Motor imagery (MI) is defined as mental execution without any actual movement. While healthy adults usually show temporal equivalence, i.e., isochrony, between the mental simulation of an action and ...its actual performance, neurological disorders are associated with anisochrony. Unlike in patients with stroke and Parkinson disease, only a few studies have investigated differences of MI ability in multiple sclerosis (MS). However, the relationship among disease severity, anisochrony and brain activation patterns during MI has not been investigated yet. Here, we propose to investigate MI in MS patients using fMRI during a behavioral task executed with dominant/non-dominant hand and to evaluate whether anisochrony is associated with disease severity. Thirty-seven right-handed MS patients, 17 with clinically isolated syndrome (CIS) suggestive of MS and 20 with relapsing-remitting MS (RR-MS) and 20 right-handed healthy controls (HC) underwent fMRI during a motor task consisting in the actual or imaged movement of squeezing a foam ball with the dominant and non-dominant hand. The same tasks were performed outside the MRI room to record the number of actual and imagined ball squeezes, and calculate an Index of performance (IP) based on the ratio between actual and imagined movements. IP showed that a progressive loss of ability in simulating actions (i.e., anisochrony) more pronounced for non-dominant hand, was found as function of the disease course. Moreover, anisochrony was associated with activation of occipito-parieto-frontal areas that were more extensive at the early stages of the disease, probably in order to counteract the changes due to MS. However, the neural engagement of compensatory brain areas becomes more difficult with more challenging tasks, i.e., dominant vs. non-dominant hand, with a consequent deficit in behavioral performance. These results show a strict association between MI performance and disease severity, suggesting that, at early stages of the disease, anisochrony in MI could be considered as surrogate behavioral marker of MS severity.
Pure/predominant upper motor neuron (pUMN) and lower motor neuron (pLMN) diseases have significantly better prognosis compared to amyotrophic lateral sclerosis (ALS), but their early differentiation ...is often challenging. We therefore tested whether a multimodal characterization approach embedding clinical, cognitive/behavioral, genetic, and neurophysiological data may improve the differentiation of pUMN and pLMN from ALS already by the time of diagnosis. Dunn’s and chi-squared tests were used to compare data from 41 ALS, 34 pLMN, and 19 pUMN cases with diagnoses confirmed throughout a 2-year observation period. Area under the curve (AUC) analyses were implemented to identify the finest tools for phenotypes discrimination. Relative to ALS, pLMN showed greater lower limbs weakness, lower UMN burden, and progression rate (p < 0.001−0.04). PUMN showed a greater frequency of lower limbs onset, higher UMN burden, lower ALSFRS-r and MRC progression rates (p < 0.001−0.03), and greater ulnar compound muscle action potential (CMAP) amplitude and tibial central motor conduction time (CMCT) (p = 0.05−0.03). The UMN progression rate was the finest measure to identify pLMN cases (AUC = 90%), while the MRC progression rate was the finest tool to identify pUMN (AUC = 82%). Detailed clinical and neurophysiological examinations may significantly improve MNDs differentiation, facilitating prognosis estimation and ameliorating stratification strategies for clinical trials enrollment.
Background
In multiple sclerosis, the correlation between white matter lesion volumes (LV) and expanded disability status scale (EDSS) is at best moderate, leading to the “clinico-radiological ...paradox”, influenced by many factors, including the lack of information on the spatial localisation of each lesion on synthetic metrics such as LV. We used a probabilistic approach to provide the volume of WM tracts that may be disconnected by lesions and to evaluate its correlation with EDSS.
Methods
Forty-five patients (aged 37.4 ± 6.8 years, mean ± standard deviation; 30 females; 29 relapsing-remitting, 16 progressive) underwent 3-T magnetic resonance imaging. Both LV and the volume of the tracts crossing the lesioned regions (disconnectome volume, DV) were calculated using BCBtoolkit and correlated with EDSS.
Results
T1-weighted LV and DV significantly correlated with EDSS (
p
≤ 0.006
r
≥ 0.413) as it was for T2-weighted LV and T2-weighted DV (
p
≤ 0.004
r
≥ 0.430), but only T1-weighetd and T2-weighted DVs were EDSS significant predictors (
p
≤ 0.001). The correlations of T1-weighted and T2-weighted LV with EDSS were significantly mediated by DV, while no effect of LV on the EDSS-DV correlation was observed.
Conclusion
The volume of disconnected WM bundles mediates the LV-EDSS correlation, representing the lonely EDSS predictor.
MR diffusion imaging in ischemic stroke Fung, Steve H; Roccatagliata, Luca; Gonzalez, R Gilberto ...
Neuroimaging clinics of North America,
05/2011, Letnik:
21, Številka:
2
Journal Article
Recenzirano
Diffusion-weighted MRI provides image contrast that is dependent on the molecular motion of water. Diffusion-weighted imaging is the most reliable method for early detection of cerebral ischemia, for ...the definition of infarct core, and for the differentiation of acute ischemia from other disease processes that mimic stroke. Diffusion tensor imaging and diffusion kurtosis imaging may offer additional diagnostic information on the microstructural status of tissue. This review discusses the development and applications of diffusion-weighted imaging, diffusion tensor imaging, and diffusion kurtosis imaging in acute and chronic ischemia.
In acute stroke patients, the presence of a hyperdense middle cerebral artery sign on unenhanced CT is a specific but insensitive indicator of acute thrombosis. Our purpose was to determine whether ...the hyperdense basilar artery (HDBA) sign has utility in detecting thrombosis and predicting outcome in patients presenting with signs and symptoms of posterior circulation stroke.
Unenhanced CT scans obtained within 24 hours of symptom onset in 95 patients with suspected posterior circulation stroke were reviewed. Three neuroimagers blinded to clinical outcome and results of the concurrent CT angiography (which served as the reference standard) rated presence of HDBA sign on a 5-point scale for level of certainty (1=definitely absent; 5=definitely present). Receiver operating characteristic curve analysis was performed. Short-term outcome was measured by discharge National Institute of Health Stroke Scale (NIHSS) scores; long-term outcome was measured by 6-month modified Rankin score (dichotomized, poor outcome defined as modified Rankin score >2). The following variables were correlated with short-term and long-term outcome by univariate analysis: HDBA sign, age, sex, time from stroke onset to imaging, admission NIHSS, history of stroke/TIA, atrial fibrillation, coronary artery disease, hypertension, diabetes, hypercholesterolemia, tobacco use, and thrombolysis. Variables showing correlation with P<0.1 were included in multiple regression analysis.
Using a level of certainty cutoff score of >/=4 (probable, definite), HDBA sign had 71% sensitivity, 98% specificity, 94% accuracy, 83% positive predictive value, and 95% negative predictive value for basilar artery occlusion. In univariate analysis, factors significantly correlated with discharge NIHSS were: admission NIHSS (P<0.0001; r=0.77), HDBA sign (P=0.01), and diabetes (P=0.02). Factors showing significant correlation or association with poor long-term outcome were age (P=0.02), admission NIHSS (P=0.007), HDBA sign (P=0.02), and history of stroke or TIA (P=0.007). The odds ratio of HDBA sign for predicting poor long-term outcome was 5.3 (95% CI, 1.1-33.3). In multiple regression analysis, the only independent predictors of discharge NIHSS were admission NIHSS (P<0.0001) and HDBA sign (P=0.004). Significant independent predictors of poor long-term outcome were age (P=0.02), admission NIHSS (P=0.008), history of stroke/TIA (P=0.03), and HDBA sign (P=0.05).
In patients presenting with a high pretest probability of posterior circulation stroke based on clinical symptoms, the presence of the HDBA sign on unenhanced CT is a strong predictor of basilar artery thrombosis, and both short- and long-term outcome.
The partial volume effect (PVE) complicates PET studies of neurodegenerative diseases, since a decreased 18F-FDG retention might be influenced by atrophy-related changes of cortical regions. Multiple ...partial volume correction (PVC) methods have been therefore developed, but their application in amyotrophic lateral sclerosis (ALS) is still rare. Additionally, even if metabolic changes have been established in ALS, no study yet has investigated how these may be influenced by aging and disease course. The aim of the present study was therefore to apply and compare multiple PVC approaches to explore aging and disease course-related hypometabolism in ALS.
PET and MRI data from 15 ALS patients were analyzed using PETSurfer to implement 4 distinct PVC methods: noPVC, Meltzer (MZ), Müller-Gärtner (MG) and Symmetric Geometric Transfer Matrix (SGTM). For each method and Region of Interest (ROI), the 18F-FDG value was regressed against subject age and disease duration.
MG/SGTM application almost halved the number of regions showing a significant age-related hypometabolism, while the same effect was not observed for disease course, where only the distribution of identified regions varied. Three distinct patterns emerged: regions showing a significant age/disease course-related effect across all the different methods, regions yielding significance only with MG/SGTM application, and regions maintaining significance only with noPVC/MZ application.
Significant changes in the distribution of aging and disease course-related hypometabolism were observed when the effect of the underlying structural status was considered, supporting the need for investigate the impact of PVE on PET-assessed metabolic changes in clinical and research settings.
Display omitted
•4 PVC methods were compared to evaluate aging and disease course-related hypometabolism in ALS.•3 patterns of significance emerged across ROIs: with all PVC methods, only with MG/SGTM, and only with noPVC/MZ.•The PVE exerts a significant impact on the detection of metabolism alterations distribution.
Background
Assessment of nigrostriatal degeneration is a key element to discriminate between dementia with Lewy bodies (DLB) and Alzheimer disease (AD), and it is often evaluated using ioflupane (
...123
I-FP-CIT) single-photon emission computed tomography (SPECT). Given the limited availability of
123
I-FP-CIT SPECT, we evaluated if a mask-based approach to nigroputaminal magnetic resonance imaging (MRI) diffusion-weighted tractography could be able to capture microstructural changes reflecting nigroputaminal degeneration in DLB.
Methods
A nigroputaminal bundle mask was delineated on 12 healthy volunteers (HV) and applied to MRI diffusion-weighted data of 18 subjects with DLB, 21 subjects with AD and another group of 12 HV. The correlation between nigroputaminal fractional anisotropy (FA) values and
123
I-FP-CIT SPECT findings was investigated. Shapiro-Wilk, ANOVA, ANCOVA, and parametric correlation statistics as well as receiver operating characteristic (ROC) analysis were used.
Results
DLB patients showed a higher nigroputaminal FA values compared with both AD and HV-controls groups (
p
= 0.001 for both comparisons), while no difference was observed between HV-controls and AD groups (
p
= 0.450); at ROC analysis, the area under the curve for the discriminating DLB and AD subjects was 0.820; FA values correlated with
123
I-FP-CIT values (on the left,
r
= -0.670; on the right,
r
= -720). No significant differences were observed for the FA of the corticospinal tract across the three groups (
p
= 0.740).
Conclusions
In DLB, nigroputaminal degeneration could be reliably assessed on MRI diffusion scans using a mask of nigroputaminal bundle trajectory. Nigroputaminal FA in DLB patients correlated with
123
I-FP-CIT values data may allow to differentiate these patients from AD patients and HV-controls.
(1) Although guidelines about the use of MRI sequences for Multiple Sclerosis (MS) diagnosis and follow-up are available, variability in acquisition protocols is not uncommon in everyday clinical ...practice. The aim of this study was to evaluate the real-world application of MS imaging guidelines in different settings to clarify the level of adherence to these guidelines. (2) Via an on-line anonymous survey, neuroradiologists (NR) were asked about MRI protocols and parameters routinely acquired when MS patients are evaluated in their center, both at diagnosis and follow-up. Furthermore, data about report content and personal opinions about emerging neuroimaging markers were also retrieved. (3) A total of 46 participants were included, mostly working in a hospital or university hospital (80.4%) and with more than 10 years of experience (47.9%). We found a relatively good adherence to the suggested MRI protocols regarding the use of T2-weighted sequences, although almost 10% of the participants routinely acquired 2D sequences with a slice thickness superior to 3 mm. On the other hand, a wider degree of heterogeneity was found regarding gadolinium administration, almost routinely performed at follow-up examination (87.0% of cases) in contrast with the current guidelines, as well as a low use of a standardized reporting system (17.4% of cases). (4) Although the MS community is getting closer to a standardization of MRI protocols, there is still a relatively wide heterogeneity among NR, with particular reference to contrast administration, which must be overcome to guarantee an adequate quality of patients’ care in MS.
Background
Partially thrombosed intracranial aneurysms (PTIAs) are different from saccular or nonthrombosed giant or large aneurysms, as they are characterized by multiple intramural thrombotic ...phenomena related to recurrent vessel wall dissections.
Methods
We retrospectively reviewed clinical and radiological files of 23 consecutive patients with PTIAs (mean age 49.3 years). Twenty-two lesions were studied by magnetic resonance imaging (MRI). Patients were managed by endovascular treatments, medically with steroids, or conservatively.
Results
Thirteen patients presented with progressive neurological symptoms. Subarachnoid hemorrhage was suspected but not proven in three. At MRI, 90.9% of PTIAs caused mass effect; perilesional T2 hypersignal compatible with edema was evident in 13.6%. Aneurysmal wall enhancement was detectable in 63.2% of the PTIAs and considered a marker of inflammatory processes. Parent artery occlusion was performed in seven patients with clinical improvement in six. Selective coiling was proposed in three patients (one improved, one remained stable, and one experienced symptoms progression). Three patients were treated with steroids and improved. Ten patients were managed conservatively: eight because spontaneous thrombosis of the lesion had been diagnosed and two because of clinical and radiological stability.
Conclusions
The natural history of PTIAs is different from other aneurysms. They most commonly present with progressive neurological symptoms due to mass effect. MRI properly diagnoses PTIAs and allows precise follow-up, more accurately than angiography because it detects prominent “abluminal” features indicating inflammation and neovascularization. Spontaneous thrombosis is part of the natural history of PTIAs and it should be taken in consideration when discussing the therapeutic management.
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