Nuclear magnetic resonance imaging in patients with stroke.

In contrast to CT, NMR imaging revealed a high percentage of abnormalities in the TIA-RIND population studied. The various patterns of abnormalities identified should provide further insight into the pathophysiology of ischemic cerebrovascular disease. Age and hypertension appeared to be the most significant clinical risk factors for TIA-RIND. Although periventricular hypodensities have been visualized by CT for many years, their clinical significance has only recently been appreciated. NMR shows the same periventricular changes as increased signal (long T2), but shows it in a more dramatic fashion. These periventricular abnormalities, seen both by CT and NMR, have been shown in some cases to be compatible with the pathologic diagnosis of SAE, or Binswanger's disease. Watershed abnormalities both with and without corresponding cerebral infarctions have been presented. At present, this appears to be a ubiquitous group of cerebrovascular disease with multiple underlying causes. NMR is superior to CT for demonstrating watershed infarctions, not only because it reveals ones missed by CT, but also because it shows a fuller extent of involvement than does CT. The evolution of cerebral infarctions as seen by CT and NMR has been presented. NMR demonstrates abnormalities earlier than CT. The region of infarction appears more extensive than by CT and chronic infarctions show an associated rim of prolonged T2 that may correspond to the ischemic penumbra or regions of ischemic demyelinization. CT phenomena, such as fogging and GME, have their NMR correlates. To date, all regions of GME shown by CT have also been demonstrated by NMR. Cortical infarctions, thought in many instances to be due to emboli have been frequently demonstrated by NMR. NMR imaging is clearly superior to CT for recognizing these lesions because it is not hampered by artifact from bone adjacent to cortex, as is CT. Similarly, posterior fossa and brainstem infarctions may be seen to advantage by NMR.