What are the MRI characteristics of oxyhemoglobin in intracranial hemorrhage within the first 24 hours, focusing on red blood cell integrity and T1/T2 signal changes?

In the hyperacute phase of intracranial hemorrhage (less than 1 day), oxyhemoglobin is present with intact red blood cells. On MRI, this appears as T1 iso/dark and T2 bright. Key diagnostic features include the absence of mass effect and the potential for subtle T1 signal changes. Clinical pearls: Early recognition is crucial for management, and understanding the evolution of hemorrhage on MRI is essential. Common pitfalls include mistaking hyperacute hemorrhage for other T2-bright lesions such as edema or tumor.