New and reliable MRI diagnosis for progressive supranuclear palsy

Argyrophilic Grain Disease Clinically Presenting as Progressive Supranuclear Palsy with Progressive Gait Freezing

BACKGROUND

Argyrophilic grain disease (AGD) is a four-repeat tauopathy characterized by the accumulation of argyrophilic grains. Its primary clinical manifestation is late-onset amnestic dementia. While the extension of argyrophilic grains to the substantia nigra may be related to its potential association with parkinsonism, biochemical analyses are lacking.

OBJECTIVES

To elucidate the extent of AGD to the midbrain, including the substantia nigra, using histopathological examination and biochemical analysis in a pathologically proven case of AGD presenting with parkinsonism and cognitive impairment.

METHODS

We describe the case of a patient suggestive of progressive supranuclear palsy. Neuropathological and biochemical investigations were performed.

RESULTS

Neurological examination of an 80-year-old man with a 6-year history of gait disturbance revealed parkinsonism, including gait freezing, postural instability, bradykinesia, and cognitive impairment. The patient was diagnosed with progressive supranuclear palsy with progressive gait freezing. Five years later, the patient reported falling backward repeatedly, became wheelchair-bound, and died of pneumonia. Macroscopic observations revealed marked amygdala atrophy. Microscopic findings revealed argyrophilic grains in the limbic system, compatible with Saito stage III, as well as in the substantia nigra and midbrain tegmentum. Western blotting showed an AGD-specific band pattern, and immunoelectron microscopy analyses showed an AGD-specific tau filament of abnormally phosphorylated tau in both the nucleus accumbens and midbrain.

CONCLUSIONS

This report further confirmed that AGD presents with parkinsonism, commensurate with AGD pathology and biochemical findings extending to the midbrain. Therefore, AGD should be considered in the differential diagnosis of cases presenting with parkinsonism and cognitive impairment in the older population.

Does Midbrain Atrophy Distinguish Progressive Supranuclear Palsy from Frontotemporal Dementia?

BACKGROUND

The diagnostic value of midbrain atrophy for distinguishing behavioral variant frontotemporal dementia (bvFTD) from progressive supranuclear palsy (PSP) is unclear.

OBJECTIVE

To investigate whether measures of midbrain atrophy differentiate PSP from bvFTD.

METHODS

We included four groups: healthy controls (n = 19), PSP-Richardson syndrome (n = 20), bvFTD (n = 19) and Parkinson's disease (PD; n = 12). The following quantitative and qualitative measures were calculated: Hummingbird sign rating scale [HBS-RS], global midbrain atrophy [GMA], midbrain area, midbrain/pons ratio, the Magnetic Resonance Parkinsonism Index (MRPI), the MRPI 2.0 and brainstem volume.

RESULTS

Compared to controls, PSP and bvFTD had lower values of midbrain area, HBS-RS and GMA, and higher MRPI and MRPI 2.0. HBS-RS, GMA, midbrain/pons ratio, midbrain area, MRPI, MRPI 2.0 and brainstem volume distinguished PSP from bvFTD with 73%, 67%, 75%, 83%, 71%, 69% and 82% accuracies, respectively.

CONCLUSIONS

Both quantitative and qualitative measures of midbrain atrophy provided modest accuracy in distinguishing PSP from bvFTD.

Idiopathic normal pressure hydrocephalus concomitant with progressive supranuclear palsy

INTRODUCTION

Recent studies by us and others have unveiled a frequent coexistence of idiopathic normal pressure hydrocephalus (iNPH) with neurodegenerative movement disorders, including progressive supranuclear palsy (PSP). This study aims to explore the clinical and radiological characteristics of patients with iNPH who also had comorbid with PSP, referred to as iNPHc + PSP.

METHODS

We retrospectively analyzed patients with iNPH admitted to our department between 2009 and 2024. We adhered to the established clinical criteria for iNPH and the Movement Disorder Society (MDS)-PSP criteria for probable or possible PSP with minor modifications.

RESULTS

Among 85 iNPH patients, 18 were categorized as having iNPHc + PSP (21.2 %). Clinically, comorbid PSP led to impaired vertical eye movement, axial-dominant parkinsonism, and a propensity to fall backward in iNPH (p = 0.022, p = 0.002, and p < 0.005, respectively). Radiologically, comorbid PSP demonstrated a shortened mesencephalic tegmentum length in the magnetic resonance imaging and an asymmetrical deficit of dopamine transporter activities in the DaTscan (p = 0.0005, p = 0.0129, respectively). Lumboperitoneal shunt (LPS) surgery improved the modified Rankin scale (p = 0.038) and the iNPH grading scale (total score, p = 0.003; gait disturbance, p = 0.020; urinary incontinence, p = 0.026) one-year after surgery.

CONCLUSIONS

PSP can coexist with iNPH, and detailed clinical and radiological assessment can aid in detecting this comorbidity. Importantly, LPS surgery can improve outcomes of patients with iNPHc + PSP.

Brainstem and cerebellar radiological findings in progressive supranuclear palsy

Progressive supranuclear palsy is a sporadic neurodegenerative 4-repeat tauopathy associated with significant morbidity. Heterogeneity of symptom expression among this group is increasingly recognized, reflecting variable tau spread and neurodegeneration. Clinical manifestations consist of debilitating and rapidly progressive motor, oculomotor, speech, cognitive and affective impairments. Core pathological changes are noted with a predominance in the midbrain and basal ganglia; however, spread to the more caudal brainstem and cerebellar regions is reported at various stages. Accordingly, whilst midbrain atrophy is the best recognized supportive imaging finding, quantitative neuroimaging studies using MRI and PET approaches have revealed a wider profile of brain abnormalities in cohorts of individuals with progressive supranuclear palsy. This expanded neurobiological scope of disease may account for individual heterogeneity and may highlight additional biological markers that are relevant to diagnosing and tracking the illness. Additionally, there is increasing understanding of the diverse cognitive, affective and speech functions of the cerebellum, which may be implicated in progressive supranuclear palsy beyond current recognition. In this review, we undertake a systematic literature search and summary of in vivo structural and functional neuroimaging findings in the brainstem and cerebellum in progressive supranuclear palsy to date. Novel and multimodal imaging techniques have emerged over recent years, which reveal several infratentorial alterations beyond midbrain atrophy in progressive supranuclear palsy. Most saliently, there is evidence for volume loss and microstructural damage in the pons, middle cerebellar peduncles and cerebellar cortex and deep nuclei, reported alongside recognized midbrain and superior cerebellar peduncle changes. Whilst the literature supporting the presence of these features is not unanimous, the evidence base is compelling, including correlations with disease progression, severity or variant differences. A smaller number of studies report on abnormalities in MRI measures of iron deposition, neuromelanin, viscoelasticity and the glymphatic system involving the infratentorial regions. Molecular imaging studies have also shown increased uptake of tau tracer in the midbrain and cerebellar dentate nucleus, although concern remains regarding possible off-target binding. Imaging of other molecular targets has been sparse, but reports of neurotransmitter, inflammatory and synaptic density alterations in cerebellar and brainstem regions are available. Taken together, there is an established evidence base of in vivo imaging alterations in the brainstem and cerebellum which highlights that midbrain atrophy is often accompanied by other infratentorial alterations in people with progressive supranuclear palsy. Further research examining the contribution of these features to clinical morbidity and inter-individual variability in symptom expression is warranted.

Possible Impact of Peripheral Inflammatory Factors and Interleukin-1β (IL-1β) on Cognitive Functioning in Progressive Supranuclear Palsy-Richardson Syndrome (PSP-RS) and Progressive Supranuclear Palsy-Predominant Parkinsonism (PSP-P)

Progressive supranuclear palsy (PSP) is a tauopathic atypical parkinsonian syndrome. Recent studies suggest that inflammation may play a role in PSP pathogenesis, highlighting markers like the neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and cytokines such as IL-1β and IL-6. This study aimed to assess the relationship between peripheral inflammatory markers and psychological abnormalities in PSP-RS and PSP-P patients. The study included 24 participants: 12 with PSP-RS, 12 with PSP-P, and 12 controls. Cognitive function was assessed using the Montreal Cognitive Assessment (MoCA); however, the executive functions were evaluated using the Frontal Assessment Battery (FAB), while inflammatory markers such as IL-1β, IL6, NLR, and PLR were measured. The parameter correlation was executed using Spearman's correlation (rs). The analysis revealed significant negative correlations between NLR and MoCA (rs = -0.48), as well as between PLR and MoCA (rs = -0.60). The negative correlation between IL-1β and MoCA was statistically significant but relatively weak. This study highlights the relevance of inflammatory markers such as NLR and PLR in reflecting cognitive decline in PSP patients, with IL-1β potentially playing a protective role in cognitive function.

Long-standing preservation of levodopa response in progressive supranuclear palsy

The clinical and neuropathological characteristics of progressive supranuclear palsy (PSP) with preservation of levodopa (L-dopa) response are described in this report. We present the case of a 73-year-old Japanese man with a 13-year history of dopa-responsive Parkinsonism and abnormalities observed in metaiodobenzylguanidine (MIBG) myocardial scintigraphy, suggesting Parkinson's disease. However, autopsy results revealed PSP pathology, including tuft-shaped astrocytes and globose-type neurofibrillary tangles, without Lewy body pathology. The degeneration was moderately to severely distributed in the globus pallidus, subthalamic nucleus, and substantia nigra, whereas striatal degeneration was mild. These findings suggest an intact response to L-dopa therapy throughout the patient's lifetime. Pathological examination of cardiac sympathetic nerves revealed intact nerves, suggesting functional involvement in the MIBG abnormality. This study provides further evidence of the clinical and pathological heterogeneity of PSP. Homozygosity for both the rs564309-C allele at TRIM11 and the rs2242367-G allele at SLC2A13 might have played a protective role. This case indicates a protracted course-PSP, which may hold promise for future treatments.

Frequent and Unexplained Falls: A Case of Progressive Supranuclear Palsy

Progressive supranuclear palsy (PSP) is the most common neurodegenerative form of atypical parkinsonism. Although its prevalence has increased recently, it remains underdiagnosed. PSP is characterized by parkinsonism, downward gaze disorder, and a tendency to fall due to degeneration of the basal ganglia, brain stem, and cerebellum. Various clinical presentations have been linked to this entity, often making its diagnosis difficult, which can take three to four years to be established. PSP diagnosis mainly relies on clinical data and can only be confirmed with the neuropathological findings at autopsy. However, as per recent research, neuroimaging, namely brain MRI, can aid in an earlier diagnosis. We report the case of an 85-year-old female with a history of recurrent and unexplained falls over the last two years that had been wrongly attributed to Parkinson's disease (PD). She initially presented complaining of recurring falls associated with retropulsion movements that got progressively worse and eventually was not able to walk on her own. Concomitantly, there was also a cognitive dysfunction with frontal predominance. An exhaustive physical examination and clinical history revealed indicators consistent with PSP. PSP diagnosis demands a high clinical suspicion, and hence clinicians should have a good understanding of this disease for its early recognition. Although it is a devastating disorder, and no medications that can reverse the disease course are currently available, early diagnosis of PSP may contribute to improving the quality of life of the patients and their families, and prevent complications. This report highlights the clinically significant improvement in motor and neuropsychiatric symptoms when a multidisciplinary medical team is involved in the care of a PSP patient.

Correlation between clinical and neuropathological subtypes of progressive supranuclear palsy

INTRODUCTION

Progressive supranuclear palsy (PSP) is characterized by pathology prominently in the basal ganglia, the tegmentum of the brainstem, and the frontal cortex. However, pathology varies according to clinical features. This study aimed to statistically verify the correspondence between the clinical and pathological subtypes of PSP.

METHODS

We identified patients with a pathological diagnosis of PSP and classified the eight clinical subtypes of the Movement Disorders Society criteria for the clinical diagnosis of PSP (MDS-PSP criteria) into the Richardson, Akinesia, and Cognitive groups. We used anti-phosphorylated tau antibody immunostaining to semi-quantitatively evaluate neurofibrillary tangles (NFTs) and coiled bodies/threads (CB/Ths) in the globus pallidus, subthalamic nucleus, and midbrain tegmentum. In the frontal cortex, tufted astrocytes (TAs) and CB/Ths were assessed on a 3-point scale. We compared the pathology among the three groups, recorded the phenotypes ranked the second and lower in the multiple allocation extinction rule and examined whether the pathology changed depending on applying each phenotype.

RESULTS

The Richardson group exhibited severe NFTs and CB/Ths in the midbrain tegmentum. The Akinesia group showed severe NFTs in the globus pallidus. The Cognitive group had severe TAs and CB/Ths in the frontal cortex. TAs and CB/Ths in the frontal cortex correspond to behavioral variant frontotemporal dementia, and supranuclear vertical oculomotor palsy.

CONCLUSION

These clinical symptoms may reflect the distribution of tau pathologies in PSP.

Asymmetry in Atypical Parkinsonian Syndromes-A Review

Background/Objectives: Atypical parkinsonian syndromes (APSs) are a group of neurodegenerative disorders that differ from idiopathic Parkinson's disease (IPD) in their clinical presentation, underlying pathology, and response to treatment. APSs include conditions such as multiple system atrophy (MSA), progressive supranuclear palsy (PSP), corticobasal syndrome (CBS), and dementia with Lewy bodies (DLB). These disorders are characterized by a combination of parkinsonian features and additional symptoms, such as autonomic dysfunction, supranuclear gaze palsy, and asymmetric motor symptoms. Many hypotheses attempt to explain the causes of neurodegeneration in APSs, including interactions between environmental toxins, tau or α-synuclein pathology, oxidative stress, microglial activation, and vascular factors. While extensive research has been conducted on APSs, there is a limited understanding of the symmetry in these diseases, particularly in MSA. Neuroimaging studies have revealed metabolic, structural, and functional abnormalities that contribute to the asymmetry in APSs. The asymmetry in CBS is possibly caused by a variable reduction in striatal D2 receptor binding, as demonstrated in single-photon emission computed tomography (SPECT) examinations, which may explain the disease's asymmetric manifestation and poor response to dopaminergic therapy. In PSP, clinical dysfunction correlates with white matter tract degeneration in the superior cerebellar peduncles and corpus callosum. MSA often involves atrophy in the pons, putamen, and cerebellum, with clinical symmetry potentially depending on the symmetry of the atrophy. The aim of this review is to present the study findings on potential symmetry as a tool for determining potential neuropsychological disturbances and properly diagnosing APSs to lessen the misdiagnosis rate. Methods: A comprehensive review of the academic literature was conducted using the medical literature available in PubMed. Appropriate studies were evaluated and examined based on patient characteristics and clinical and imaging examination outcomes in the context of potential asymmetry. Results: Among over 1000 patients whose data were collected, PSP-RS was symmetrical in approximately 84% ± 3% of cases, with S-CBD showing similar results. PSP-P was symmetrical in about 53-55% of cases, while PSP-CBS was symmetrical in fewer than half of the cases. MSA-C was symmetrical in around 40% of cases. It appears that MSA-P exhibits symmetry in about 15-35% of cases. CBS, according to the criteria, is a disease with an asymmetrical clinical presentation in 90-99% of cases. Similar results were obtained via imaging methods, but transcranial sonography produced different results. Conclusions: Determining neurodegeneration symmetry may help identify functional deficits and improve diagnostic accuracy. Patients with significant asymmetry in neurodegeneration may exhibit different neuropsychological symptoms based on their individual brain lateralization, impacting their cognitive functioning and quality of life.

Simple biomarkers to distinguish Parkinson's disease from its mimics in clinical practice: a comprehensive review and future directions

In the last few years, a plethora of biomarkers have been proposed for the differentiation of Parkinson's disease (PD) from its mimics. Most of them consist of complex measures, often based on expensive technology, not easily employed outside research centers. MRI measures have been widely used to differentiate between PD and other parkinsonism. However, these measurements were often performed manually on small brain areas in small patient cohorts with intra- and inter-rater variability. The aim of the current review is to provide a comprehensive and updated overview of the literature on biomarkers commonly used to differentiate PD from its mimics (including parkinsonism and tremor syndromes), focusing on parameters derived by simple qualitative or quantitative measurements that can be used in routine practice. Several electrophysiological, sonographic and MRI biomarkers have shown promising results, including the blink-reflex recovery cycle, tremor analysis, sonographic or MRI assessment of substantia nigra, and several qualitative MRI signs or simple linear measures to be directly performed on MR images. The most significant issue is that most studies have been conducted on small patient cohorts from a single center, with limited reproducibility of the findings. Future studies should be carried out on larger international cohorts of patients to ensure generalizability. Moreover, research on simple biomarkers should seek measurements to differentiate patients with different diseases but similar clinical phenotypes, distinguish subtypes of the same disease, assess disease progression, and correlate biomarkers with pathological data. An even more important goal would be to predict the disease in the preclinical phase.

MRI-ARSACS: An Imaging Index for Autosomal Recessive Spastic Ataxia of Charlevoix-Saguenay (ARSACS) Identification Based on the Multicenter PROSPAX Study

BACKGROUND

Autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS) and hereditary spastic paraplegia type 7 (SPG7) represent the most common genotypes of spastic ataxia (SPAX). To date, their magnetic resonance imaging (MRI) features have only been described qualitatively, and a pure neuroradiological differential diagnosis between these two conditions is difficult to achieve.

OBJECTIVES

To test the performance of MRI measures to discriminate between ARSACS and SPG7 (as an index of common SPAX disease).

METHODS

In this prospective multicenter study, 3D-T1-weighted images of 59 ARSACS (35.4 ± 10.3 years, M/F = 33/26) and 78 SPG7 (54.8 ± 10.3 years, M/F = 51/27) patients of the PROSPAX Consortium were analyzed, together with 30 controls (45.9 ± 16.9 years, M/F = 15/15). Different linear and surface measures were evaluated. A receiver operating characteristic analysis was performed, calculating area under the curve (AUC) and corresponding diagnostic accuracy parameters.

RESULTS

The pons area proved to be the only metric increased exclusively in ARSACS patients (P = 0.02). Other different measures were reduced in ARSACS and SPG7 compared with controls (all with P ≤ 0.005). A cut-off value equal to 1.67 of the pons-to-superior vermis area ratio proved to have the highest AUC (0.98, diagnostic accuracy 93%, sensitivity 97%) in discriminating between ARSACS and SPG7.

CONCLUSIONS

Evaluation of the pons-to-superior vermis area ratio can discriminate ARSACS from other SPAX patients, as exemplified here by SPG7. Hence, we hereby propose this ratio as the Magnetic Resonance Index for the Assessment and Recognition of patients harboring SACS mutations (MRI-ARSACS), a novel diagnostic tool able to identify ARSACS patients and useful for discriminating ARSACS from other SPAX patients undergoing MRI. © 2024 International Parkinson and Movement Disorder Society.

Potential dopaminergic deficit in patients with geriatric psychiatric disorders as revealed by DAT-SPECT: a cross-sectional study

BACKGROUND

It has been reported that patients with geriatric psychiatric disorders include many cases of the prodromal stages of neurodegenerative diseases. Abnormal 123I-2β-carbomethoxy-3β-(4-iodophenyl)-N-(3-fluoropropyl) nortropane dopamine transporter single-photon emission computed tomography (DAT-SPECT) reveals a nigrostriatal dopaminergic deficit and is considered useful to detect dementia with Lewy bodies and Parkinson's disease as well as progressive supranuclear palsy and corticobasal degeneration. We aimed to determine the proportion of cases that are abnormal on DAT-SPECT in patients with geriatric psychiatric disorders and to identify their clinical profile.

METHODS

The design is a cross-sectional study. Clinical findings of 61 inpatients aged 60 years or older who underwent DAT-SPECT and had been diagnosed with psychiatric disorders, but not neurodegenerative disease or dementia were analysed.

RESULTS

36 of 61 (59%) had abnormal results on DAT-SPECT. 54 of 61 patients who had DAT-SPECT (89%) had undergone 123I-metaiodobenzylguanidine myocardial scintigraphy (123I-MIBG scintigraphy); 12 of the 54 patients (22.2%) had abnormal findings on 123I-MIBG scintigraphy. There were no cases that were normal on DAT-SPECT and abnormal on 123I-MIBG scintigraphy. DAT-SPECT abnormalities were more frequent in patients with late-onset (55 years and older) psychiatric disorders (69.0%) and depressive disorder (75.7%), especially late-onset depressive disorder (79.3%).

CONCLUSION

Patients with geriatric psychiatric disorders include many cases showing abnormalities on DAT-SPECT. It is suggested that these cases are at high risk of developing neurodegenerative diseases characterised by a dopaminergic deficit. It is possible that patients with geriatric psychiatric disorders with abnormal findings on DAT-SPECT tend to show abnormalities on DAT-SPECT first rather than on 123I-MIBG scintigraphy.

Progressive Supranuclear Palsy Diagnosed After a Severe Fall Trauma in a Patient Who Experienced Episodes of Easy Falling

Progressive supranuclear palsy (PSP) is characterized by parkinsonism, downward gaze disorder, and a tendency to fall due to degeneration of the basal ganglia, the brain stem, and the cerebellum. We report a case of PSP that was diagnosed following a traumatic hemopneumothorax caused by a fall while descending stairs. A 79-year-old man experienced lightheadedness and frequent falls for two years. He fell on stairs at home and was transferred to our hospital due to mobility issues. He was hospitalized and treated for traumatic hemopneumothorax. Neurological examination revealed vertical ocular motility disorder, positive Myerson's sign, increased muscle stiffness, and increased limb tendon reflexes. Brain MRI showed a hummingbird sign. In this case, a midbrain area of 58.1 mm2 was consistent with PSP. He had no medication history that could have caused falls. He was diagnosed with PSP based on clinical and imaging findings, and treatment with levodopa was initiated. Two months later, walking showed limited improvement, and living at home became difficult. He was discharged to a care facility. PSP is a risk factor for frequent falls in the elderly. PSP usually requires three to four years for diagnosis, although falls appear earlier than in other forms of degenerative parkinsonism. Additionally, PSP often results in repeated dynamic falls due to a decreased perception of danger associated with reduced frontal lobe function. As a result, the severity of trauma from falls in PSP tends to be higher than in other neurodegenerative diseases. Therefore, early diagnosis of PSP may help improve patients' quality of life and prevent trauma. Despite frequent falls over two years, the cause was not thoroughly investigated until the patient experienced severe trauma. The lesson from this case is the importance of a thorough neurological examination and sagittal MRI for elderly patients experiencing repeated falls, to consider the possibility of PSP. Furthermore, quantitative evaluation of MRI enhances the diagnostic accuracy of PSP.

Deep Learning-based Approach for Brainstem and Ventricular MR Planimetry: Application in Patients with Progressive Supranuclear Palsy

Purpose To develop a fast and fully automated deep learning (DL)-based method for the MRI planimetric segmentation and measurement of the brainstem and ventricular structures most affected in patients with progressive supranuclear palsy (PSP). Materials and Methods In this retrospective study, T1-weighted MR images in healthy controls (n = 84) were used to train DL models for segmenting the midbrain, pons, middle cerebellar peduncle (MCP), superior cerebellar peduncle (SCP), third ventricle, and frontal horns (FHs). Internal, external, and clinical test datasets (n = 305) were used to assess segmentation model reliability. DL masks from test datasets were used to automatically extract midbrain and pons areas and the width of MCP, SCP, third ventricle, and FHs. Automated measurements were compared with those manually performed by an expert radiologist. Finally, these measures were combined to calculate the midbrain to pons area ratio, MR parkinsonism index (MRPI), and MRPI 2.0, which were used to differentiate patients with PSP (n = 71) from those with Parkinson disease (PD) (n = 129). Results Dice coefficients above 0.85 were found for all brain regions when comparing manual and DL-based segmentations. A strong correlation was observed between automated and manual measurements (Spearman ρ > 0.80, P < .001). DL-based measurements showed excellent performance in differentiating patients with PSP from those with PD, with an area under the receiver operating characteristic curve above 0.92. Conclusion The automated approach successfully segmented and measured the brainstem and ventricular structures. DL-based models may represent a useful approach to support the diagnosis of PSP and potentially other conditions associated with brainstem and ventricular alterations. Keywords: MR Imaging, Brain/Brain Stem, Segmentation, Quantification, Diagnosis, Convolutional Neural Network Supplemental material is available for this article. © RSNA, 2024 See also the commentary by Mohajer in this issue.

Planimetric and Volumetric Brainstem MRI Markers in Progressive Supranuclear Palsy, Multiple System Atrophy, and Corticobasal Syndrome. A Systematic Review and Meta-Analysis

BACKGROUND

Various MRI markers-including midbrain and pons areas (Marea, Parea) and volumes (Mvol, Pvol), ratios (M/Parea, M/Pvol), and composite markers (magnetic resonance imaging Parkinsonism Indices 1,2; MRPI 1,2)-have been proposed as imaging markers of Richardson's syndrome (RS) and multiple system atrophy-Parkinsonism (MSA-P). A systematic review/meta-analysis of relevant studies aiming to compare the diagnostic accuracy of these imaging markers is lacking.

METHODS

Pubmed and Scopus were searched for studies with >10 patients (RS, MSA-P or CBS) and >10 controls with data on Marea, Parea, Mvol, Pvol, M/Parea, M/Pvol, MRPI 1, and MRPI 2. Cohen's d, as a measure of effect size, was calculated for all markers in RS, MSA-P, and CBS.

RESULTS

Twenty-five studies on RS, five studies on MSA-P, and four studies on CBS were included. Midbrain area provided the greatest effect size for differentiating RS from controls (Cohen's d = -3.10; p < 0.001), followed by M/Parea and MRPI 1. MSA-P had decreased midbrain and pontine areas. Included studies exhibited high heterogeneity, whereas publication bias was low.

CONCLUSIONS

Midbrain area is the optimal MRI marker for RS, and pons area is optimal for MSA-P. M/Parea and MRPIs produce smaller effect sizes for differentiating RS from controls.

Toward More Accessible Fully Automated 3D Volumetric MRI Decision Trees for the Differential Diagnosis of Multiple System Atrophy, Related Disorders, and Age-Matched Healthy Subjects

Differentiating multiple system atrophy (MSA) from related neurodegenerative movement disorders (NMD) is challenging. MRI is widely available and automated decision-tree analysis is simple, transparent, and resistant to overfitting. Using a retrospective cohort of heterogeneous clinical MRIs broadly sourced from a tertiary hospital system, we aimed to develop readily translatable and fully automated volumetric diagnostic decision-trees to facilitate early and accurate differential diagnosis of NMDs. 3DT1 MRI from 171 NMD patients (72 MSA, 49 PSP, 50 PD) and 171 matched healthy subjects were automatically segmented using Freesurfer6.0 with brainstem module. Decision trees employing substructure volumes and a novel volumetric pons-to-midbrain ratio (3D-PMR) were produced and tenfold cross-validation performed. The optimal tree separating NMD from healthy subjects selected cerebellar white matter, thalamus, putamen, striatum, and midbrain volumes as nodes. Its sensitivity was 84%, specificity 94%, accuracy 84%, and kappa 0.69 in cross-validation. The optimal tree restricted to NMD patients selected 3D-PMR, thalamus, superior cerebellar peduncle (SCP), midbrain, pons, and putamen as nodes. It yielded sensitivities/specificities of 94/84% for MSA, 72/96% for PSP, and 73/92% PD, with 79% accuracy and 0.62 kappa. There was correct classification of 16/17 MSA, 5/8 PSP, 6/8 PD autopsy-confirmed patients, and 6/8 MRIs that preceded motor symptom onset. Fully automated decision trees utilizing volumetric MRI data distinguished NMD patients from healthy subjects and MSA from other NMDs with promising accuracy, including autopsy-confirmed and pre-symptomatic subsets. Our open-source methodology is well-suited for widespread clinical translation. Assessment in even more heterogeneous retrospective and prospective cohorts is indicated.

Quantitative MRI protocol and decision model for a 'one stop shop' early-stage Parkinsonism diagnosis: Study design

Differentiating among early-stage parkinsonisms is a challenge in clinical practice. Quantitative MRI can aid the diagnostic process, but studies with singular MRI techniques have had limited success thus far. Our objective is to develop a multi-modal MRI method for this purpose. In this review we describe existing methods and present a dedicated quantitative MRI protocol, a decision model and a study design to validate our approach ahead of a pilot study. We present example imaging data from patients and a healthy control, which resemble related literature.

Clinical features of progressive supranuclear palsy

Background

Progressive supranuclear palsy (PSP) is a clinically heterogenous atypical parkinsonian syndrome. Therefore, early recognition and correct diagnosis of PSP is challenging but essential. This study aims to characterize the clinical manifestations, magnetic resonance imaging (MRI), and longitudinal MRI changes of PSP in China.

Method

Clinical and MRI presentations were compared among 150 cases with PSP. Then the longitudinal MRI changes among 20 patients with PSP were further explored. Additionally, a series of midbrain-based MRI parameters was compared between PSP-P and PD.

Results

Throughout the course of the disease, there were differences in the symptoms of the fall and hand tremor between the PSP-RS and PSP-P. There were significant differences in the six midbrain-based MRI parameters between the PSP-RS and the PSP-P, including hummingbird sign, midbrain diameter, midbrain to pons ratio (MTPR), midbrain area, midbrain area to pons area ratio (Ma/Pa), and midbrain tegmental length (MBTegm). Longitudinal MRI studies revealed that the annual rel.ΔMTPR and rel.Δ (Ma/Pa) for PSP were 5.55 and 6.52%, respectively; additionally, PSP-RS presented a higher decline rate than PSP-P. Moreover, MTPR ≤0.56, midbrain diameter ≤ 0.92, midbrain area ≤ 1.00, and third ventricle width ≤ 0.75 could identify PSP-P from PD.

Conclusion

PSP-P differs from PSP-RS regarding clinical manifestations, MRI, and longitudinal MRI changes. MRI parameters could be potential imaging markers to identify PSP-P from PD.

The Role of the Evans Index and the Maximal Width of the Frontal Horns of the Lateral Ventricles in the Diagnostic Imaging of Progressive Supranuclear Palsy and Multiple-System Atrophy

Progressive Supranuclear Palsy and Multiple-System Atrophy are entities within the spectrum of atypical parkinsonism. The role of imaging methods in the diagnosis and differentiation between PSP and MSA is limited and Magnetic Resonance Imaging (MRI) is currently used as a reference modality. In this study, the authors examined a group of patients with atypical parkinsonism using a 1.5 T MRI system and aimed to find simple and repeatable measurements that may be useful to distinguish between these diseases. The results of the study indicate that the maximal width of the frontal horns of the lateral ventricles and Evans' Index may, to some extent, be useful as basic and simple measurements in the diagnostic imaging of patients with atypical parkinsonism.

Magnetic resonance imaging in the diagnosis of progressive supranuclear palsy: A case report and review of literature

Key Clinical Message

Progressive supranuclear palsy (PSP) has many clinical features overlapping with other Parkinson syndromes and differentiation on clinical ground is difficult. This case highlights how a brain MRI can help diagnose PSP in settings with limited resources where histological diagnosis is difficult.

Abstract

Progressive supranuclear palsy (PSP) may be challenging to diagnose due to its widely acknowledged clinical complexity and challenges with diagnosis confirmation, particularly in resource-poor settings where the ability to obtain confirmatory tests is highly complicated, leading to an inaccurate or incomplete diagnosis of PSP. This paper discusses using brain magnetic resonance imaging (MRI) to diagnose PSP, and a review of relevant literature addresses the diagnostic value of MRI in PSP.

Clinicoradiologic and Neuropathologic Evaluation of Corticobasal Syndrome

BACKGROUND AND OBJECTIVES

Corticobasal syndrome (CBS) is a clinical phenotype characterized by asymmetric parkinsonism, rigidity, myoclonus, and apraxia. Originally believed secondary to corticobasal degeneration (CBD), mounting clinicopathologic studies have revealed heterogenous neuropathologies. The objectives of this study were to determine the pathologic heterogeneity of CBS, the clinicoradiologic findings associated with different underlying pathologies causing CBS, and the positive predictive value (PPV) of current diagnostic criteria for CBD among patients with a CBS.

METHODS

Clinical data, brain MRI, and neuropathologic data of patients followed at Mayo Clinic and diagnosed with CBS antemortem were reviewed according to neuropathology category at autopsy.

RESULTS

The cohort consisted of 113 patients with CBS, 61 (54%) female patients. Mean ± SD disease duration was 7 ± 3.7 years; mean ± SD age at death was 70.5 ± 9.1 years. The primary neuropathologic diagnoses were 43 (38%) CBD, 27 (24%) progressive supranuclear palsy (PSP), 17 (15%) Alzheimer disease (AD), 10 (9%) frontotemporal lobar degeneration (FTLD) with TAR DNA-binding protein 43 (TDP) inclusions, 7 (6%) diffuse Lewy body disease (DLBD)/AD, and 9 (8%) with other diagnoses. Patients with CBS-AD or CBS-DLBD/AD were youngest at death (median [interquartile range]: 64 [13], 64 [11] years) while CBS-PSP were oldest (77 [12.5] years, p = 0.024). Patients with CBS-DLBD/AD had the longest disease duration (9 [6] years), while CBS-other had the shortest (3 [4.25] years, p = 0.04). Posterior cortical signs and myoclonus were more characteristic of patients with CBS-AD and patients with CBS-DLBD/AD. Patients with CBS-DLBD/AD displayed more features of Lewy body dementia. Voxel-based morphometry revealed widespread cortical gray matter loss characteristic of CBS-AD, while CBS-CBD and CBS-PSP predominantly involved premotor regions with greater amount of white matter loss. Patients with CBS-DLBD/AD showed atrophy in a focal parieto-occipital region, and patients with CBS-FTLD-TDP had predominant prefrontal cortical loss. Patients with CBS-PSP had the lowest midbrain/pons ratio (p = 0.012). Of 67 cases meeting clinical criteria for possible CBD at presentation, 27 were pathology-proven CBD, yielding a PPV of 40%.

DISCUSSION

A variety of neurodegenerative disorders can be identified in patients with CBS, but clinical and regional imaging differences aid in predicting underlying neuropathology. PPV analysis of the current CBD diagnostic criteria revealed suboptimal performance. Biomarkers adequately sensitive and specific for CBD are needed.

The Role of Clinical Assessment in the Era of Biomarkers

Hippocratic Medicine revolved around the three main principles of patient, disease, and physician and promoted the systematic observation of patients, rational reasoning, and interpretation of collected information. Although these remain the cardinal features of clinical assessment today, Medicine has evolved from a more physician-centered to a more patient-centered approach. Clinical assessment allows physicians to encounter, observe, evaluate, and connect with patients. This establishes the patient-physician relationship and facilitates a better understanding of the patient-disease relationship, as the ultimate goal is to diagnose, prognosticate, and treat. Biomarkers are at the core of the more disease-centered approach that is currently revolutionizing Medicine as they provide insight into the underlying disease pathomechanisms and biological changes. Genetic, biochemical, radiographic, and clinical biomarkers are currently used. Here, we define a seven-level theoretical construct for the utility of biomarkers in neurodegenerative diseases. Level 1-3 biomarkers are considered supportive of clinical assessment, capable of detecting susceptibility or risk factors, non-specific neurodegeneration or dysfunction, and/or changes at the individual level which help increase clinical diagnostic accuracy and confidence. Level 4-7 biomarkers have the potential to surpass the utility of clinical assessment through detection of early disease stages and prediction of underlying pathology. In neurodegenerative diseases, biomarkers can potentiate, but cannot substitute, clinical assessment. In this current era, aside from adding to the discovery, evaluation/validation, and implementation of more biomarkers, clinical assessment remains crucial to maintaining the personal, humanistic, and sociocultural aspects of patient care. We would argue that clinical assessment is a custom that should never go obsolete.

Imaging Criteria for the Diagnosis of Progressive Supranuclear Palsy: Supportive or Mandatory?

We present the case of a 54-year-old male, without any significant medical history, who insidiously developed speech disturbances and walking difficulties, accompanied by backward falls. The symptoms progressively worsened over time. The patient was initially diagnosed with Parkinson's disease; however, he failed to respond to standard therapy with Levodopa. He came to our attention for worsening postural instability and binocular diplopia. A neurological exam was highly suggestive of a Parkinson-plus disease, most likely progressive supranuclear gaze palsy. Brain MRI was performed and revealed moderate midbrain atrophy with the characteristic "hummingbird" and "Mickey mouse" signs. An increased MR parkinsonism index was also noted. Based on all clinical and paraclinical data, a diagnosis of probable progressive supranuclear palsy was established. We review the main imaging features of this disease and their current role in diagnosis.

Superior cerebellar peduncle atrophy of progressive supranuclear palsy on phase difference enhanced imaging: a comparison with Parkinson's disease

PURPOSE

Phase difference enhanced (PADRE) imaging can enhance myelin density and delineate the superior cerebellar peduncle (SCP). We aimed to determine if SCP atrophy was distinguishable on PADRE imaging and evaluate its diagnostic performance compared with previous MRI progressive supranuclear palsy (PSP) findings.

METHODS

Two reviewers measured the SCP widths on PADRE in 20 PSP and 31 Parkinson's disease (PD) patients. The SCP and middle cerebellar peduncle (MCP) widths and the pons and midbrain areas were measured on 3D-T1WI, and the ratio of the area of the pons to the area of the midbrain, the MCP/SCP ratio, and the magnetic resonance parkinsonism index (MRPI) were calculated. We used the Steel-Dwass test to compare PSP, PD, and HS, and receiver operating characteristic curve (ROC) analyses to assess the sensitivity and specificity for diagnosing PSP from PD. A comparison of ROC curves was performed between the SCP on PADRE and these 3D-T1WI parameters.

RESULTS

In radiologist 1, the SCP on PADRE in PSP (1.1 ± 0.3 mm) was significantly smaller than those in PD (2.4 ± 0.4 mm) (P < 0.001); the area under the curve (AUC) was 0.97. At a 1.75-mm cutoff value, the diagnostic sensitivity and specificity for differentiating PSP from PD were 93.5% and 100%, respectively. The AUC of the SCP on PADRE was significantly higher than the 3D-T1WI parameters (the SCP, MCP, pons area, MCP/SCP ratio, and MRPI).

CONCLUSION

Assessing SCP with PADRE imaging may yield high diagnostic accuracy for discriminating PSP from PD.

Machine Learning for Brain MRI Data Harmonisation: A Systematic Review

BACKGROUND

Magnetic Resonance Imaging (MRI) data collected from multiple centres can be heterogeneous due to factors such as the scanner used and the site location. To reduce this heterogeneity, the data needs to be harmonised. In recent years, machine learning (ML) has been used to solve different types of problems related to MRI data, showing great promise.

OBJECTIVE

This study explores how well various ML algorithms perform in harmonising MRI data, both implicitly and explicitly, by summarising the findings in relevant peer-reviewed articles. Furthermore, it provides guidelines for the use of current methods and identifies potential future research directions.

METHOD

This review covers articles published through PubMed, Web of Science, and IEEE databases through June 2022. Data from studies were analysed based on the criteria of Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). Quality assessment questions were derived to assess the quality of the included publications.

RESULTS

a total of 41 articles published between 2015 and 2022 were identified and analysed. In the review, MRI data has been found to be harmonised either in an implicit (n = 21) or an explicit (n = 20) way. Three MRI modalities were identified: structural MRI (n = 28), diffusion MRI (n = 7) and functional MRI (n = 6).

CONCLUSION

Various ML techniques have been employed to harmonise different types of MRI data. There is currently a lack of consistent evaluation methods and metrics used across studies, and it is recommended that the issue be addressed in future studies. Harmonisation of MRI data using ML shows promises in improving performance for ML downstream tasks, while caution should be exercised when using ML-harmonised data for direct interpretation.

Brainstem atrophy in dementia with Lewy bodies compared with progressive supranuclear palsy and Parkinson's disease on MRI

BACKGROUND

Although Dementia with Lewy bodies (DLB) is the second most common form of dementia in elderly patients, it remains underdiagnosed compared with Alzheimer's (AD) and Parkinson's diseases (PD). This may be explained by overlapping clinical symptoms, e.g. Parkinsonism. While current MRI research focuses primarily on atrophy patterns of the frontal and temporal lobes, we focus on brainstem characteristics of DLB. In particular, we focused on brainstem atrophy patterns distinguishing DLB from Progressive Supranuclear Palsy (PSP) and PD based as the most common differential diagnoses.

METHODS

We identified patients diagnosed with DLB, PD, PSP, and a control group (CTRL) in our psychiatric and neurological archives. All patients with competing diagnoses and without a high-quality T1 MPRAGE 3D dataset were excluded. We assessed atrophy patterns in all patients (1) manually and (2) using FastSurfer's segmentation algorithm in combination with FreeSurfer's brainstem volumetric calculations. We compared classical measurement methods and ratios with automated volumetric approaches.

RESULTS

One hundred two patients were enrolled and evaluated in this study. Patients with DLB (n = 37) showed on average less atrophy of the brainstem than patients with PSP (n = 21), but a significantly more pronounced atrophy than patients with PD (n = 36) and the control group (CTRL, n = 8). The mean measured sagittal diameters of the midbrain were 8.17 ± 1.06 mm (mean ± standard deviation) for PSP, 9.45 ± 0.95 mm for DLB, 10.37 ± 0.99 mm for PD and 10.74 ± 0.70 for CTRL. The mean measured areas of the midbrain were 81 ± 18 mm² for PSP, 105 ± 17 mm² for DLB, 130 ± 26 mm² for PD and 135 ± 23 mm² for CTRL. The mean segmented volumes of the midbrain were 5595 ± 680 mm³ for PSP, 6051 ± 566 mm³ for DLB, 6646 ± 802 mm³ for PD and 6882 ± 844 mm³ for CTRL. The calculated midbrain pons ratios did not show superiority over the absolute measurements of the midbrain for distinguishing PSP from DLB. Because of the relatively uniform atrophy throughout the brainstem, the ratios were not suitable for distinguishing DLB from PD.

CONCLUSIONS

DLB patients exhibit homogenous atrophy of the brainstem and can be distinguished from patients with PSP and PD by both manual measurement methods and automated volume segmentation using absolute values or ratios.

Comparative validation of AI and non-AI methods in MRI volumetry to diagnose Parkinsonian syndromes

Automated segmentation and volumetry of brain magnetic resonance imaging (MRI) scans are essential for the diagnosis of Parkinson's disease (PD) and Parkinson's plus syndromes (P-plus). To enhance the diagnostic performance, we adopt deep learning (DL) models in brain MRI segmentation and compared their performance with the gold-standard non-DL method. We collected brain MRI scans of healthy controls ([Formula: see text]) and patients with PD ([Formula: see text]), multiple systemic atrophy ([Formula: see text]), and progressive supranuclear palsy ([Formula: see text]) at Samsung Medical Center from January 2017 to December 2020. Using the gold-standard non-DL model, FreeSurfer (FS), we segmented six brain structures: midbrain, pons, caudate, putamen, pallidum, and third ventricle, and considered them as annotated data for DL models, the representative convolutional neural network (CNN) and vision transformer (ViT)-based models. Dice scores and the area under the curve (AUC) for differentiating normal, PD, and P-plus cases were calculated to determine the measure to which FS performance can be reproduced as-is while increasing speed by the DL approaches. The segmentation times of CNN and ViT for the six brain structures per patient were 51.26 ± 2.50 and 1101.82 ± 22.31 s, respectively, being 14 to 300 times faster than FS (15,735 ± 1.07 s). Dice scores of both DL models were sufficiently high (> 0.85) so their AUCs for disease classification were not inferior to that of FS. For classification of normal vs. P-plus and PD vs. P-plus (except multiple systemic atrophy - Parkinsonian type) based on all brain parts, the DL models and FS showed AUCs above 0.8, demonstrating the clinical value of DL models in addition to FS. DL significantly reduces the analysis time without compromising the performance of brain segmentation and differential diagnosis. Our findings may contribute to the adoption of DL brain MRI segmentation in clinical settings and advance brain research.

Magnetic resonance imaging modalities aid in the differential diagnosis of atypical parkinsonian syndromes

Accurate and timely diagnosis of atypical parkinsonian syndromes (APS) remains a challenge. Especially early in the disease course, the clinical manifestations of the APS overlap with each other and with those of idiopathic Parkinson's disease (PD). Recent advances in magnetic resonance imaging (MRI) technology have introduced promising imaging modalities to aid in the diagnosis of APS. Some of these MRI modalities are also included in the updated diagnostic criteria of APS. Importantly, MRI is safe for repeated use and more affordable and accessible compared to nuclear imaging. These advantages make MRI tools more appealing for diagnostic purposes. As the MRI field continues to advance, the diagnostic use of these techniques in APS, alone or in combination, are expected to become commonplace in clinical practice.

Multiclass prediction of different dementia syndromes based on multi-centric volumetric MRI imaging

INTRODUCTION

Dementia syndromes can be difficult to diagnose. We aimed at building a classifier for multiple dementia syndromes using magnetic resonance imaging (MRI).

METHODS

Atlas-based volumetry was performed on T1-weighted MRI data of 426 patients and 51 controls from the multi-centric German Research Consortium of Frontotemporal Lobar Degeneration including patients with behavioral variant frontotemporal dementia, Alzheimer's disease, the three subtypes of primary progressive aphasia, i.e., semantic, logopenic and nonfluent-agrammatic variant, and the atypical parkinsonian syndromes progressive supranuclear palsy and corticobasal syndrome. Support vector machine classification was used to classify each patient group against controls (binary classification) and all seven diagnostic groups against each other in a multi-syndrome classifier (multiclass classification).

RESULTS

The binary classification models reached high prediction accuracies between 71 and 95% with a chance level of 50%. Feature importance reflected disease-specific atrophy patterns. The multi-syndrome model reached accuracies of more than three times higher than chance level but was far from 100%. Multi-syndrome model performance was not homogenous across dementia syndromes, with better performance in syndromes characterized by regionally specific atrophy patterns. Whereas diseases generally could be classified vs controls more correctly with increasing severity and duration, differentiation between diseases was optimal in disease-specific windows of severity and duration.

DISCUSSION

Results suggest that automated methods applied to MR imaging data can support physicians in diagnosis of dementia syndromes. It is particularly relevant for orphan diseases beside frequent syndromes such as Alzheimer's disease.

Visual fixation suppression of caloric nystagmus in progressive supranuclear palsy - A comparison with Parkinson's disease

BACKGROUND

Impairment of visual fixation suppression (VS) in progressive supranuclear palsy (PSP) is not well documented.

OBJECTIVE

To evaluate the usefulness of impaired VS of caloric nystagmus as an index for differential diagnosis between PSP and Parkinson's disease (PD), which is often difficult, especially in the early stage.

METHODS

Subjects comprised 26 PSP patients and 26 PD patients clinically diagnosed at Tokyo Metropolitan Neurological Hospital. We retrospectively investigated VS of caloric nystagmus, horizontal pursuit, saccades, and horizontal optokinetic nystagmus recorded on direct-current-electronystagmography, and neuroradiological findings.

RESULTS

The median of the average VS% was 0% and 50.0% in PSP and PD patients, respectively. In PSP, VS was impaired even in the early stage of disease. We found a significant correlation between VS and velocity of saccades or maximum slow phase velocity of optokinetic nystagmus only in PSP patients. PSP patients with atrophy of the subthalamic nucleus or with decreased blood flow in the frontal lobe showed significantly more severe impairment of VS.

CONCLUSIONS

VS may be a useful biomarker to differentiate patients with PSP from those with PD. Cerebellar networks that connect with the cerebral cortex and basal ganglia may contribute to impaired VS of caloric nystagmus in PSP.

C. P. The role of width of pars compacta of substantia nigra and the midbrain area in patients with Parkinson’s disease and progressive supranuclear palsy with healthy aged individuals

Introduction and Aim: Though numerous image processing software exists to analyse the images, measurement of substantia nigra width and midbrain area are simple yet definite tools to distinguish and diagnose the Parkinson’s disease (PD) and progressive supranuclear palsy (PSP) when complimented with clinical findings. Comparing the brainstem parameters in healthy, (neurodegenerative) diseased, and during the treatment helps us to assess the disease monitoring i.e., severity and progress of the disease, and formulate the best treatment strategies.  This study aimed at comparison of the thickness of substantia nigra (SN) in Parkinson's disease (PD) and progressive supranuclear palsy (PSP) with aged healthy individuals by magnetic resonance (MR) imaging. Material and Methods: This observational study includes the evaluation of MR images of 50 aged healthy individuals with no obvious neurological diseases, 35 classical PD, and 15 PSP patients from the Department of Radiology. Quantitative planimetric evaluation of midbrain area was calculated and the width of substantia nigra (SN) was evaluated as per standard reference criteria with computer assisted image analysis and interpretation program. Results: The parameters like means of midbrain area and the pars compacta thickness on both right and left sides were compared both in PD and PSP patients with healthy individuals. MR image analysis showed significant decrease in the thickness of pars compacta of SN in PD patients than in PSP patients when compared with age matched healthy aged individuals. Conclusion: Parkinsonian diseases are always associated with the neuronal loss leading to volume alterations by causing midbrain atrophy. Magnetic resonance imaging of the thickness of SN is simple and reliable imaging markers to differentiate PD and PSP when combined with clinical symptomatology.

Magnetic Resonance Planimetry in the Differential Diagnosis between Parkinson’s Disease and Progressive Supranuclear Palsy

The clinical differential diagnosis between Parkinson’s disease (PD) and progressive supranuclear palsy (PSP) is often challenging. The description of milder PSP phenotypes strongly resembling PD, such as PSP-Parkinsonism, further increased the diagnostic challenge and the need for reliable neuroimaging biomarkers to enhance the diagnostic certainty. This review aims to summarize the contribution of a relatively simple and widely available imaging technique such as MR planimetry in the differential diagnosis between PD and PSP, focusing on the recent advancements in this field. The development of accurate MR planimetric biomarkers, together with the implementation of automated algorithms, led to robust and objective measures for the differential diagnosis of PSP and PD at the individual level. Evidence from longitudinal studies also suggests a role of MR planimetry in predicting the development of the PSP clinical signs, allowing to identify PSP patients before they meet diagnostic criteria when their clinical phenotype can be indistinguishable from PD. Finally, promising evidence exists on the possible association between MR planimetric measures and the underlying pathology, with important implications for trials with new disease-modifying target therapies.

Lateralization of the crossed cerebellar diaschisis-associated metabolic connectivities in cortico-ponto-cerebellar and cortico-rubral pathways

This study aimed to explore the glucose metabolic profile of extrapyramidal system in patients with crossed cerebellar diaschisis (CCD). Furthermore, the metabolic connectivities in cortico-ponto-cerebellar and cortico-rubral pathways associated with CCD were also investigated. A total of 130 CCD positive (CCD+) and 424 CCD negative (CCD-) patients with unilateral cerebral hemisphere hypometabolism on ¹⁸F-fluorodeoxyglucose positron emission tomography (¹⁸F-FDG PET) were enrolled. Besides, the control group consisted of 56 subjects without any brain structural and metabolic abnormalities. Apart from the "autocorrelation", metabolic connectivity pattern of right or left affected cerebellar hemisphere involved unilateral (left or right, respectively) caudate, pallidum, putamen, thalamus and red nucleus, in CCD+ patients with left or right supratentorial lesions, respectively (P_uncorrected < 0.001, cluster size > 200). CCD+ group had significantly lower asymmetry index (AI) in cortico-ponto-cerebellar pathway (including ipsilateral cerebral white matter, ipsilateral pons, contralateral cerebellum white matter and contralateral cerebellum exterior cortex) and cortico-rubral pathway (including ipsilateral caudate, thalamus proper, pallidum, putamen, ventral diencephalon and red nucleus) than those of both CCD- and control groups (all P < 0.05). AI in contralateral cerebellum exterior cortex was significantly positively correlated with that in ipsilateral caudate, putamen, pallidum, thalamus proper, ventral diencephalon, red nucleus and pons among CCD+ group (all P < 0.01), but only with that in ipsilateral caudate and putamen among CCD- group (both P < 0.001). These results provide additional insight into the involvement of both cortico-ponto-cerebellar and cortico-rubral pathways in the presence of CCD, underlining the need for further investigation about the role of their aberrant metabolic connectivities in the associated symptoms of CCD.

Morphometric imaging and quantitative susceptibility mapping as complementary tools in the diagnosis of parkinsonisms

Background and purpose

In the quest for in vivo diagnostic biomarkers to discriminate Parkinson's disease (PD) from progressive supranuclear palsy (PSP) and multiple system atrophy (MSA, mainly p phenotype), many advanced magnetic resonance imaging (MRI) techniques have been studied. Morphometric indices, such as the Magnetic Resonance Parkinsonism Index (MRPI), demonstrated high diagnostic value in the comparison between PD and PSP. The potential of quantitative susceptibility mapping (QSM) was hypothesized, as increased magnetic susceptibility (Δχ) was reported in the red nucleus (RN) and medial part of the substantia nigra (SNImed) of PSP patients and in the putamen of MSA patients. However, disease‐specific susceptibility values for relevant regions of interest are yet to be identified. The aims of the study were to evaluate the diagnostic potential of a multimodal MRI protocol combining morphometric and QSM imaging in patients with determined parkinsonisms and to explore its value in a population of undetermined cases.

Method

Patients with suspected degenerative parkinsonism underwent clinical evaluation, 3 T brain MRI and clinical follow‐up. The MRPI was manually calculated on T1‐weighted images. QSM maps were generated from 3D multi‐echo T2*‐weighted sequences.

Results

In determined cases the morphometric evaluation confirmed optimal diagnostic accuracy in the comparison between PD and PSP but failed to discriminate PD from MSA‐p. Significant nigral and extranigral differences were found with QSM. RN Δχ showed excellent diagnostic accuracy in the comparison between PD and PSP and good accuracy in the comparison of PD and MSA‐p. Optimal susceptibility cut‐off values of RN and SNImed were tested in undetermined cases in addition to MRPI.

Conclusions

A combined use of morphometric imaging and QSM could improve the diagnostic phase of degenerative parkinsonisms.

Normative Data for Brainstem Structures, the Midbrain-to-Pons Ratio, and the Magnetic Resonance Parkinsonism Index

BACKGROUND AND PURPOSE

Imaging biomarkers derived from different brainstem structures are suggested to differentiate among parkinsonian disorders, but clinical implementation requires normative data. The main objective was to establish high-quality, sex-specific data for relevant brainstem structures derived from MR imaging in healthy subjects from the general population in their sixth and seventh decades of life.

MATERIALS AND METHODS

3D T1WI acquired on the same 1.5T scanner of 996 individuals (527 women) between 50 and 66 years of age from a prospective population study was used. The area of the midbrain and pons and the widths of the middle cerebellar peduncles and superior cerebellar peduncles were measured, from which the midbrain-to-pons ratio and Magnetic Resonance Parkinsonism Index [MRPI = (Pons Area / Midbrain Area) × (Middle Cerebellar Peduncles / Superior Cerebellar Peduncles)] were calculated. Sex differences in brainstem measures and correlations to age, height, weight, and body mass index were investigated.

RESULTS

Inter- and intrareliability for measuring the different brainstem structures showed good-to-excellent reliability (intraclass correlation coefficient = 0.785-0.988). There were significant sex differences for the pons area, width of the middle cerebellar peduncles and superior cerebellar peduncles, midbrain-to-pons ratio, and MRPI (all, P <  .001; Cohen D = 0.44-0.98), but not for the midbrain area (P = .985). There were significant very weak-to-weak correlations between several of the brainstem measures and age, height, weight, and body mass index in both sexes. However, no systematic difference in distribution caused by these variables was found, and because age had the highest and most consistent correlations, age-/sex-specific percentiles for the brainstem measures were created.

CONCLUSIONS

We present high-quality, sex-specific data and age-/sex-specific percentiles for the mentioned brainstem measures. These normative data can be implemented in the neuroradiologic work-up of patients with suspected brainstem atrophy to avoid the risk of misdiagnosis.

The Distance Between the Cranial Nerve IX-X Root Entry/Exit Zone and the Pontomedullary Sulcus: MR Imaging Study in Patients With Hemifacial Spasm

Subject

To quantitatively describe the distance between the cranial nerve (CN) IX-X root entry/exit zone (REZ) and the pontomedullary sulcus in patients with hemifacial spasm (HFS).

Methods

A total of 215 outpatients with HFS were recruited. Finally, 108 patients who yielded high-quality images were enrolled in the study. MRIs were reconstructed to measure the distance between the bilateral CN IX-X REZs and the corresponding pontomedullary sulcus.

Results

Among the 108 patients, the ratio of males to females was 39/69, and the mean age was 57.9 ± 6.5 years. The ratio of left to right HFS involvement was 47/61. The average height was 1.62 ± 0.07 m, and the average body mass index (BMI) was 24.65 ± 2.97 kg/m². The distance between the cephalic end of the CN IX-X REZ and the pontomedullary sulcus was 2.7 ± 0.9 mm. The distance between the caudal end of the CN IX-X REZ and the pontomedullary sulcus was 7.6 ± 1.1 mm. No monotonic relationship was found between distance and height or BMI in the scatter diagrams.

Conclusions

The CN IX-X REZ is closely related to the pontomedullary sulcus in patients with HFS, and there is no difference between the left and right sides. The distances were not correlated with height or BMI in patients with HFS.

Neuroimaging Pearls from the MDS Congress Video Challenge. Part 2: Acquired Disorders

The MDS Video Challenge continues to be the one of most widely attended sessions at the International Congress. Although the primary focus of this event is the presentation of complex and challenging cases through videos, a number of cases over the years have also presented an unusual or important neuroimaging finding related to the case. We reviewed the previous Video Challenge cases and present here a selection of those cases which incorporated such imaging findings. We have compiled these "imaging pearls" into two anthologies. The first focuses on pearls where the underlying diagnosis was a genetic condition. This second anthology focuses on imaging pearls in cases where the underlying condition was acquired. For each case we present brief clinical details along with neuroimaging findings, the characteristic imaging findings of that disorder and, finally, the differential diagnosis for the imaging findings seen.

The Strengths and Obstacles in the Differential Diagnosis of Progressive Supranuclear Palsy—Parkinsonism Predominant (PSP-P) and Multiple System Atrophy (MSA) Using Magnetic Resonance Imaging (MRI) and Perfusion Single Photon Emission Computed Tomography (SPECT)

Multiple System Atrophy—Parkinsonism Predominant (MSA-P) and Progressive Supranuclear Palsy—Parkinsonism Predominant (PSP-P) are the clinical manifestations of atypical parkinsonism. Currently, there are no efficient in vivo methods available relating to neuroimaging or biochemical analysis in the examination of these entities. Among the advanced methods available, using positron emission tomography is constrained by high cost and low accessibility. In this study the authors examined patients with two types of atypical parkinsonism—MSA-P and PSP-P, which are difficult to differentiate, especially in the early years of their development. The aim of this study was to assess whether the examination of patients in the period following the early years (3–6-year duration of symptoms) could be enhanced by perfusion single photon emission computed tomography (SPECT), magnetic resonance imaging (MRI) or evaluation of cognitive abilities. Extended examination using MRI and perfusion SPECT showed that the evaluation of the mesencephalon/pons ratio, mesencephalic volume decrease, the Magnetic Resonance Parkinsonism Index (MRPI) and frontal perfusion should be considered more feasible than screening cognitive evaluation in MSA-P and PSP-P with a 3–6-year duration of symptoms.

Brainstem Biomarkers of Clinical Variant and Pathology in Progressive Supranuclear Palsy

BACKGROUND

Magnetic resonance brainstem measurements are useful structural biomarkers in the Richardson's syndrome variant of progressive supranuclear palsy (PSP). However, it is unclear how these biomarkers differ across the phenotypic spectrum of PSP and how they relate to underlying pathology.

OBJECTIVE

The aim of this study was to compare brainstem imaging measures across clinical variants of PSP and determine sensitivity and specificity based on pathologically diagnosed cases.

METHODS

A total of 153 patients with PSP who represented eight clinical variants were recruited at Mayo Clinic (Rochester, MN, USA) and underwent structural magnetic resonance imaging (MRI). Midbrain and pons area and superior and middle cerebellar peduncle width measurements were performed, and midbrain/pons ratio and Magnetic Resonance Parkinsonism Index (MRPI) were calculated. Among the 43 patients who later died, PSP pathology was confirmed in 29, whereas 14 had other pathology.

RESULTS

Brainstem measurements varied across PSP clinical variants and were most abnormal in PSP-Richardson's syndrome and frontal variants, followed by PSP-corticobasal, PSP-speech/language, and PSP-parkinsonism variants. All these variants showed abnormalities compared with controls. The PSP-gait freezing variant and patients with prominent corticospinal tract signs showed normal brainstem measures. Among cases with confirmed PSP pathology, the midbrain area, midbrain/pons ratio, and MRPI were all more abnormal compared to those with other pathologies, with best differentiation obtained with the MRPI (sensitivity = 83%; specificity = 85%).

CONCLUSIONS

MRI brainstem measures show utility as diagnostic biomarkers across PSP clinical variants and have the potential to be useful in predicting underlying pathology. © 2021 International Parkinson and Movement Disorder Society.

Agreement Between Automated and Manual MRI Volumetry in Alzheimer's Disease: A Systematic Review and Meta-Analysis

BACKGROUND

Automated magnetic resonance imaging (MRI) volumetry is a promising tool to evaluate regional brain volumes in dementia and especially Alzheimer's disease (AD).

PURPOSE

To compare automated methods and the gold standard manual segmentation in measuring regional brain volumes on MRI across healthy controls, patients with mild cognitive impairment, and patients with dementia due to AD.

STUDY TYPE

Systematic review and meta-analysis.

DATA SOURCES

MEDLINE, Embase, and PsycINFO were searched through October 2021.

FIELD STRENGTH

1.0 T, 1.5 T, or 3.0 T.

ASSESSMENT

Two review authors independently identified studies for inclusion and extracted data. Methodological quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2).

STATISTICAL TESTS

Standardized mean differences (SMD; Hedges' g) were pooled using random-effects meta-analysis with robust variance estimation. Subgroup analyses were undertaken to explore potential sources of heterogeneity. Sensitivity analyses were conducted to examine the impact of the within-study correlation between effect estimates on the meta-analysis results.

RESULTS

Seventeen studies provided sufficient data to evaluate the hippocampus, lateral ventricles, and parahippocampal gyrus. The pooled SMD for the hippocampus, lateral ventricles, and parahippocampal gyrus were 0.22 (95% CI -0.50 to 0.93), 0.12 (95% CI -0.13 to 0.37), and -0.48 (95% CI -1.37 to 0.41), respectively. For the hippocampal data, subgroup analyses suggested that the pooled SMD was invariant across clinical diagnosis and field strength. Subgroup analyses could not be conducted on the lateral ventricles data and the parahippocampal gyrus data due to insufficient data. The results were robust to the selected within-study correlation value.

DATA CONCLUSION

While automated methods are generally comparable to manual segmentation for measuring hippocampal, lateral ventricle, and parahippocampal gyrus volumes, wide 95% CIs and large heterogeneity suggest that there is substantial uncontrolled variance. Thus, automated methods may be used to measure these regions in patients with AD but should be used with caution.

EVIDENCE LEVEL

3 TECHNICAL EFFICACY: Stage 3.

Diagnostic Performance of the Magnetic Resonance Parkinsonism Index in Differentiating Progressive Supranuclear Palsy from Parkinson's Disease: An Updated Systematic Review and Meta-Analysis

Progressive supranuclear palsy (PSP) and Parkinson's disease (PD) are difficult to differentiate especially in the early stages. We aimed to investigate the diagnostic performance of the magnetic resonance parkinsonism index (MRPI) in differentiating PSP from PD. A systematic literature search of PubMed-MEDLINE and EMBASE was performed to identify original articles evaluating the diagnostic performance of the MRPI in differentiating PSP from PD published up to 20 February 2021. The pooled sensitivity, specificity, and 95% CI were calculated using the bivariate random-effects model. The area under the curve (AUC) was calculated using a hierarchical summary receiver operating characteristic (HSROC) model. Meta-regression was performed to explain the effects of heterogeneity. A total of 14 original articles involving 484 PSP patients and 1243 PD patients were included. In all studies, T1-weighted images were used to calculate the MRPI. Among the 14 studies, nine studies used 3D T1-weighted images. The pooled sensitivity and specificity for the diagnostic performance of the MRPI in differentiating PSP from PD were 96% (95% CI, 87-99%) and 98% (95% CI, 91-100%), respectively. The area under the HSROC curve was 0.99 (95% CI, 0.98-1.00). Heterogeneity was present (sensitivity: I² = 97.29%; specificity: I² = 98.82%). Meta-regression showed the association of the magnet field strength with heterogeneity. Studies using 3 T MRI showed significantly higher sensitivity (100%) and specificity (100%) than those of studies using 1.5 T MRI (sensitivity of 98% and specificity of 97%) (p < 0.01). Thus, the MRPI could accurately differentiate PSP from PD and support the implementation of appropriate management strategies for patients with PSP.

Pontocerebellar atrophy is the hallmark neuroradiological finding in late-onset Tay-Sachs disease

PURPOSE

Late-onset Tay-Sachs disease (LOTS) is a form of GM2 gangliosidosis, an autosomal recessive neurodegenerative disorder characterized by slowly progressive cerebellar ataxia, lower motor neuron disease, and psychiatric impairment due to mutations in the HEXA gene. The aim of our work was to identify the characteristic brain MRI findings in this presumably underdiagnosed disease.

METHODS

Clinical data and MRI findings from 16 patients (10F/6 M) with LOTS from two centers were independently assessed by two readers and compared to 16 age- and sex-related controls.

RESULTS

Lower motor neuron disease (94%), psychiatric symptoms-psychosis (31%), cognitive impairment (38%) and depression (25%)-and symptoms of cerebellar impairment including dysarthria (94%), ataxia (81%) and tremor (69%), were the most common clinical features. On MRI, pontocerebellar atrophy was a constant finding. Compared to controls, LOTS patients had smaller mean middle cerebellar peduncle diameter (p < 0.0001), mean superior cerebellar peduncle diameter (p = 0.0002), mesencephalon sagittal area (p = 0.0002), pons sagittal area (p < 0.0001), and larger 4^th ventricle transversal diameter (p < 0.0001). Mild corpus callosum thinning (37.5%), mild cortical atrophy (18.8%), and white matter T2 hyperintensities (12.5%) were also present.

CONCLUSION

Given the characteristic clinical course and MRI findings of the pontocerebellar atrophy, late-onset Tay-Sachs disease should be considered in the differential diagnosis of adult-onset cerebellar ataxias.

Systematic Analysis of Brain MRI Findings in Adaptor Protein Complex 4-Associated Hereditary Spastic Paraplegia

BACKGROUND AND OBJECTIVES

AP-4-associated hereditary spastic paraplegia (AP-4-HSP: SPG47, SPG50, SPG51, SPG52) is an emerging cause of childhood-onset hereditary spastic paraplegia and mimic of cerebral palsy. This study aims to define the spectrum of brain MRI findings in AP-4-HSP and to investigate radioclinical correlations.

METHODS

We performed a systematic qualitative and quantitative analysis of 107 brain MRI studies from 76 individuals with genetically confirmed AP-4-HSP and correlation with clinical findings including surrogates of disease severity.

RESULTS

We define AP-4-HSP as a disorder of gray and white matter and demonstrate that abnormal myelination is common and that metrics of reduced white matter volume correlate with severity of motor symptoms. We identify a common diagnostic imaging signature consisting of (1) a thin splenium of the corpus callosum, (2) an absent or thin anterior commissure, (3) characteristic signal abnormalities of the forceps minor ("ears of the grizzly sign"), and (4) periventricular white matter abnormalities. The presence of 2 or more of these findings has a sensitivity of ∼99% for detecting AP-4-HSP; the combination of all 4 is found in ∼45% of cases. Compared to other HSPs with a thin corpus callosum, the absent anterior commissure appears to be specific to AP-4-HSP. Our analysis identified a subset of patients with polymicrogyria, underscoring the role of AP-4 in early brain development. These patients displayed a higher prevalence of seizures and status epilepticus, many at a young age.

DISCUSSION

Our findings define the MRI spectrum of AP-4-HSP, providing opportunities for early diagnosis, identification of individuals at risk for complications, and a window into the role of the AP-4 complex in brain development and neurodegeneration.

A Review of Neuroimaging in Rare Neurodegenerative Diseases

PURPOSE

Due to the variety of clinical symptoms that occur in rare neurodegenerative diseases and difficulties in the correct diagnosis, there is a need to learn their characteristic imaging findings by using conventional MRI. That knowledge helps to determine the appropriate differential diagnosis and avoid misdiagnosis. The aim of this review is to present the typical neuroimaging signs of the selected neurodegenerative disorders and to create a practical approach to imaging findings useful in everyday clinical practice. Images: Images of progressive supranuclear palsy (PSP), multiple system atrophy (MSA), corticobasal degeneration (CBD), Creutzfeldt-Jakob disease (CJD), Wilson's disease (WD), and cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) are provided to visualize and distinguish the typical features of those diseases and therefore to assist neurologists and neuroradiologists in decision-making process.

CONCLUSIONS

It is important to know the characteristic MRI features of rare neurodegenerative diseases and to use them in everyday clinical practice. MRI is a valuable tool when considering the initial diagnosis because it is proven to be very useful in the differentiation of more advanced stages of the rare neurodegenerative diseases but also from other neurodegenerative disorders.

Midbrain area and the hummingbird sign from brain MRI in progressive supranuclear palsy and idiopathic normal pressure hydrocephalus

BACKGROUND AND PURPOSE

The main radiological finding in progressive supranuclear palsy (PSP) is reduced midbrain volume. Both qualitative (e.g., hummingbird sign) and quantitative (e.g., area measurements) markers have been noted. Recent studies have shown a similar reduction also in idiopathic normal pressure hydrocephalus (iNPH). The purpose was to investigate the reliability and accuracy of these markers in discriminating PSP from iNPH and controls.

METHODS

Eight neuroradiologists viewed sagittal MR images of the midbrain from 104 subjects: 26 PSP patients, 40 iNPH patients, and 38 healthy controls. They visually assessed whether the hummingbird sign was present or not, grading their confidence from 1 to 5. Assessments were translated into a score between +5 and -5: from maximum confidence of presence to maximum confidence of absence. A positive median score was considered to indicate hummingbird sign. Sagittal midbrain area was manually measured in each subject.

RESULTS

Seventy-seven percent of PSP patients, 65% of iNPH, and 3% of controls were visually assessed as having the hummingbird sign. Manually measured midbrain area also showed overlap between PSP and iNPH. Regarding discrimination of PSP patients, midbrain area measurements, using a cutoff of 90 mm² , yielded a higher area under the curve (AUC = 0.86) than visual assessment scores (AUC = 0.83), and higher reliability.

CONCLUSIONS

Measuring sagittal midbrain area is more accurate and reliable than visual assessment. Due to significant overlap in appearance, a midbrain with a hummingbird sign or reduced sagittal area should raise the suspicion of PSP only after other signs of iNPH have been considered.

Caregiver strain in progressive supranuclear palsy and corticobasal syndromes

Progressive supranuclear palsy (PSP) and corticobasal syndrome (CBS) progress relentlessly and lead to a need for care. Caregiving is often burdensome. Little is known about the course of caregiver burden (CB) in PSP and CBS patients. Longitudinal analysis of CB in family members caring for PSP and CBS patients. Single-center longitudinal pilot study in 68 newly diagnosed patients with probable PSP and CBS (52 Richardson’s syndrome; 1 progressive gait freezing of PSP; 15 CBS). Demographic, educational, occupational parameters, family status, motor functions (UPDRSIII, Hoehn and Yahr Score, Tinetti) and neuropsychological performance (CERAD Plus, Frontal Assessment Battery) were assessed, as well as behavioral and neuropsychiatric impairments (Frontal Behavioral Inventory, Neuropsychiatric Inventory), activities of daily living (ADL) and caregiver burden using the Caregiver Strain Index (CSI), in most patients also the Zarit Burden Interview (ZBI). Patients were followed up every 6 months for up to 2 years. Caregivers reported mild to moderate CB at baseline, which increased by 25–30% in 2 years and was significantly greater in PSP than in CBS. Risk for mental health problems increased over time, especially in female caregivers (depression). Important patient-related factors were apathy, aspontaneity, depression, irritability, disorganization, poor judgment, impairment of language, impairments in ADL, a high educational level of the patient and close family relationship. Behavioral symptoms and impaired ADL are the main patient-related factors of CB in PSP and CBS. CB can be severe and needs to be assessed repeatedly from the time of diagnosis to provide comprehensive support.

Differentiating PSP from MSA using MR planimetric measurements: a systematic review and meta-analysis

Differential diagnosis of parkinsonian syndromes is considered one of the most challenging in neurology. Quantitative MR planimetric measurements were reported to discriminate between progressive supranuclear palsy (PSP) and non-PSP-parkinsonism. Several studies have used midbrain to pons ratio (M/P) and the Magnetic Resonance Parkinsonism Index (MRPI) in distinguishing PSP patients from those with Parkinson's disease. The current meta-analysis aimed to compare the performance of these measures in discriminating PSP from multiple system atrophy (MSA). A systematic MEDLINE review identified 59 out of 2984 studies allowing a calculation of sensitivity and specificity using the MRPI or M/P. Meta-analyses of results were carried out using random effects modelling. To assess study quality and risk of bias, the QUADAS-2 tool was used. Eight studies were suitable for analysis. The meta-analysis showed a pooled sensitivity and specificity for the MRPI of PSP versus MSA of 79.2% (95% CI 72.7-84.4%) and 91.2% (95% CI 79.5-96.5%), and 84.1% (95% CI 77.2-89.2%) and 89.2% (95% CI 81.8-93.8%), respectively, for the M/P. The QUADAS-2 toolbox revealed a high risk of bias regarding the methodological quality of patient selection and index test, as all patients were seen in a specialized outpatient department without avoiding case control design and no predefined threshold was given regarding MRPI or M/P cut-offs. Planimetric brainstem measurements, in special the MRPI and M/P, yield high diagnostic accuracy for the discrimination of PSP from MSA. However, there is an urgent need for well-designed, prospective validation studies to ameliorate the concerns regarding the risk of bias.

Update on neuroimaging for categorization of Parkinson's disease and atypical parkinsonism

PURPOSE OF REVIEW

Differential diagnosis of Parkinsonism may be difficult. The objective of this review is to present the work of the last three years in the field of imaging for diagnostic categorization of parkinsonian syndromes focusing on progressive supranuclear palsy (PSP) and multiple system atrophy (MSA).

RECENT FINDINGS

Two main complementary approaches are being pursued. The first seeks to develop and validate manual qualitative or semi-quantitative imaging markers that can be easily used in clinical practice. The second is based on quantitative measurements of magnetic resonance imaging abnormalities integrated in a multimodal approach and in automatic categorization machine learning tools.

SUMMARY

These two complementary approaches obtained high diagnostic around 90% and above in the classical Richardson form of PSP and probable MSA. Future work will determine if these techniques can improve diagnosis in other PSP variants and early forms of the diseases when all clinical criteria are not fully met.

Neuromelanin-sensitive magnetic resonance imaging in disease differentiation for parkinsonism or neurodegenerative disease affecting the basal ganglia

INTRODUCTION

Several reports have shown that neuromelanin-sensitive magnetic resonance imaging (NMI) using 3T magnetic resonance imaging is useful for the differential diagnosis of Parkinson's disease (PD), progressive supranuclear palsy (PSP), and other neurological diseases. However, the number of cases in previous studies has been insufficient. We aimed to determine the relationship between NMI and severity of PD and related disorders, and thereby establish the diagnostic utility of NMI for diagnosing neurological diseases.

METHODS

We enrolled 591 patients (531 subjects after removal of duplicates) with parkinsonism who underwent NMI. The contrast ratio of the locus coeruleus (LC-CR) and the area of the substantia nigra pars compacta (SNc) were analyzed in each patient.

RESULTS

The patients' clinical diagnoses were as follows: 11 patients in the disease control group (DCG), 244 patients with PD, 49 patients with PSP, and 19 patients with multiple system atrophy with predominant parkinsonism. Additionally, some patients were diagnosed with dementia with Lewy bodies, vascular parkinsonism, and drug-induced parkinsonism. SNc in the patients with PD and PSP was significantly smaller than that in DCG. LC-CR in the patients with PD was lower than that in DCG; furthermore, LC-CR in the patients with PD was significantly lower than that in the patients with PSP. We found that an area under the receiver-operating characteristic curve, indicating diagnostic efficacy, of 0.85 for LC-CR is a promising biomarker for differentiating PD from PSP.

CONCLUSION

NMI effectively contributes to differentiating neurodegenerative diseases, such as PD and PSP.