduced FOV; 3D GRE; SNc; LC; MT; Saturation band

Motivation: GRE based neuromelanin (NM) imaging at 7T is sensitive to B0 field disturbance by patient breathing or even mild head motion.

Goal(s): A reduced FOV method is proposed for 7T NM imaging using 3D GRE with three saturation bands for creating MT contrast and reducing ghosting artifacts.

Approach: The sequence has bilateral sagittal saturation bands placed in close proximity to the SNc for artifacts and FOV reduction, and the 3rd axial saturation band placed below the SNc for arterial blood suppression. 

Results: The method yields higher resolution, enhanced NM contrast, and a reduction in artifacts.

Impact: The reduced FOV neuromelanin (NM) imaging method using three saturation bands offers higher resolution NM imaging at 7T with improved NM contrast and image quality.

Keywords: Parkinson's Disease, Arterial spin labelling, Parkinson’s disease; PD-related perfusion pattern; levodopa reactivity

Motivation: A kind of perfusion biomarker capable of effectively distinguishing Parkinson's disease (PD) from normal subjects and reflecting motor dysfunction and levodopa reactivity is under research.

Goal(s): To construct a stable PD-related perfusion pattern based on arterial spin labelling (ASL), and to explore levodopa reactivity of motor symptoms with the pattern.

Approach: Principal component analysis and the scaled sub-profile model (PCA-SSM) was used to construct and validate PD-related perfusion pattern, with correlation and predictive analysis.

Results: The PD-related perfusion pattern was constructed to predict the severity of motor symptoms and assess levodopa reactivity in PD patients with axial symptom.

Impact: The PD-related perfusion pattern could serve as a potential biomarker for evaluating the severity of motor symptoms and the prognosis of levodopa therapy in PD patients with axial symptom.

Keywords: Parkinson's Disease, Neuroscience

Motivation: STN-targeted DBS shows promise in Dystonia treatment. However, optimal stimulation sites, pathway modulation, and network effects for different dystonia subtypes are unknown.

Goal(s): To examine stimulation sites, pathway modulation, and network effects in dystonia subtypes for personalized DBS interventions.

Approach: Retrospective study of 71 dystonia patients undergoing STN-DBS. Clinical outcomes assessed with Burke-Fahn-Marsden Dystonia Rating Scale. Imaging, tissue activation estimation, and pathway/network reconstruction performed using Lead-DBS and Iso2Mesh toolbox.

Results: Subtypes have varied stimulation sites. Orofacial group shows positive correlations between VTA-STN intersection and clinical improvement. Dorsolateral STN effective for orofacial and hindlimb symptoms. Targeting lenticular fasciculus benefits orofacial dystonia.

Impact: Study proposes a comprehensive model for personalized DBS, improving treatment strategies. Further research needed to validate targets, pathways, and networks, enhancing clinical decision-making and outcomes.

Keywords: Parkinson's Disease, Parkinson's Disease, VMAT2, striatum, iron

Motivation: The limited availability and high cost of ¹⁸F-AV133 PET impedes its widespread adoption for use in diagnosis of Parkinson’s disease.

Goal(s): Our goal was to assess the relationship between ¹⁸F-AV133 PET and MRI imaging markers in Parkinson's disease.

Approach: Magnetization transfer and relaxometry imaging metrics derived in the basal ganglia of Parkinson's disease patients were compared to standardized uptake ratios from ¹⁸F-AV133 PET.

Results: Significant correlations were seen between ¹⁸F-AV133 PET and MRI imaging metrics. These results suggest that MRI is able to capture neurodegenerative processes in Parkinson's disease.

Impact: Our demonstration of the relationship between ¹⁸F-AV133 PET and MRI imaging markers suggests MRI imaging markers may serve as a surrogate measure for the integrity of the nigrostriatal system in Parkinson's disease.

Keywords: Parkinson's Disease, Neurodegeneration

Motivation: Multiple system atrophy (MSA) and Parkinson’s disease (PD) are sharing many common clinical presentations. The clinical diagnosis has been empirical due to a lack of a subjective imaging biomarker.

Goal(s): To investigate possible NM change in the SN and to better facilitate differential diagnosis.

Approach: 38 MSA , 38 PD patients and 38 HCs were scanned on a 3T MRI system. We calculated the relative contrast ratio (rCR) and NM volume of bilateral SN.

Results: HCs had higher rCR and NM volume than patients with PD and MSA (p＜0.001). Of note, patients with MSA had lower NM volume than patients with PD (p＜0.001).

Impact: Our finding suggests that NM degeneration and depigmentation of SN may be more severe in patients with MSA in comparison with PD. Hence, NM measures of the SN may provide promising insight into differentiating MSA and PD.