Diagnostic value of brain MRI and 18F‐FDG PET in the differentiation of parkinsonian type multiple system atrophy from Parkinson’s disease

Background and purpose: Differentiation between parkinsonian type multiple system atrophy (MSA‐P) and Parkinson’s disease (PD) is important but often difficult. We investigated the diagnostic value of brain magnetic resonance imaging (MRI) and ¹⁸F‐fluorodeoxyglucose positron emission tomography (¹⁸F‐FDG PET) in differentiating MSA‐P from PD. Methods: Twenty‐four patients with MSA‐P (16 probable and 8 possible) and eight patients with PD were included in this study. Results: For analysis using the putaminal findings, the sensitivities were 58.3% by visual analysis of brain MRI, 95.8% by visual analysis of ¹⁸F‐FDG PET, and 79.2% by statistical parametric mapping (SPM) analysis of ¹⁸F‐FDG PET in differentiating MSA‐P from PD; the specificity was 100% for each analysis. Using the putaminal findings, visual analysis of ¹⁸F‐FDG PET had a higher sensitivity compared with brain MRI (P = 0.004) and SPM analysis of ¹⁸F‐FDG PET revealed a tendency towards higher sensitivity compared with brain MRI (P = 0.063). For analysis using both putaminal and infratentorial findings, the sensitivities were 79.2% by visual analysis of brain MRI, 95.8% by visual analysis of ¹⁸F‐FDG PET, 95.8% by SPM analysis of ¹⁸F‐FDG PET in differentiating MSA‐P from PD; the specificity was 100% for each analysis. Conclusion: Both brain MRI and ¹⁸F‐FDG PET showed diagnostic usefulness in differentiating MSA‐P from PD, with ¹⁸F‐FDG PET being more sensitive than brain MRI.     

Diffusion‐weighted imaging in multiple system atrophy: A comparison between clinical subtypes

Multiple system atrophy can be classified into two main types, a Parkinsonian (MSA‐P) and a cerebellar (MSA‐C) variant based on clinical presentation. We obtained diffusion‐weighted magnetic resonance imaging (DWI) in 9 MSA‐P and 12 MSA‐C patients and 11 controls, and correlated DWI changes with disease duration and severity. We found that Trace (D) values in the entire and anterior putamen were significantly higher in MSA‐P than in MSA‐C patients and controls, whereas Trace (D) values in the cerebellum and middle cerebellar peduncle (MCP) were significantly higher in MSA‐C than in MSA‐P patients and controls. Increased disease duration was significantly correlated with increased Trace (D) values in pons of MSA‐P patients, and in cerebellum and MCP of MSA‐C patients. Both UMSARS and UPDRS motor scores positively correlated with entire and posterior putaminal Trace (D) values in MSA‐P patients. The diffusivity changes parallel phenotypical and pathologic differences between MSA‐P and MSA‐C patients, suggesting that DWI is a feasible tool for in vivo evaluation of neurodegeneration in MSA. Based on our findings, Trace (D) measurements in the putamen and pons in MSA‐P patients and in the cerebellum and MCP in MSA‐C patients could serve as quantitative markers for microstructural damage in the course of disease. © 2008 Movement Disorder Society     

Apparent diffusion coefficient of the superior cerebellar peduncle differentiates progressive supranuclear palsy from Parkinson's disease

The early diagnosis of progressive supranuclear palsy (PSP) may be challenging, because of clinical overlapping features with Parkinson's disease (PD) and other parkinsonian syndromes such as the Parkinsonian variant of multiple system atrophy (MSA‐P). Conventional MRI can help in differentiating parkinsonian disorders but its diagnostic accuracy is still unsatisfactory. On the basis of the pathological demonstration of superior cerebellar peduncle (SCP) atrophy in patients with PSP, we assessed the SCP apparent diffusion coefficient (ADC) values in patients with PSP, PD, and MSA‐P in order to evaluate its differential diagnostic value in vivo. Twenty‐eight patients with PSP (14 with possible‐PSP and 14 with probable‐PSP), 15 PD, 15 MSA‐P, and 16 healthy subjects were studied by using diffusion weighted imaging (DWI). ADC was calculated in regions of interest defined in the left and right SCP by two clinically blinded operators. Intrarater (r = 0.98, P < 0.001) and interrater reliability (r = 0.97; P < 0.001) for SCP measurements were high. Patients with PSP had higher SCP rADC values (median 0.98 × 10^?3mm²/s) than patients with PD (median 0.79 × 10^?3 mm²/s, P < 0.001), MSA‐P (median 0.79 × 10^?3 mm²/s, P < 0.001), and healthy controls (median 0.80 × 10^?3 mm²/s, P < 0.001). DWI discriminated patients with PSP from PD and healthy subjects on the basis of SCP rADC individual values (100% sensitivity and specificity) and from patients with MSA‐P (96.4% sensitivity and 93.3% specificity). The higher values of rADC in SCP of patients with PSP correspond with the in vivo microstructural feature of atrophy detected postmortem and provide an additional support for early discrimination between PSP and other neurodegenerative parkinsonisms. © 2008 Movement Disorder Society     

Abnormal metabolic networks in atypical parkinsonism

Spatial covariance analysis has been used with ¹⁸F‐fluorodeoxyglucose (FDG) PET to detect and quantify specific metabolic patterns associated with Parkinson's disease (PD). However, PD‐related patterns cannot necessarily serve as biomarkers of the processes that underlie the atypical parkinsonian syndromes. In this FDG PET study, we used strictly defined statistical criteria to identify disease‐related metabolic patterns in the imaging data from patients with multiple system atrophy (MSA) and progressive supranuclear palsy (PSP), the two most common of these atypical conditions. We found that MSA and PSP were each associated with a specific, highly stable metabolic brain network (P < 0.0001, bootstrap estimation). The MSA‐related pattern was characterized by decreased metabolism in the putamen and cerebellum. The PSP‐related pattern was characterized by metabolic decreases in the brainstem and medial frontal cortex. For both conditions, pattern expression was significantly elevated in patients relative to age‐matched healthy control subjects (P < 0.001). For each condition, we validated the associated disease‐related metabolic pattern by computing its expression on an individual scan basis in two independent patient cohorts, and in one subsequent healthy volunteer cohort. We found that for both MSA and PSP, prospective assessments of pattern expression accurately discriminated patients from controls (P < 0.001). These findings suggest that the major atypical parkinsonian syndromes are associated with distinct patterns of abnormal regional metabolic activity. These disease‐related networks can potentially be used in conjunction with functional brain imaging as quantifiable biomarkers for the assessment of these pathological conditions. © 2008 Movement Disorder Society     

An magnetic resonance imaging T2*‐weighted sequence at short echo time to detect putaminal hypointensity in Parkinsonisms

At 1.5 T, T2*‐weighted gradient echo (GE) sequences are more sensitive in revealing mineral deposition in the basal ganglia than standard T2 weighted sequences. T2*‐weighted GE sequences, however, may detect putaminal hypointensities either in patients affected by parkinsonian syndromes or in healthy subjects. The aim of this study was to identify the magnetic resonance imaging (MRI) T2*‐weighted sequence which more specifically detected putaminal hypointensities differentiating atypical parkinsonian syndromes from Parkinson's disease (PD) and control subjects. In a sample of 38 healthy subjects, we performed three T2*‐weighted GE sequences at increasing time echo (TE; TE = 15 millisecond, TE = 25 millisecond, and echoplanar at TE = 40 millisecond; T2* sequences study). The sequence not showing any putaminal abnormality in the healthy subjects was then used to assess putaminal signal intensity in 189 patients with PD, 20 patients with multiple system atrophy (MSA), 41 patients with progressive supranuclear palsy (PSP), and in 150 age and sex‐matched control subjects. In the T2* sequences study, the T2*‐weighted TE = 15 (T2*/15) did not show any putaminal abnormalities in the healthy subjects. This sequence detected putaminal hypointensities in a significantly higher proportion of patients with MSA (35%, P < 0.05) and PSP (24.4%, P < 0.05) than in patients with PD (5.3%), but in none of the controls. The sensitivity of putaminal hypointensity in T2*/15 sequence was 25.4% for PD, 43.9% for PSP, and 55% for MSA versus controls whereas the specificity was 93.2% for all groups. Despite the suboptimal sensitivity, the high specificity of the T2*/15 sequence performed on routine MRI suggests its usefulness in clinical practice for identifying putaminal hypointensities associated with parkinsonian disorders. © 2010 Movement Disorder Society     

Dopaminergic correlates of metabolic network activity in Parkinson's disease

Parkinson's disease (PD) is associated with distinct metabolic covariance patterns that relate to the motor and cognitive manifestations of the disorder. It is not known, however, how the expression of these patterns relates to measurements of nigrostriatal dopaminergic activity from the same individuals. To explore these associations, we studied 106 PD subjects who underwent cerebral PET with both ¹⁸F‐fluorodeoxyglucose (FDG) and ¹⁸F‐fluoro‐L‐dopa (FDOPA). Expression values for the PD motor‐ and cognition‐related metabolic patterns (PDRP and PDCP, respectively) were computed for each subject; these measures were correlated with FDOPA uptake on a voxel‐by‐voxel basis. To explore the relationship between dopaminergic function and local metabolic activity, caudate and putamen FDOPA PET signal was correlated voxel‐wise with FDG uptake over the entire brain. PDRP expression correlated with FDOPA uptake in caudate and putamen (P < 0.001), while PDCP expression correlated with uptake in the anterior striatum (P < 0.001). While statistically significant, the correlations were only of modest size, accounting for less than 20% of the overall variation in these measures. After controlling for PDCP expression, PDRP correlations were significant only in the posterior putamen. Of note, voxel‐wise correlations between caudate/putamen FDOPA uptake and whole‐brain FDG uptake were significant almost exclusively in PDRP regions. Overall, the data indicate that PDRP and PDCP expression correlates significantly with PET indices of presynaptic dopaminergic functioning obtained in the same individuals. Even so, the modest size of these correlations suggests that in PD patients, individual differences in network activity cannot be explained solely by nigrostriatal dopamine loss. Hum Brain Mapp 36:3575–3585, 2015. © 2015 Wiley Periodicals, Inc.     

A follow‐up study on 6‐[18F]fluoro‐L‐dopa uptake in early Parkinson's disease shows nonlinear progression in the putamen

Sixteen subjects with de novo Parkinson's disease (PD) underwent three 6‐[18F]fluoro‐L‐dopa (Fdopa) positron emission tomography (PET) scans during a follow‐up time of 5 years (mean ± SD 5.5 ± 0.4 years) to study the progression of striatal dopaminergic hypofunction. Throughout the study, the smallest Fdopa uptake values were found in the dorso‐caudal part of the putamen contralateral to the side with dominant motor symptoms. The rate of decline in Fdopa uptake in the contralateral putamen was faster in the beginning of the disease and slowed down as the disease progressed. The annual decline in Fdopa influx constant (Ki, unit × 10^?3 min^?1) was on average 0.5 during the first 2 years and 0.2 during the subsequent 3 years (P = 0.002) in the contralateral putamen. In caudate, the rate of decline in Fdopa values was slower than in the putamen and did not change significantly during the follow‐up time, annual decline in the contralateral caudate being 0.1 between baseline and 2 years and 0.3 between 2 and 5 years (P = 0.4). These results suggest that progression of putaminal dopaminergic hypofuncion in PD follows a nonlinear pattern at least in the contralateral side being faster in the beginning of the disease. © 2009 Movement Disorder Society     

T2*-weighted MRI in diagnosis of multiple system atrophy

Abstract Background Putaminal iron deposition is a histopathological feature of multiple system atrophy (MSA), which is not observed in patients with idiopathic Parkinson's disease (PD). T2*-weighted magnetic resonance imaging (MRI) gradient echo (GE) sequences are sensitive for paramagnetic susceptibility changes and therefore may support the clinical differential diagnosis between MSA and PD. Methods We evaluated putaminal signal intensities on 1.0 Tesla scans of 52 MSA patients, 88 patients with PD and 29 healthy control subjects. Results The typical finding in T2* GE sequences of MSA patients was a signal loss of the dorsolateral putamen, which showed a high specificity (>0.91), but was present in only a subpopulation of patients (sensitivity 0.64–0.69). The combination of the latter with additional presence of a hyperintense lateral rim in fluid attenuated inversion recovery (FLAIR) sequences increased the specificity to 0.97. Using a quantitative evaluation of putaminal signal intensities in defined regions of interest MSA and PD could be discriminated with a diagnostic accuracy (r) of up to 0.82. Conclusion Although the separation of groups remains incomplete, the use of T2*-weighted GE sequences combined with FLAIR may be helpful for the differential diagnosis of MSA versus PD considering its fast application, easy evaluation, broad availability, the specificity of findings and the presence of putaminal signal loss already at early disease stages.     

Quantitative magnetic resonance spectroscopic imaging in Parkinson’s disease,progressive supranuclear palsy and multiple system atrophy

Background and purpose: Magnetic resonance spectroscopy (MRS) allows the measurement of a number of brain tissue metabolites in vivo, including N‐acetylaspartate (NAA), a putative marker of neuronal integrity. Unlike single voxel MRS, magnetic resonance spectroscopic imaging (MRSI) enables quantification of these metabolites simultaneously from multiple anatomically localized voxels. Both single voxel MRS and MRSI allow the absolute quantification of these metabolites and, when combined with tissue segmentation, can give accurate metabolite concentrations even in the presence of partial volume effects from nearby cerebrospinal fluid. Methods: Using MRSI with cubic voxels with a nominal volume of 1.0 cm³, we tested the hypothesis that concentrations of NAA in the basal ganglia in multiple system atrophy (MSA) and progressive supranuclear palsy (PSP) would show differences compared to Parkinson’s disease (IPD). NAA values (in mM) from MRSI voxels centred to the putamen, pallidum and thalamus were obtained from 11 patients with IPD, 11 with MSA‐P, six with MSA‐C, 13 with PSP and 18 controls. The mean concentrations of NAA and its bulk grey and white matter values were also estimated over the whole brain slab. Results: N‐acetylaspartate concentrations in the pallidum, putamen and lentiform nucleus were significantly lower in patients with MSA‐P and PSP compared to IPD and controls. The putaminal values were also significantly reduced in PSP compared to MSA‐P. There were no significant differences between groups in the thalamus and over the whole brain slab. Conclusion: Our findings support the notion that MRSI can potentially quantify basal ganglia cellular pathology in MSA and PSP.     

Diffusion-weighted MRI differentiates the Parkinson variant of multiple system atrophy from PD

OBJECTIVE AND BACKGROUND: Routine MRI as well as MR volumetry and MRS have been shown to contribute to the differential diagnosis of the Parkinson variant of multiple system atrophy (MSA-P) and PD. However, it is currently unknown whether diffusion-weighted imaging (DWI) discriminates these disorders. METHODS: Ten patients with MSA-P (mean age, 64 years) were studied, 11 with PD (mean age, 64 years), and seven healthy volunteers (mean age, 59 years) matched for age and disease duration. Regional apparent diffusion coefficients (rADC) were determined in different brain regions including basal ganglia, gray matter, white matter, substantia nigra, and pons. RESULTS: Patients with MSA-P had higher putaminal rADC (median 0.791 x 10(3)/mm(2)/s) than both patients with PD (median 0.698 x 10(3)/mm(2)/s, p < 0.001) and healthy volunteers (median 0.727 x 10(3)/mm(2)/s, p < 0.001). There were no significant differences in putaminal rADC between patients with PD and healthy volunteers. Moreover, none of the putaminal rADC values in the PD and control group surpassed the lowest value in the MSA-P group. There were no significant group differences in the rADC values in other brain regions such as pons, substantia nigra, globus pallidus, caudate nucleus, thalamus, or gray and white matter. Putaminal rADC values correlated significantly with Unified PD Rating Scale OFF scores in patients with MSA as measured by the Spearman rank test. CONCLUSION: DWI, even if measured in the slice direction only, is able to discriminate MSA-P and both patients with PD and healthy volunteers on the basis of putaminal rADC values. The increased putaminal rADC values in Parkinson variant of multiple system atrophy are likely to reflect ongoing striatal degeneration, whereas most neuropathologic studies reveal intact striatum in PD. Diffusion-weighted imaging may represent a useful diagnostic tool that can provide additional support for a diagnosis of Parkinson variant of multiple system atrophy.     

Use of the Putamen/Caudate Volume Ratio for Early Differentiation between Parkinsonian Variant of Multiple System Atrophy and Parkinson Disease

Background and purpose

Neuropathological studies have demonstrated that multiple system atrophy (MSA) produces selective atrophy of the putamen with sparing of the caudate nucleus, while both structures are spared in idiopathic Parkinson''s disease (PD). In this study we evaluated the clinical efficacy of using putaminal atrophy in brain MRI to differentiate MSA and PD.

Methods

We measured the putamen/caudate volume ratio on brain MRI in 24 patients with MSA and 21 patients with PD. Two clinicians who were blinded to the patients'' diagnoses and to each other''s assessments measured the volume ratio using a computer program.

Results

The measured volume ratios of the two investigators were highly correlated (r=0.72, p<0.0001). The volume ratio was significantly lower in MSA (1.29±0.28) than PD (1.91±0.29, p<0.0001). Setting an arbitrary cutoff ratio of 1.6 resulted in about 90% of patients with MSA falling into the group with a lower ratio, whereas more than 80% of patients with PD belonged to the other group.

Conclusions

The present results demonstrate that putaminal atrophy in MSA as measured on brain MRI represents an effective tool for differentiating MSA from PD.     

Topography of putaminal degeneration in multiple system atrophy: a diffusion magnetic resonance study.

There is neuropathologic evidence that, in early stages of the Parkinson variant of multiple system atrophy (MSA-P), the putamen shows a distinct topographical pathology affecting predominantly the dorsolateral and caudal regions while leaving the rostral to midparts almost intact. We investigated the topographic profile of putaminal degeneration in MSA-P patients in vivo by means of diffusion-weighted imaging (DWI), which has been shown to reveal abnormalities in the basal ganglia of patients with MSA-P compared to patients with PD and healthy controls. For this purpose, regional trace of the diffusion tensor (rTrace(D)) values were determined in the entire, anterior, and posterior putamen in 15 patients with probable MSA-P, in 20 patients with PD, and in 11 healthy volunteers matched for age and disease duration. MSA-P patients had significantly higher rTrace(D) values in entire, anterior, and posterior putamen compared to both controls and PD patients. Trace(D) values were significantly higher in the posterior compared to the anterior putamen in the MSA-P group. There were no significant differences between posterior and anterior putamen in both the control and PD group. Our study demonstrates prominent involvement of the posterior putamen in early disease stages of MSA-P in vivo by assessing putaminal diffusivity with the help of DWI.     

Gaucher disease ascertained through a Parkinson's center: Imaging and clinical characterization

Among the genes implicated for parkinsonism is glucocerebrosidase (GBA), which causes Gaucher disease (GD). Despite a growing literature that GD may present as parkinsonism, neuroimaging, olfaction, and neuropsychological testing have not been extensively reported. We describe transcranial sonography (TCS), 18F‐fluorodopa (F‐dopa) and fluorodeoxyglucose (FDG) Positron emission tomography, olfaction testing, neuropsychological testing, and clinical features in homozygous and compound heterozygous GBA mutation carriers identified through screening of 250 Ashkenazi Jewish parkinsonian individuals treated at a tertiary care center. We identified two individuals with N370S/R496H compound heterozygous mutations and two with N370S homozygous mutations; one individual died before completing detailed evaluation. TCS (n = 3) demonstrated nigral hyperechogenicity that was greater than controls [median area maximal substantia nigra echogenicity (aSNmax) = 0.28 cm² vs. 0.14 cm², P = 0.005], but similar to idiopathic PD (aSNmax = 0.31 cm²). FDG PET (n = 2) demonstrated hypermetabolism of the lentiform nuclei, and F‐fluorodopa PET (n = 2), bilateral reduction in striatal F‐dopa uptake. Olfaction was markedly impaired in the two tested cases, including onset of smell disturbance in adolescence in one. Neuropsychological features (n = 3) were consistent with Parkinson's disease (PD) or diffuse Lewy body disease (DLB). The imaging, neuropsychological and olfactory markers suggest the GD phenotype includes PD with and without features of DLB, marked olfactory loss, nigral hyperechogenicity on TCS, and F‐dopa and FDG PET abnormalities. © 2010 Movement Disorder Society     

Multiple regional 1H-MR spectroscopy in multiple system atrophy: NAA/Cr reduction in pontine base as a valuable diagnostic marker

OBJECTIVE: We performed (1)H-MR spectroscopy ((1)H-MRS) on multiple brain regions to determine the metabolite pattern and diagnostic utility of (1)H-MRS in multiple system atrophy (MSA). METHODS: Examining single voxels at 3.0 T, we studied metabolic findings of the putamen, pontine base, and cerebral white matter in 24 MSA patients (predominant cerebellar ataxia (MSA-C), n = 13), parkinsonism (MSA-P), n = 11), in 11 age and duration matched Parkinson's disease patients (PD) and in 18 age matched control subjects. RESULTS: The N-acetylaspartate to creatine ratio (NAA/Cr) in MSA patients showed a significant reduction in the pontine base (p<0.0001) and putamen (p = 0.02) compared with controls. NAA/Cr in cerebral white matter also tended to decline in long standing cases. NAA/Cr reduction in the pontine base was prominent in both MSA-P (p<0.0001) and MSA-C (p<0.0001), and putaminal NAA/Cr reduction was significant in MSA-P (p = 0.009). It was also significant in patients who were in an early phase of their disease, and in those who showed no ataxic symptoms or parkinsonism, or did not show any MRI abnormality of the "hot cross bun" sign or hyperintense putaminal rims. NAA/Cr in MSA-P patients was significantly reduced in the pontine base (p = 0.001) and putamen (p = 0.002) compared with PD patients. The combined (1)H-MRS in the putamen and pontine base served to distinguish patients with MSA-P from PD more clearly. CONCLUSIONS:(1)H-MRS showed widespread neuronal and axonal involvement in MSA. The NAA/Cr reduction in the pontine base proved highly informative in the early diagnosis of MSA prior to MRI changes and even before any clinical manifestation of symptoms.     

Reduced alpha‐synuclein in cerebrospinal fluid in synucleinopathies: Evidence from a meta‐analysis

Alpha‐synuclein plays a key role in the pathology of synucleinopathies including Parkinson's disease (PD) and multiple system atrophy (MSA). However, whether alpha‐synuclein level in cerebrospinal fluid (CSF) could distinguish synucleinopathies from progressive supranuclear palsy (PSP) is still a contentious issue. A comprehensive literature search yielded nine eligible studies. We expressed the between‐group difference of the concentration of alpha‐synuclein in CSF as the standardized mean difference. The proportion of variation attributable to heterogeneity was computed and expressed as I². Nine studies involved 537 controls, 843 PD, 130 MSA, and 98 PSP patients. The overall effect of PD on alpha‐synuclein in CSF was significantly different from normal control or disease control (standardized mean difference = –0.67, P < 0.00001). These studies were heterogeneous (I² = 40%). Alpha‐synuclein in CSF in MSA was significantly reduced relative to controls with heterogeneous studies (standardized mean difference = –0.75, P < 0.0001; I² = 62%). In contrast, no significant difference of alpha‐synuclein in CSF was observed between PSP and controls with heterogeneous studies (standardized mean difference = –0.28, P = 0.13; I² = 53%). Alpha‐synuclein in CSF was significantly reduced in synucleinopathies compared with PSP (“PD vs. PSP”: standardized mean difference = –0.38, P = 0.001; “MSA vs. PSP”: standardized mean difference = –0.66, P < 0.00001). The included studies were homogeneous (I² = 0%). Our study showed that alpha‐synuclein levels in CSF in synucleinopathies was significantly lower than in PSP. This finding provides insights into the pathophysiological difference between synucleinopathies and PSP as well as possibility of development of a tool for differential diagnosis between MSA and PSP using enzyme‐linked immunosorbent assay (ELISA) and similar methods. © 2014 International Parkinson and Movement Disorder Society     

Combination of dopamine transporter and D2 receptor SPECT in the diagnostic evaluation of PD, MSA, and PSP.

It is often difficult to differentiate clinically between Parkinson's disease (PD), multiple system atrophy (MSA), and progressive supranuclear palsy (PSP).The objective of this work was to investigate whether combined pre‐ and postsynaptic dopaminergic single photon emission computed tomography (SPECT) scanning can reliably demonstrate changes in the nigrostriatal dopaminergic system and help differentiate between normal controls, PD, MSA, and PSP patients. We performed SPECT evaluation of the dopamine transporter (DAT) and dopamine D2 receptors (D2). SPECT scans using [¹²³I]β‐CIT (for DAT) and [¹²³I]IBF (for D2) were performed in 18 patients with PD (12 dopa‐naïve and 6 on levodopa and/or dopamine agonists), 7 with MSA of the striatonigral degeneration type, 6 with PSP, and 29 normal controls. Antiparkinsonian drugs were withheld for at least 12 hours before the scans. DAT and D2 binding potentials (Rv = V₃/V₂) were measured for caudate, anterior, and posterior putamen on the sides ipsilateral and contralateral to the worst motor symptoms. DAT binding in the posterior putamen was markedly reduced in all patients. However, D2 binding in posterior putamen was significantly increased in dopa‐untreated PD, being greater than the normal range in 4 of 12 (33%), and it was significantly reduced in MSA, being below the normal range in 5 of 7 (71%). None of the patients with PD showed reduced D2 binding below the normal range in posterior putamen. The degree of DAT binding could not discriminate between the patient groups. The ratio of posterior putamen to caudate percentage D2 Rv compared with the controls showed an opposite pattern between PD or PSP and MSA; the caudate was greater in 16 of 18 with PD and 6 of 6 with PSP, whereas caudate was less in 5 of 7 with MSA. These findings suggest that DAT SPECT may be useful in differentiating parkinsonism from controls and D2 SPECT in further differentiating MSA from Parkinson's disease and possibly PSP. © 2002 Movement Disorder Society.     

Therapeutic effect of repetitive transcranial magnetic stimulation in Parkinson's disease: Analysis of [11C] raclopride PET study

Repetitive transcranial magnetic stimulation (rTMS) has been used as a potential therapeutic tool in Parkinson's disease (PD). However, the therapeutic value and/or the placebo effect of rTMS on PD remain to be elucidated. To investigate the therapeutic value and/or placebo effect of rTMS in PD, we compared the motor section of unified PD rating scale (UPDRS III) and the amount of extracellular dopamine concentration using [¹¹C] raclopride PET before and after two sessions of rTMS in 9 PD patients. During a consecutive 2 days while off‐medication, two series of 15 trains of 5 Hz‐frequency rTMS (intensity, 90% of the resting motor threshold) were applied to the hand area of more severely symptomatic motor cortex (MC). After unilateral rTMS of MC, mean raclopride binding potentials (BPs) were reduced not only in putaminal and caudate areas on the stimulated side (?4.9% and ?6.5%, respectively) (P > 0.05) but also in putaminal and caudate areas of nonstimulated hemispheres (?6.6%, P > 0.05 and ?12.1%, P = 0.049, respectively). UPDRS III scores were significantly decreased (35.0 ± 14.1 to 32.0 ± 13.4, P = 0.049). A reduction of raclopride BP in nonstimulated ventral striatum by unilateral rTMS supports the placebo response during rTMS. © 2007 Movement Disorder Society     

Motor‐related circuit dysfunction in MSA‐P: Usefulness of combined whole‐brain imaging analysis

The aim of this study was to evaluate in vivo changes in the brain's macro‐ and microstructure (notably in the motor system) in the parkinsonian variant of multiple system atrophy (MSA‐P) and in Parkinson's disease (PD) and to characterize the cerebral anatomical differences between the two conditions. We used a combination of voxel‐based morphometry (VBM) and whole‐brain, voxel‐based diffusion tensor imaging analysis (VB‐DTI). Forty‐seven right‐handed subjects (14 MSA‐P patients, 19 PD patients, and 14 controls) were evaluated using VBM and VB‐DTI in an analysis of covariance (ANCOVA) with a significance threshold set to P < 0.005. In MSA‐P patients, VBM analysis revealed a lower density of grey matter (GM) in a motor‐related circuit (especially in the left primary motor cortex, PMC), relative to PD patients, and in the left supplementary motor area (SMA), relative to controls). Diffusion tensor imaging analysis revealed lower fractional anisotropy (FA) values in the left PMC and the right cerebellum in MSA‐P patients, compared with controls. Using a volumetric diffusion technique, our study revealed selective tissue degeneration in motor circuits, regardless of the volume loss detected in VBM and in agreement with pathology reports and clinical motor characteristics. Our findings suggest that MSA‐P is characterized by both macro‐ and microstructural changes in the sensorimotor circuit. © 2009 Movement Disorder Society     

Characterization and diagnostic potential of diffusion tractography in multiple system atrophy

IntroductionMicrostructural integrity of the middle cerebellar peduncle (MCP) and the putamen captured by diffusion-tensor imaging (DTI) is differentially affected in the parkinsonian and cerebellar variants of multiple system atrophy (MSA-P, MSA-C) compared to Parkinson's disease (PD). The current study applied DTI and tractography in order to 1) characterize the distribution of DTI metrics along the tracts of the MCP and from the putamen in MSA variants, and 2) evaluate the usefulness of combining these measures for the differential diagnosis of MSA-P against PD in the clinical setting.MethodsTwenty-nine MSA patients (MSA-C, n = 10; MSA-P, n = 19), with a mean disease duration of 2.8 ± 1.7 years, 19 PD patients, and 27 healthy controls (HC) were included in the study. Automatized tractography with a masking procedure was employed to isolate the MCP tracts. DTI measures along the tracts of the MCP and within the putamen were acquired and jointly used to classify MSA vs. PD, and MSA-P vs. PD. Putamen volume was additionally tested as classification feature in post hoc analyses.ResultsDTI measures within the MCP and putamen showed significant alterations in MSA variants compared to HC and PD. Classification accuracy for MSA vs. PD and MSA-P vs PD using diffusion measures was 91.7% and 89.5%, respectively. When replacing the putaminal DTI measure by a normalized measure of putamen volume classification accuracy improved to 95.8% and 94.7%, respectively.ConclusionMultimodal information from MCP tractography and putamen volume yields excellent diagnostic accuracy to discriminate between early-to-moderately advanced patients with MSA and PD.     

Nonlinear progression of Parkinson disease as determined by serial positron emission tomographic imaging of striatal fluorodopa F 18 activity

BACKGROUND: The investigation of disease progression provides important information on the dynamics of cell death in Parkinson disease (PD). OBJECTIVE: To determine the progression of dopaminergic impairment in PD with the use of positron emission tomography (PET). DESIGN: Longitudinal prospective cohort study with a follow-up period of 64.5 +/- 22.6 months (mean +/- SD). SETTING: University hospital. PATIENTS: A consecutive sample of patients with PD (N = 31; age at symptom onset, 53.6 +/- 11.3 years) with a wide range of symptom duration and severity at the time of study entry. INTERVENTIONS: Investigation by serial fluorodopa F 18 ([(18)F]fluorodopa) PET as a marker for striatal dopaminergic function. MAIN OUTCOME MEASURES: Changes in caudate and putaminal [(18)F]fluorodopa influx constant (K(i)) values. RESULTS: In patients with PD, the decline rate of putaminal [(18)F]fluorodopa K(i) correlated inversely with disease duration before study inclusion (r = -0.46, P = .01) and positively with baseline K(i) values (r = 0.44, P = .01), indicating a negative exponential loss of dopamine neurons. Annual disease progression rates ranged from 4.4% in the caudate nucleus to 6.3% in the putamen. A mean preclinical period of 5.6 +/- 3.2 years was calculated with symptom onset at a putaminal K(i) threshold of 69% from controls. Assuming nonlinear progression kinetics, the required sample size to prove neuroprotection with the use of [(18)F]fluorodopa PET was found to increase strongly with the preceding symptom duration of study subjects. CONCLUSION: These data suggest that the neurodegenerative process in PD follows a negative exponential course and slows down with increasing symptom duration, contradicting the long-latency hypothesis of PD.