MR pattern of hyperacute cerebral hemorrhage

Neural substrates of subcortical aphasia in subacute stroke: Voxel-based lesion symptom mapping study

Subcortical aphasia develops as a result of damage to subcortical brain areas without loss of cortical functions. Although earlier voxel-based lesion-symptom mapping (VLSM) studies have shown possible neural correlates for aphasia, it remains to be clarified which brain regions are associated with subcortical aphasia. The aim of this study was to investigate the neural substrates associated with subcortical aphasia in patients with stroke using VLSM and atlas-based analyses to explore the involvement of white matter tracts and subcortical structures. Fifty patients with subacute subcortical stroke without cortical involvement were retrospectively enrolled: 24 with and 26 without aphasia. We performed VLSM and atlas-based analyses of the patients' fluid-attenuated inversion recovery images and found that the left perisylvian white matter, left fronto-occipital fasciculus, uncinate fasciculus, and forceps minor were significantly more greatly affected in the aphasia than in the non-aphasia group. The left anterior thalamic radiation, cingulum (cingulate gyrus), and superior longitudinal fasciculus also showed higher involvement in this group (marginal significance). Among the subcortical regions, the left caudate and putamen were more greatly involved in the aphasia group. Our findings confirm language processing as one of the integrated sensory-motor processes that occur in the region around the left sylvian fissure. Our atlas-based analysis approach can be used to complement VLSM analyses.

The use of diffusion weighted imaging to evaluate pathology outside the brain parenchyma in neuroimaging studies

Diffusion-weighted imaging (DWI) has transformed the radiological assessment of a variety of cerebral pathologies, in particular acute stroke. In neuroimaging studies, DWI can also be used to evaluate pathology outside the brain parenchyma, although it is sometimes underutilized for this purpose. In this pictorial review, the principles of DWI are outlined, and 13 cases of abnormal diffusion outside the brain parenchyma are illustrated in order to show DWI as a useful sequence for the evaluation of the following recommended review areas: the dural venous sinuses, internal carotid arteries, meninges, ventricles, cavernous sinus and orbits, skull base and lymph nodes.

Hemorrhagic cerebrovascular disease

Primary or nontraumatic spontaneous intracerebral hemorrhage (ICH) accounts for 10-15% of all strokes, and has a poor prognosis. ICH has a mortality rate of almost 50% when associated with intraventricular hemorrhage within the first month, and 80% rate of dependency at 6 months from onset. Neuroimaging is critical in identifying the underlying etiology and thus assisting in the important therapeutic decisions. There are several imaging modalities available in the workup of patients who present with ICH, including computed tomography (CT), magnetic resonance imaging (MRI), and digital subtraction angiography (DSA). A review of the current imaging approach, as well as a differential diagnosis of etiologies and imaging manifestations of primary versus secondary intraparenchymal hemorrhage, is presented. Active bleeding occurs in the first hours after symptom onset, with early neurologic deterioration. Identifying those patients who are more likely to have hematoma expansion is an active area of research, and there are many ongoing therapeutic trials targeting this specific patient population at risk.

Imaging of hemorrhagic stroke

Neuroimaging by CT or MR is necessary for the detection of hemorrhagic stroke and provides important data regarding the cause of stroke. Serial changes in the CT and MR appearance of hematoma attributable to temporal evolution must be assessed to assure accurate diagnosis. Emerging evidence suggests that the use of MR imaging alone may be adequate for identifying hemorrhage in acute stroke patients and that GRE MR imaging is superior to both CT and conventional spin-echo MR imaging sequences for the detection of chronic microbleeds and hemorrhagic conversion of infarction.

Hemorrhagic stroke

Neuroimaging by CT or MR imaging is necessary for the identification of hemorrhagic stroke and provides information about its cause. The appearance of intracranial hematoma (ICH) on CT and MR imaging evolves over time and must be understood to facilitate accurate diagnosis. The cause of ICH varies by location. New evidence suggests that MR imaging alone may be adequate to identify hemorrhagic stroke in the acute setting, and that MR imaging is superior to CT for identification of chronic microbleeds and hemorrhagic conversion of infarction.