Magnetic resonance spectroscopy in the diagnostic evaluation of brainstem lesions in Alexander disease

Alexander disease is a progressive neurodegenerative disease, which can present with brainstem lesions with imaging characteristics similar to multifocal low-grade glioma, thus presenting a diagnostic dilemma. The authors report a 6-year-old child presenting with multifocal brainstem lesions subsequently diagnosed to have Alexander disease. In vivo magnetic resonance spectroscopy generated a metabolite profile of the lesion allowing differentiation from low-grade glioma. Magnetic resonance spectroscopy is a powerful tool in the assessment of brainstem lesions and is a useful adjunct to conventional magnetic resonance imaging in the assessment and diagnosis of atypical brain lesions.     

Magnetic resonance angiography of carotid and cerebral arterial occlusion in rats using a clinical scanner

In rat models to induce both focal cerebral ischemia and chronic cerebral hypoperfusion, it is highly desirable to verify the success of vessel occlusion and reopening with non-invasive method. The contrast-agent free 3D time-of-flight magnetic resonance angiography (TOF-MRA), diffusion-weighted imaging (DWI) and T2-weighted imaging by 3.0-T MR clinical scanner were applied when unilateral middle cerebral artery (MCA) was occluded and reopened, and after bilateral common carotid arteries were in ligation. The arterial angiograms of the rat brain and neck were achieved successfully in all chosen directions by the 3D TOF-MRA. It was shown that MCA in occlusion presented no signal in MRA, and the parenchyma of the ipsilateral MCA territory hypointensity signal in maps of apparent diffusion coefficient (ADC). After reperfusion, the signal intensity of ipsilateral MCA was resumed in MRA, and the decreased ADC was restored simultaneously. However, after 5h of reperfusion, it was found that the value of ADC deteriorated second time with high T2 value. In bilateral common carotid artery occlusion (BCCAO) rats, it can be confirmed by MRA that the effectively occluded BCCA presented the absent signal and the basilar artery became tortuous. As a result, MRA by clinical scanner was proved of a valuable method to validate transient middle cerebral artery occlusion (MCAO) and permanent BCCAO rat model.     

Magnetic resonance angiography in a patient with Crohn's disease associated cerebral vasculitis

Vasculitits of the central nervous system (CNS) is a known complication of chronic inflammatory bowel diseases. We report the case of a female patient with Crohn's disease, developing vasculitis of the CNS with evidence of pathological vessel depiction on magnetic resonance angiography. To our knowledge this is the first case report regarding MRA documentation of vessel changes typical for angiitis in a patient with Crohn-associated vasculitis of the CNS.     

Magnetic resonance imaging of cerebral microbleeds

Magnetic resonance imaging of patients with primary intracerebral haemorrhage has drawn attention to focal areas of signal loss, which were suggested to indicate hemosiderin deposition from earlier bleeds. Correlative histopathologic data have recently confirmed this assumption and support a strong association between the occurrence of microbleeds and various types of small vessel disease, such as hypertensive lipofibrohyalinosis and cerebral amyloid angiopathy. Therefore, microbleeds that are detectable by magnetic resonance imaging could be viewed as markers for vessel wall disorders with a higher tendency for intracerebral bleeding. This finding appears to be of diagnostic importance, but could also help to predict a patient's risk for spontaneous rebleeding or bleeding complications after anticoagulation.     

Magnetic resonance perfusion imaging of resting-state cerebral blood flow in preclinical Huntington's disease

Magnetic resonance imaging (MRI) of the brain could be a powerful tool for discovering early biomarkers in clinically presymptomatic carriers of the Huntington''s disease gene mutation (preHD). The aim of this study was to investigate the sensitivity of resting-state perfusion MRI in preHD and to identify neural changes, which could serve as biomarkers for future clinical trials. Differences in regional cerebral blood flow (rCBF) in 18 preHD and 18 controls were assessed with a novel MRI method based on perfusion images obtained with continuous arterial spin labeling. High-resolution structural data were collected to test for changes of brain volume. Compared with controls, preHD individuals showed decreased rCBF in medial and lateral prefrontal regions and increased rCBF in the precuneus. PreHD near to symptom onset additionally showed decreased rCBF in the putamen and increased rCBF in the hippocampus. Network analyses revealed an abnormal lateral prefrontal pattern in preHD far and near to motor onset. These data suggest early changes of frontostriatal baseline perfusion in preHD independent of substantial reductions of gray matter volume. This study also shows the feasibility of detecting neural changes in preHD with a robust MRI technique that would be suitable for longitudinal multisite application.     

Magnetic resonance spectroscopy in cerebral ischemia.

Magnetic resonance spectroscopy (MRS) has been a fundamental and invaluable tool in the fields of chemistry and physics for over 40 years and has only been applied directly to the field of medicine in the last decade. MRS has contributed significant information on ischemic brain metabolism in the clinical patient. The potential of spectroscopy now extends to the diagnostic monitoring of metabolic change, in identifying markers of a therapeutic window, and establishing prognosis and outcome. This article presents a review of MRS studies of cerebral ischemia in clinical patients.     

Magnetic resonance angiography of experimental cerebral vasospasm

The purpose of this study was to observe spastic cerebral arteries by magnetic resonance angiography (MRA) and to establish acetazolamide reactivity of these vessels. After control studies using MRA and conventional angiography, subarachnoid haemorrhage (SAH) was induced on day 0 in 7 Japanese monkeys. MRA and conventional angiography were then repeated on day 7 to observe the development of cerebral vasospasm. Reactivity of cerebral vessels to acetazolamide was also studied in both control animals (angiography before SAH) and on day 7 after SAH. Cerebral vasospasm was detected by both conventional angiography and MRA on day 7. The arteries on the side of the clot were more spastic than those on the control side. MRA was superior to conventional angiography in demonstrating dilatation of both control arteries (before SAH induction) and vasospastic arteries (on day 7 after SAH) after administration of acetazolamide.     

Magnetic resonance imaging in the evaluation of intracranial hemorrhage

Magnetic resonance imaging is emerging as a valuable tool for the urgent evaluation of patients with acute stroke. This review focuses on the applications of magnetic resonance imaging in the diagnosis and management of intracranial hemorrhage. The biophysical properties of blood in the neuroaxis and the magnetic resonance imaging evolution of intracranial bleeding are reviewed. The potential applications of magnetic resonance imaging in the evaluation and therapy of specific types of intracranial hemorrhage are discussed. Emphasis is made on the superiority of magnetic resonance imaging in detecting intracranial hemorrhage and ischemic stroke. Although there is some hesitation to perform magnetic resonance imaging to evaluate acute intracranial hemorrhage, there is strong evidence that magnetic resonance imaging is not inferior to computerized tomography in this clinical setting. In the era of acute stroke intervention, magnetic resonance imaging offers significant advantages over computed tomography.     

Magnetic resonance perfusion imaging evaluation in perfusion abnormalities of the cerebellum after supratentorial unilateral hyperacute cerebral infarction

Magnetic resonance imaging (MRI) data of 10 patients with hyperacute cerebral infarction (≤6 hours) were retrospectively analyzed.Six patients exhibited perfusion defects on negative enhancement integral maps,four patients exhibited perfusion differences in pseudo-color on mean time to enhance maps,and three patients exhibited perfusion differences in pseudo-color on time to minimum maps.Dynamic susceptibility contrast-enhanced perfusion weighted imaging revealed a significant increase in region negative enhancement integral in the affected hemisphere of patients with cerebral infarction.The results suggest that dynamic susceptibility contrast-enhanced perfusion weighted imaging can clearly detect perfusion abnormalities in the cerebellum after unilateral hyperacute cerebral infarction.     

Magnetic resonance angiography in moyamoya disease

Spontaneous occlusion of the circle of Willis, i.e., moyamoya disease (MMD), is a clinical disease entity angiographically characterized by progressive and bilateral stenosis of the carotid bifurcation, with a hazy collateral network at the base or convexity of the brain. Although the importance of computed tomography (CT) and conventional magnetic resonance (MR) imaging in diagnosing MMD has already been determined, conventional arteriography is still regarded as necessary for definitive diagnosis. Magnetic resonance angiography (MR-A) is a very recent vascular imaging technique which allows noninvasive and direct imaging of vessels without the use of contrast medium. We present four pediatric cases of MMD, evaluated by conventional angiography, CT, MR imaging, and MR-A. Our data demonstrate thatMR-A is successful both in allowing detection of occlusive disease of the basal portion of the internal carotid artery and large branch basal cerebral vessels and demonstrating the collateral vessels at the base of the brain. As a noninvasive procedure, MR-A promises to become a valuable alternative to classical angiography in the diagnosis of MMD.     

Magnetic resonance imaging in Pelizaeus-Merzbacher disease

Cranial computed tomography of a boy with clinical characteristics of the classic form of Pelizaeus-Merzbacher disease did not reveal a notable abnormality other than enlarged ventricles. Magnetic resonance imaging, however, demonstrated diffuse changes in the white matter with sparing of scattered small areas, suggesting persistent myelin islands which are a typical neuropathologic finding in Pelizaeus-Merzbacher disease. Magnetic resonance imaging appears more useful than computed tomography in confirming the diagnosis of Pelizaeus-Merzbacher disease.     

Magnetic resonance relaxometry in Parkinson's disease

Neurological Sciences - A central role of iron in the pathogenesis of idiopathic Parkinson's disease (PD), due to its increase in substantia nigra pars compacta dopaminergic neurons and its...     

Magnetic resonance imaging in moyamoya disease

Magnetic resonance imaging of the brain in a patient with moyamoya disease demonstrated multiple scattered white matter lesions, but was not sufficiently specific to confirm the diagnosis without other techniques.     

Magnetic resonance spectroscopy in cerebral ischemia and infarction

Proton magnetic resonance spectroscopy (MRS) and spectroscopic imaging (MRSI) are promising techniques for the noninvasive investigation of brain metabolism in vivo. They can be implemented routinely on most clinical scanners, and typically have a spatial resolution of approximately 1 to 10 cm³ with scan times of 5 to 20 minutes. Various compounds can be detected in proton MRS of the brain. Compounds that are of particular importance in cerebrovascular disease are lactate (as a marker of ischemia) and N-acetyl aspartate (NAA), which is believed to be primarily of neuronal/axonal origin. The time-course of the changes in these compounds during ischemia is blood-flow dependent and potentially could be used to stratify acute stroke patients into different treatment protocols and to monitor the effects of treatment. However, many technical challenges have to be overcome (in particular, the development of fast MRSI techniques to reduce scan times) before this goal is realized. Also, more research is required to understand the significance of spectral changes during ischemia, and to compare the relative value of MRSI with other emerging MRI techniques, such as diffusion- and perfusion-weighted MRI.     

Magnetic resonance imaging in Parkinson's disease

Magnetic resonance imaging was utilized to examine changes in the pars compacta associated with Parkinson's disease. We found a reduction in average width of the pars compacta in advanced- but not early-stage patients. Conversely, a significant difference in width (right minus left) was observed in early- but not late-stage patients. Width asymmetry may be a sensitive magnetic resonance imaging indicator for the early detection of Parkinson's disease when there is a predominance of unilateral clinical symptoms.     

Magnetic resonance imaging in diplegic form of cerebral palsy

Eighteen children with diplegic form of cerebral palsy (CP) underwent magnetic resonance imaging (MRI) because of the enlarged occipital horns of both lateral ventricles found on previous computerized tomography (CT). In 16 of them squint was present. MRI in flow attenuated inversion recovery (FLAIR) and turbo spin echo (TSE) modes (T2 weighted images) best showed white matter lesions in occipital areas in all patients with squint, while no white matter changes could be detected in CT (in retrospect), thus proving the superiority of MRI in examining CP children. The authors postulate that the hemispheric occipital lesion causing impairment of visual co-ordination may result in squint.     

Magnetic resonance imaging of the midbrain in Parkinson's disease

We have analyzed magnetic resonance images of the midbrain in patients with Parkinson's disease, and have found that there is a narrowing of the signal from the pars compacta of the substantia nigra relative to controls. The nature of the histological changes that may be responsible for this effect is discussed. Magnetic resonance imaging has the potential of becoming a useful diagnostic tool in the management of parkinsonism.