To prospectively assess sensitivity and specificity of magnetic resonance (MR) imaging measurements of midbrain, pons, middle cerebellar peduncles (MCPs), and superior cerebellar peduncles (SCPs) for differentiating progressive supranuclear palsy (PSP) from Parkinson disease (PD) and Parkinson variant of multiple system atrophy (MSA-P), with established consensus criteria as reference standard. All study participants provided informed consent; study was approved by the institutional review board. Pons area, midbrain area, MCP width, and SCP width were measured in 33 consecutive patients with PSP (16 possible, 17 probable), 108 consecutive patients with PD, 19 consecutive patients with MSA-P, and 50 healthy control participants on T1-weighted MR images. The pons area-midbrain area ratio (P/M) and MCP width-SCP width ratio (MCP/SCP) were also used, and an index termed MR parkinsonism index was calculated [(P/M).(MCP/SCP)]. Differences in MR imaging measurements among groups were evaluated with Kruskal-Wallis test, Mann-Whitney U test, and Bonferroni correction. Midbrain area and SCP width in patients with PSP (23 men, 10 women; mean age, 69.3 years) were significantly (P < .001) smaller than in patients with PD (62 men, 46 women; mean age, 65.8 years), patients with MSA-P (five men, 14 women; mean age, 64.0 years), and control participants (25 men, 25 women; mean age, 66.6 years). P/M and MCP/SCP were significantly larger in patients with PSP than in patients in other groups and control participants. All measurements showed some overlap of values between patients with PSP and patients from other groups and control participants. MR parkinsonism index value was significantly larger in patients with PSP (median, 19.42) than in patients with PD (median, 9.40; P < .001), patients with MSA-P (median, 6.53; P < .001), and control participants (median, 9.21; P < .001), without overlap of values among groups. No patient with PSP received a misdiagnosis when the index was used (sensitivity and specificity, 100%). The MR parkinsonism index can help distinguish patients with PSP from those with PD and MSA-P on an individual basis.

Clinical differentiation of parkinsonian syndromes such as the Parkinson variant of multiple system atrophy (MSA-P) and progressive supranuclear palsy (PSP) from Parkinson's disease is difficult in the early stage of the disease. In order to identify objective markers for differential diagnosis, we studied these three groups of patients with diffusion-weighted MRI (DWI). Sixteen MSA-P patients, 16 with PSP, 16 with Parkinson's disease and 15 healthy volunteers were studied. Regional apparent diffusion coefficients (rADC) were determined in different brain regions including basal ganglia, thalamus, white matter, pons and middle cerebellar peduncles (MCPs). rADC calculated in the MCP completely differentiated MSA-P patients (median: 0.93 × 10⁻³ mm²/s) from PSP patients (median: 0.82 × 10⁻³ mm²/s, P < 0.001), Parkinson's disease patients (median: 0.79 × 10⁻³ mm²/s, P < 0.001) and healthy volunteers (median: 0.81 × 10⁻³ mm²/s, P < 0.001). Other regions considered showed an overlapping among groups. DWI discriminates MSA-P from PSP and Parkinson's disease and healthy volunteers on the basis of MCP rADC values. These in vivo results confirm the pathological findings that the majority of MSA-P patients have moderate or severe degenerative changes not only in the nigrostriatal but also in the olivopontocerebellar systems. Our findings indicate that, in order to substantially contribute to the in vivo differential diagnosis of MSA-P, PSP and Parkinson's disease, rADC measurements should not be limited to the basal ganglia but should also include the MCP.

Objective: The aim of our study was to investigate the microstructural integrity of brain regions functionally involved in the tremor loop in patients with familial essential tremor (FET), using diffusion tensor imaging (DTI).

BACKGROUND AND PURPOSE: Essential tremor (ET) is a slowly progressive disorder characterized by postural and kinetic tremors most commonly affecting the forearms and hands. Several lines of evidence from physiologic and neuroimaging studies point toward a major role of the cerebellum in this disease. Recently, voxel-based morphometry (VBM) has been proposed to quantify cerebellar atrophy in ET. However, VBM was not originally designed to study subcortical structures, and the complicated anatomy of the cerebellum may hamper the automatic processing of VBM. The aim of this study was to determine the efficacy and utility of using automated subcortical segmentation to identify atrophy of the cerebellum and other subcortical structures in patients with ET.

To prospectively assess if middle cerebellar peduncle (MCP) atrophy, evaluated at magnetic resonance (MR) imaging, can help differentiate multiple system atrophy (MSA) from Parkinson disease (PD). All participants provided informed consent for participation in the study, which was approved by the institutional review board. Sixteen consecutive patients with MSA, 26 consecutive patients with PD, and 14 healthy control subjects were examined with MR imaging. Images were interpreted independently by two experienced neuroradiologists blinded to clinical information, who visually inspected the images for the presence or absence of putaminal atrophy, putaminal hypointensity, slitlike hyperintensity in the posterolateral margin of the putamen, brainstem atrophy, hyperintensity of the MCP, and cruciform hyperintensity of the pons. Measurements of MCP width on T1-weighted volumetric spoiled gradient-echo images were performed in all subjects. Differences in MCP width among the groups were evaluated by using the Kruskall-Wallis test, followed by the Mann-Whitney U test for multiple comparisons and Bonferroni correction. All patients (mean age, 63.88 years; range, 55-72 years) with MSA had at least one of the features commonly observed in this disease on MR images, whereas control subjects (mean age, 66.93 years; range, 61-77 years) and all but one patient with PD (mean age, 65.31 years; range, 51-79 years) had normal MR images. The average MCP width was significantly smaller in patients with MSA (6.10 mm+/-1.18 [standard deviation]) than in those with PD (9.32 mm+/-0.77, P<.001) or control subjects (9.80 mm+/-0.66, P<.001). Measurement of MCP width on MR images may be useful for distinguishing patients with MSA from those with PD.