Flávio Túlio Braga

Comparison of magnetic resonance imaging sequences with computed tomography to detect low-grade subarachnoid hemorrhage: Role of fluid-attenuated inversion recovery sequence.

Objectives: To compare computed tomography (CT) with magnetic resonance imaging (MRI) for the presumptive diagnosis and localization of acute and subacute low-grade subarachnoid hemorrhage (SAH). Methods: We consecutively enrolled 45 patients clinically suspected of low-grade SAH, comparing them with a control group. We obtained axial nonenhanced CT scans as well as fluid-attenuated inversion recovery (FLAIR) and T2-weighted gradient echo (T2*) MRI sequences at 1.0 T. Two neuroradiologists scrutinized the presence of blood at 26 different regions in the intracranial subarachnoid space (SAS). Results: Three of 45 patients had normal CT and MRI scans, and SAH was excluded by lumbar puncture. We demonstrated SAH on CT scans in 28 of 42 (66.6%) patients, T2* sequences in 15 of 42 (35.7%) patients, and FLAIR sequences in 42 of 42 (100%) patients. Fluid-attenuated inversion recovery sequences were superior to CT in 16 of the 26 evaluated regions. Conclusions: The FLAIR sequence was superior for presumptive diagnosis and localization of acute and subacute low-grade SAH, representing a potential tool in this setting.

Focal transient lesion in the splenium of the corpus callosum in three non-epileptic patients.

IntroductionWe analyzed the imaging features of transient focal lesions in the splenium of the corpus callosum (SCC) in non-epileptic patients receiving antiepileptic drugs (AEDs).MethodsWe identified signal abnormalities in the SCC in three non-epileptic patients, all of them receiving AEDs. We examined two of these patients with multiplanar magnetic resonance (MR) imaging using 1.0-T equipment including fluid-attenuated inversion recovery (FLAIR), T2-weighted (TSE) and T1-weighted (SE) sequences before and after injection of contrast agent. The third patient was studied using 1.5-T equipment with the same sequences. Additionally, a T1 SE sequence with a magnetization transfer contrast pulse off resonance (T1 SE/MTC), diffusion-weighted imaging (EPI-DWI) and apparent diffusion coefficient (ADC) maps were obtained.ResultsWe observed an identical pattern of imaging abnormalities in all patients characterized by round lesions, hyperintense on FLAIR and hypointense on T1 SE images, located in the central portion of the SCC. One lesion showed homogeneous gadolinium enhancement and perilesional vasogenic edema. This particular lesion showed restricted diffusion confirmed on the ADC map. This pattern was considered consistent with focal demyelination. Follow-up MR examinations showed complete disappearance or a clear reduction in lesion size. All patients had been treated with AEDs, but they did not show any clinical signs of toxicity, interhemispheric symptoms, or abnormal neurological findings (including seizures).ConclusionWe believe that our MR findings might be interpreted as transient lesions related to AED toxicity. They presumably resulted from focal demyelination in the central portion of the SCC.

Lactate Detection by MRS in Mitochondrial Encephalopathy: Optimization of Technical Parameters

Mitochondriopathies are a heterogeneous group of diseases with variable phenotypic presentation, which can range from subclinical to lethal forms. They are related either to DNA mutations or nuclear‐encoded mitochondrial genes that affect the integrity and function of these organelles, compromising adenosine triphosphate (ATP) synthesis. Magnetic resonance (MR) is the most important imaging technique to detect structural and metabolic brain abnormalities in mitochondriopathies, although in some cases these studies may present normal results, or the identified brain abnormalities may be nonspecific. Magnetic resonance spectroscopy (MRS) enables the detection of high cerebral lactate levels, even when the brain has normal appearance by conventional MR scans. MRS is a useful tool for the diagnosis of mitochondriopathies, but must be correlated with clinical, neurophysiological, biochemical, histological, and molecular data to corroborate the diagnosis. Our aim is to clarify the most relevant issues related to the use of MRS in order to optimize its technical parameters, improving its use in the diagnosis of mitochondriopathies, which is often a challenge.

Pyramidal tract degeneration in multiple system atrophy: the relevance of magnetization transfer imaging.

The clinical features of multiple system atrophy (MSA) include four domains: autonomic failure/urinary dysfunction, Parkinsonism, cerebellar ataxia, and corticospinal tract dysfunction. Although the diagnosis of definite MSA requires pathological confirmation, magnetic resonance imaging (MRI) studies have been shown to contribute to the diagnosis of MSA. Although pyramidal tract dysfunction is frequent in MSA patients, signs of pyramidal tract involvement are controversially demonstrated by MRI. We evaluated the pyramidal involvement in 10 patients (7 women) with clinically probable MSA, detecting the presence of spasticity, hyperreflexia, and Babinski sign, as well as demonstrating degeneration of the pyramidal tract and primary motor cortex by MRI in all of them. Our article also discusses key radiological features of this syndrome. In MSA, pyramidal tract involvement seems to be more frequent than previously thought, and the clinicoradiological correlation between pyramidal tract dysfunction and degeneration may contribute to the understanding of the clinical hallmarks of MSA. MRI may also add information regarding the differential diagnosis of this syndrome.

Intralabyrinthine hemorrhage associated with superficial siderosis of the central nervous system.

Sudden sensorineural hearing loss caused by intralabyrinthine hemorrhage is a rare entity reported in patients with coagulopathy, anticoagulant therapy, trauma, labyrinthitis, leukemia, cocaine consumption, systemic lupus erythematosus, and local hemorrhagic pathologies (1). Intralabyrinthine hemorrhage is probably an underdiagnosed condition that, before the advent of magnetic resonance imaging (MRI), had been described in the literature only after postmortem evaluation. Magnetic resonance imaging demonstrates intralabyrinthine hyperintensities on spin echo T1-weighted (T1 SE) images, consistent with either methemoglobin content from hemorrhage or elevated protein levels (Fig. 1). Persistent intralabyrinthine hyperintensities on fat-saturated T1weighted images exclude the possibility of a lipoma. Superficial siderosis of the central nervous system (CNS) is a rare cause of sensorineural hearing loss secondary to recurrent low-grade subarachnoid hemorrhage. As time goes by, the hemorrhage leads to hemosiderin deposition in the subpial layer of the brain and spinal cord. The most common neurological manifestations include sensorineural hearing loss and ataxia. The chronic and recurrent low-grade subarachnoid hemorrhage is crucial to the development of superficial siderosis because

Asymmetric cortical degenerative syndromes: an integrated approach to clinical and imaging review.

Background:The term asymmetric cortical degenerative syndromes (ACDSs) refers to any brain afflictions that result in selective atrophy, particularly with an asymmetric pattern. Regardless of the etiology, the resulting compromised profile reflects the affected topography, which correlates with the clinical findings, more than any specific neuropathologic entity. Review Summary:ACDS can represent a diagnostic challenge, because of an overlap of clinical manifestations, especially in the early stages. Magnetic resonance techniques are useful to understand nuclear medicine studies and to confirm areas of focal atrophy by providing anatomic details and allowing an accurate correlation with several different clinical settings. Conclusions:This article demonstrates a practical neuroradiologic approach for ACDS, including optimized imaging analysis (magnetic resonance and nuclear medicine studies), which correlates their patterns with clinical and pathologic findings of the most relevant disorders.