When is follow-up imaging recommended to differentiate between a small brain neoplasm and a small infarct, and what changes in lesion size should be expected?

Follow-up imaging is recommended at 3 weeks post-initial scan. By this time, virtually all infarcts will have decreased in size due to resolution of edema and tissue necrosis. If the lesion remains the same size or has increased, a neoplasm should be considered. Key diagnostic features include the presence of mass effect, enhancement patterns, and diffusion characteristics. Be aware of mimickers such as resolving hematomas or demyelinating lesions, which can complicate diagnosis.