Abstract
Acute ischemic stroke commonly presents as hypodensity on computed tomography (CT), and as high diffusion-weighted magnetic resonance imaging (DWI) signal and low apparent diffusion coefficient (ADC) signal on MRI. However, the radiographic characters of the infarct with hyperacute recanalization have received little attention. This paper reports a case of an ischemic stroke patient with middle cerebral artery (MCA) occlusion and hyperacute spontaneous recanalization. A series of radiological exams were applied for dynamic observation of the infarct regions. CT showed a high hyperdense sign at the second segment of MCA and various kinds of images of infarcted lenticula in several phases, namely hypodensity at the third hour from onset, increased density at the fourth hour, significant hyperdensity on the seventh day and equal density on the fourteenth day. MRI showed a slightly low DWI signal and a high ADC signal in both the infarcted lenticula and caudate at the twelfth hour. The underlying mechanisms for explaining the evolution of infarct images are discussed in this article. Both ischemic injury and reperfusion affect the process of cerebral edema resulting from ischemia, and subsequently contribute to the imaging of ischemic stroke on CT and MRI scans. Reperfusion promotes the development of cerebral edema and also accelerates the evolution of infarct images. Consequently, acute ischemic stroke could manifest as hyperdensity on CT, and slightly lower DWI signal and higher ADC signal on MRI in case of recanalization.