Characteristic MRI findings in multiple system atrophy: comparison of the three subtypes.

We reviewed MRI findings in 29 patients with probable multiple system atrophy (MSA) to see whether there were common and or less common neuroradiological findings in the various clinical subtypes. We divided the patients into three clinical subtypes according to initial and predominant symptoms: 14 with olivopontocerebellar atrophy (OPCA), eight with the Shy-Drager syndrome (SDS) and seven with striatonigral degeneration (SND). The patients showed atrophy of the brain stem and cerebellum, high signal on T2-weighted images of the base of the pons and middle cerebellar peduncles, high and low signal on T2-weighted images of the putamen and atrophy of frontal and parietal lobes. The degree of atrophy of the middle cerebellar peduncle and cerebellum was greater in OPCA patients and a high-signal lateral rim to the putamen more frequent in SND. However, all findings were observed in all subtypes, and the degrees of atrophy of the putamen and pons and the frequency of high signal in the base of the pons were similar in the subtypes. We also found atrophy of the cerebral hemispheres, especially the frontal and parietal lobes, but its degree was not significantly different in the various subtypes. Our findings suggest that, although MSA can be divided clinically into three subtypes, most of the features on MRI are common and overlap in the subtypes, independently of the clinical presentation.

Abnormal signals on proton density-weighted MRI of the superior cerebellar peduncle in progressive supranuclear palsy.

OBJECTIVE: To assess MRI signal abnormalities of the superior cerebellar peduncle (SCP) in progressive supranuclear palsy (PSP) patients. MATERIAL AND METHODS: Signal changes were examined on proton density-weighted images (PDWI) and on T2-weighted images (T2WI) of SCP in 9 PSP patients, and findings were compared to those in 20 Parkinson's disease patients and 20 age-matched control subjects. RESULTS: We observed effacement or lack of clarity of the low signal on PDWI in SCP in 4 of 9 PSP patients, but not in any of the Parkinson's disease patients or control subjects. These signal changes were not observed on T2WI. CONCLUSIONS: The signal changes on PDWI may be a specific finding reflecting demyelination and gliosis of SCP in PSP. Our findings suggest that evaluation of SCP on PDWI may be helpful in the diagnosis of PSP patients.

Apparent diffusion coefficient measurements in progressive supranuclear palsy.

We measured the apparent diffusion coefficient (ADC), using diffusion-weighted imaging (DWI) and signal intensity on T2-weighted MRI in the cerebral white matter of patients with progressive supranuclear palsy (PSP) and age-matched normal subjects. In PSP, ADC in the prefrontal and precentral white matter was significantly higher than in controls. There was no significant difference in signal intensity on T2-weighted images. The ADC did correlate with signal intensity. The distribution of the elevation of ADC may be the consequence of underlying pathological changes, such as neurofibrillary tangles or glial fibrillary tangles in the cortex. Our findings suggest that ADC measurement might be useful for demonstrating subtle neuropathological changes.

Serial diffusion-weighted imaging in MELAS.

Clinical features of mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS) resemble those of cerebral infarcts, but the pathogenesis of infarct-like lesions is not fully understood. To characterise these infarct-like lesions, we studied two patients with MELAS using diffusion-weighted (DWI) MRI before and after stroke-like episodes and measured the apparent diffusion coefficient (ADC) in the new infarct-like lesions. These gave high signal on DWI and had much higher ADC than normal-appearing regions. The ADC remained high even 30 days after a stroke-like episode then decreased in lesions, with or without abnormality as shown by conventional MRI. We speculate that early elevation of ADC in the acute or subacute phase reflects vasogenic rather than cytotoxic edema. The ADC of the lesions, which disappeared almost completely with clinical improvement, returned to normal levels, which may reflect tissue recovery without severe damage. To our knowledge, this is the first study of DWI in MELAS.

SPECT image analysis using statistical parametric mapping in patients with Parkinson's disease.

UNLABELLED: This study investigated alterations in regional cerebral blood flow (rCBF) in patients with Parkinson's disease using statistical parametric mapping (SPM). METHODS: Noninvasive rCBF measurements using 99mTc-ethyl cysteinate dimer (ECD) SPECT were performed on 28 patients with Parkinson's disease and 48 age-matched healthy volunteers. The Parkinson's disease patients were divided into two groups, 16 patients with Hoehn and Yahr stage I or II and 12 patients with Hoehn and Yahr stage III or IV. We used the raw data (absolute rCBF parametric maps) and the adjusted rCBF images in relative flow distribution (normalization of global CBF for each subject to 50 mL/100 g/min with proportional scaling) to compare these groups with SPM. RESULTS: In patients with stage I or II Parkinson's disease, we found a diffuse decrease in absolute rCBF in the whole brain with sparing of the central gray matter, hippocampus and right lower temporal lobe compared with healthy volunteers. Adjusted rCBF increased in both putamina and the right hippocampus. In patients with stage III or IV disease, rCBF decreased throughout the whole brain. Adjusted rCBF increased bilaterally in the putamina, globi pallidi, hippocampi and cerebellar hemispheres (dentate nuclei) and in the left ventrolateral thalamus, right insula and right inferior temporal gyrus. CONCLUSION: SPM analysis showed that significant rCBF changes in Parkinson's disease accompanied disease progression and related to disease pathophysiology in the functional architecture of thalamocortex-basal ganglia circuits and related systems.

Diffusion-weighted and magnetization transfer imaging of the corpus callosum in Alzheimer's disease.

We investigated structural changes of the corpus callosum in patients with Alzheimer's disease (AD) using sagittal diffusion-weighted (DW) and magnetization transfer (MT) imaging. Patients with AD (n=23) had a significantly decreased area only in the posterior portion of the corpus callosum. Apparent diffusion coefficient (ADC) values perpendicular to the commisural fiber orientation were significantly higher in the anterior portion of the corpus callosum without definite atrophy, as well as in the posterior portion with significant atrophy, in patients with AD than in controls (n=16) and thus diffusion in these regions showed a significantly lower degree of anisotropy in patients than in controls. MT ratios were also significantly lower in patients with AD in the anterior and posterior portions of the corpus callosum than in controls. These findings probably reflect structural changes in the corpus callosum including axonal loss and/or demyelination. DW and MT imagings may be useful in detecting degeneration of the corpus callosum in AD.

Regional differences in diffusion abnormality in cerebral white matter lesions in patients with vascular dementia of the Binswanger type and Alzheimer's disease.

We investigated changes in water diffusion in the cerebral white matter of 14 patients with vascular dementia of the Binswanger type (VDBT) and ten patients with Alzheimer's disease (AD) with periventricular hyperintensity (PVH) lesions using diffusion-weighted magnetic resonance imaging (MRI) and studied the pathophysiological differences between white matter lesions found in these two conditions. Apparent diffusion coefficients (ADCs) in the anterior and posterior white matter and the genu and splenium of the corpus callosum were significantly higher in both groups of patients than in the 12 age-matched controls, and ADC values in VDBT and AD groups were almost the same. ADC ratios, defined as diffusion restricted perpendicular to the direction of nerve fibers, were also significantly higher in the patients than in the control subjects. However, there were regional differences in ADC ratios in the two conditions, with ratios in VDBT being higher in the anterior portions of the white matter but ratios in AD were higher in the posterior portions. The diffusion-weighted MRI technique may be useful in the differential diagnosis of VDBT and AD with white matter lesions.

[Magnetization transfer imaging of periventricular white matter lesions in patients with multi-infarct dementia].

Using magnetization transfer (MT) imaging, we studied the underlying pathological conditions of periventricular hyperintense (PVH) white matter changes seen on T2-weighted MR images of patients with multi-infarct dementia. Twenty-two patients with multiple lacunar infarcts and PVH lesions, including 11 with dementia (diagnosed as multi-infarct dementia) and 11 without dementia, and 10 control subjects (with multiple lacunes, but no PVH lesion) were studied using the MT technique. MT ratios (MTRs) were calculated for PVH lesions (normal-appearing frontal white matter in controls) and the genu of the corpus callosum. Signal intensities on T2-weighted images in PVH lesions of patients were significantly higher than those in normal-appearing white matter of controls, while there were no significant differences in signal intensity in the genu of the corpus callosum among the dementia, non-dementia and control groups. However, MTRs in patients with PVH lesions were significantly lower than those in controls, and MTRs in demented patients were significantly lower than those in non-demented patients. Moreover, MTRs in the genu of the corpus callosum of demented patients were significantly lower than in those in non-demented patients and controls. MTRs in PVH lesions and the genu of the corpus callosum significantly correlated with Hasegawa's dementia scale score. These results suggest that there is some difference in histopathologic changes of PVH lesions between demented and non-demented patients and that the pathological substrate in the corpus callosum may play a role in inducing cognitive decline. Studies with MT imaging may allow the characterization of different pathological conditions that cannot be visualized by conventional MRI.

Diffusion-weighted magnetic resonance and magnetization transfer imaging in the assessment of ischemic human stroke.

We compared characteristic features in ischemic stroke lesions from the hyperacute to the chronic stage on diffusion-weighted (DW) and magnetization transfer (MT) images with those on T2-weighted (T2W) images, and assessed changes in apparent diffusion coefficient (ADC), MT effect (MTe), and T2 ratios (infarct/normal) over time. DW images were particularly useful for detecting hyperacute infarcts within 6 hours of onset and in distinguishing acute lesions from chronic lesions. ADC ratios were lower within 7 days after onset and rose toward 1.0 in the subacute phase, becoming relatively isotense on ADC maps, but elevated thereafter. Although MTe ratios were unchanged or only subtly changed in the acute stage, they became significantly lower in the subacute and chronic stages. These combined magnetic resonance (MR) techniques were useful in the assessment of ischemic stroke and facilitated the determination of the age of cerebral infarct.

A decrease in cerebral cortex intensity on T2-weighted with ageing images of normal subjects.

To determine the change in intensity in the cerebral cortex on T2-weighted MRI with ageing, we reviewed the T2-weighted images of 83 normal subjects and measured the signal intensity in the cerebral cortex in 30 subjects randomly selected from them. Low-intensity areas were more common in the cerebral cortex of the aged. The intensity of different cortical regions varied, and the intensity in the temporal and parietal to be decreased with ageing. Presumably, this change of the intensity reflects senile changes, although low intensity is not evident in the temporal cortex because of its high basal intensity level.

Characteristic magnetic resonance imaging findings in Machado-Joseph disease.

OBJECTIVE: To clarify the characteristic magnetic resonance imaging (MRI) findings in patients with Machado-Joseph disease (MJD) diagnosed by genetic analysis. PATIENTS AND METHODS: Using MRI, we examined 31 patients genetically diagnosed as having MJD, 20 patients with sporadic olivopontocerebellar atrophy, and 26 control subjects. RESULTS: The MRIs of patients with MJD disclosed remarkably reduced width of the superior cerebellar peduncles, atrophy in the frontal and temporal lobes, diminished transverse diameter of the globus pallidus, and decreased anteroposterior and transverse diameters of the pons, which correlated with the width of the middle cerebellar peduncle. The width of the superior cerebellar peduncles also correlated with the diameter of the dentate or red nucleus in patients with MJD, but not in controls or in patients with sporadic olivopontocerebellar atrophy. On T2- and/or proton-weighted axial MR imaging, a high signal intensity in the transverse pontine fibers was observed in 14 (45.2%) of 31 patients with MJD and in all patients with sporadic olivopontocerebellar atrophy, but not in any controls. CONCLUSION: Affected afferent and efferent cerebellar tracts and atrophy of the frontal and temporal lobes and globus pallidus are characteristics of MRI of patients with MJD.

[Atrophy and magnetization transfer ratio of the corpus callosum in patients with Alzheimer's disease].

We compared atrophy and magnetization transfer ratio (MTR) in the corpus callosum in patients with Alzheimer's disease and age-matched normal subjects. Fifteen patients with Alzheimer's disease and fourteen normal subjects received MRI. The corpus callosum was divided into three parts (anterior, middle, and posterior portions) on midsagittal slice, and their areas on T2-weighted reversed images and MTR on magnetization transfer contrast images in each portion were measured. The area and MTR decreased significantly in the posterior portion in patients with Alzheimer's disease. In the anterior portion, MTR decreased significantly, but although the area showed no significant change. In the middle portion, the area and MTR showed no significant change. MTR and the area was correlated in each portion in patients with Alzheimer's disease. The score of Hasegawa dementia scale-revised (HDS-R) and the area of the middle, posterior and total of corpus callosum were significantly related. The score of HDS-R and MTR in the anterior portion of corpus callosum were significantly related. The present study revealed decreases in MTR in the anterior portion of the corpus callosum of patients with Alzheimer's disease although the area showed no significant change, and this change suggests the increase in free water and/or the decrease in bound water in tissues, probably due to demyelination and axonal degeneration.

Low intensity areas observed on T2-weighted magnetic resonance imaging of the cerebral cortex in various neurological diseases.

The cerebral cortex of patients with Alzheimer's disease (AD) or amyotrophic lateral sclerosis (ALS) may show low signal intensity on T2-weighted magnetic resonance images (MRI). Since these low intensity areas (LIA) are also often observed in aged patients with other diseases, we suspected that they might be a non-specific finding. We conducted a retrospective study of LIA in 139 patients with various diseases of the central and peripheral nervous systems, and evaluated their relationship to age and other MRI findings. Brain atrophy, ventricular dilatation, white matter lesions, and LIA were visually evaluated on axial images of the spin echo sequences obtained with a 1.5 tesla (T) system. We found that LIA appeared after age 50 and became more common with advancing age. Their presence correlated with brain atrophy and white matter lesions. They were most frequent in the motor cortex, followed by the occipital and sensory cortices. Their incidence in the motor cortex was significantly higher in patients with central nervous system diseases than in those with peripheral neuropathy. We conclude that LIA are common in old patients with various neurological diseases and suggest that the deposition of iron in the cerebral cortices causes their development.

[The effect of age and disease on the MR imaging T2 low signal intensity area in the cerebral cortex].

We retrospectively studied magnetic resonance (MR) images of the brain in 139 patients (16 cases of Alzheimer's disease, 8 cases of Parkinson's disease, 53 cases of multiple cerebral infarct, 33 cases of other central nervous diseases, and 29 cases of peripheral neuropathy) between the age of 6 and 85 years old with a mean age of 60.6 +/- 18.5 to examine the appearance of T2 low signal intensity areas (T2CLIA) in the cerebral cortex. Motor, occipital, sensory or other cortices were evaluated with long repetition time/echo time (TR/TE) spin-echo sequences and staged into three grades in the motor cortex: none, partial, and whole; and two grades in the others: none or present. In general, T2CLIA was not seen in any cortex in patients less than 50 years old, then after 50 years old T2CLIA increased with age. Over 70 years of age T2CLIA appeared in 50.9% of patients in the whole motor cortex, 88.7% in either whole or partial motor cortex, 47.2% in the occipital cortex, and 20.8% in the sensory cortex. T2CLIA was not observed in other cortices. The incidence of T2CLIA appearance in the motor cortex was significantly higher in all central nervous diseases than in cases of peripheral neuropathy over 70. T2-CLIA showed a correlation with temporal lobe atrophy and white matter lesions in the motor cortex. In the sensory cortex, T2CLIA correlated with white matter lesions. These results suggest that T2-CLIA may correlate with age or accumulation of nonheme iron in the cortex associated with central nervous diseases.