[CT and MRI: what you see and don't see].

CT and MRI have become indispensable methods for the diagnosis of stroke or the investigation for the disease. The use of these auxiliary diagnostic procedures, especially of MRI, has made possible the accurate diagnosis of lesions of the posterior cranial fossa. The flow void in MRI has made it feasible to infer severe stenosis or occlusion of the main arteries before undertaking angiography. The silent stroke or white matter abnormalities in the vicinity of the lateral ventricle observed in CT or MRI have become a serious clinical problem and these are generally considered risk factors for stroke. Obviously, CT and MRI have proven effective in this area, yet their findings do not always make it readily possible to infer the nature of cerebral arteries involved. Recently, here have been attempts to classify infarcts in the region of perforating branches of the middle cerebral artery. With the diversification of therapeutic approaches for stroke in the days to come, the effort to encourage such insight on the basis of non-invasive testing will be increasingly important.