Journal of neuroimaging : official journal of the American Society of Neuroimaging
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High-intensity transient signals (HITS) are frequently detected by transcranial Doppler (TCD) ultrasound in patients with mechanical prosthetic heart valves (PHVs), but published data about their clinical relevance are controversial. This study was undertaken to determine the clinical relevance of HITS in patients with mechanical PHVs. ⋯ Only age was a significant predictor of HITS in patients with mechanical PHVs. The lack of association between HITS, clinical symptoms, and cognitive functioning suggests that most of these signals represent harmless epiphenomena, and only HITS detected after O2 inhalation have any clinical relevance.
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Despite good clinical criteria for diagnosing optic neuritis (ON), only a few techniques can precisely assess its impact on visual brain function. The authors studied whether functional magnetic resonance imaging (fMRI) of visual activation reliably reflects the cerebral consequences of acute unilateral ON, and how fMRI correlates with clinical function and visual evoked potentials (VEPs). Twenty ON patients, before and after steroid treatment, were compared to 20 controls. ⋯ The higher stimulation frequencies yielded greater fMRI responses from unaffected eyes, but not from affected eyes, in controls. The fMRI responses were quantifiable in every subject, whereas in 11 ON eyes, no VEPs were obtained during the acute stage. The authors conclude that fMRI is sensitive to the cerebral response alteration during ON and might therefore contribute to evaluating the temporal evolution of the visual functional deficit during recovery or therapy.
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Case Reports
Development of a posterior fossa cavernous malformation associated with bilateral venous anomalies: case report.
Venous angiomas (VAs) and cavernous malformations (CMs) are common cerebrovascular malformations. Frequently, these lesions are found in close proximity. The interrelationship between VAs and CMs has not yet been adequately defined. ⋯ The sequential imaging suggests a causal relationship between VAs and some CMs. Furthermore, the detailed MRI permitted radiosurgical treatment of these CMs. The occurrence of de novo CMs adjacent to VAs on future imaging studies in other patients may help confirm the etiology of at least a subset of CMs.
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The diagnosis of preclinical Alzheimer's disease (AD) (or mild cognitive impairment [MCI]) is loaded with a high degree of uncertainty. The aim was to test the accuracy of a computed tomography-based (CT-based) marker of medial temporal lobe atrophy, the radial width of the temporal horn (rWTH), in MCI. ⋯ The rWTH is a measure sensitive to the regional brain atrophy common in early AD.
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The purpose of this study was to reevaluate the usefulness of relative maximum signal drop (rMSD), as compared to relative cerebral blood volume (rCBV) and cerebral blood flow (rCBF), in dynamic susceptibility contrast magnetic resonance imaging (MRI). ⋯ The authors conclude that rMSD is as useful as rCBF under a variety of pathophysiological conditions, whereas in conditions with normal mean transit time, such as brain tumors, rMSD provides equivalent blood volume information to rCBV. The simplicity of rMSD maps could lead to the increased use of perfusion-weighted MRI.