What is the typical time course and pattern of contrast enhancement on CT in a brain infarct, and what are the key features to differentiate it from other pathologies?

Contrast enhancement in a brain infarct typically begins around 1 week post-infarction, peaks between 7 to 14 days, and often displays a gyral pattern. As gliosis occurs and the blood-brain barrier is repaired, enhancement diminishes and usually resolves by 3 months. Key diagnostic features include the gyral pattern of enhancement and the temporal progression. Clinical pearls include recognizing that early enhancement may be subtle and differentiating it from conditions like tumors or infections, which may have more irregular or nodular enhancement patterns. A common pitfall is mistaking early enhancement for hemorrhagic transformation; careful correlation with clinical history and other imaging findings is essential.