Evolution of MR contrast enhancement patterns during the first week after acute ischemic stroke

BACKGROUND AND PURPOSE: Intravascular and parenchymal enhancement have been detected with contrast-enhanced T1-weighted MR imaging in patients with is chemic stroke. Diffusion-weighted MR imaging depicts infarct within minutes after the onset of symptoms. The aims of this study were to study the diff erent MR enhancement findings during the first week after stroke and to asc ertain whether the presence of intravascular enhancement over a larger area than the infarct on diffusion-weighted images on day 1 is able to predict substantial infarct growth during the first week. METHODS: Forty-eight patients were imaged on the first and second days and again 1 week after the onset of ischemic stroke. T1-weighted spin-echo imag ing was performed before and after a 0.2 mmol/kg bolus of gadolinium chelat e, Diffusion-weighted imaging was performed at the same slice positions. En hancement findings were categorized as intravascular and parenchymal, with further categorization of parenchymal enhancement as cortical, subcortical, and deep; these findings were then compared with diffusion-weighted imagin g findings. RESULTS: Intravascular enhancement in the infarcted area was detected on da y 1 in 78% of the cases, on day 2 in 78% of the cases, and at 1 week in 30% of the cases. Parenchymal enhancement was detected in 26%, 56%, and 100% o f the cases, respectively. Intravascular enhancement over a larger area tha n the infarct on diffusion-weighted images on day 1 was not associated with the extent of infarct growth, CONCLUSION: Detection of different patterns of contrast enhancement can hel p in determining the age of infarct, Parenchymal enhancement may be intense and can cause diagnostic uncertainty in cases in which the clinical histor y is obscure.