What condition is characterized by very low T1 and T2 marrow signal on MRI, often associated with splenomegaly and extramedullary hematopoiesis?

Myelofibrosis is characterized by very low T1 and T2 marrow signal due to increased collagen deposition and fibrosis. Key diagnostic features include splenomegaly, extramedullary hematopoiesis, and leukoerythroblastosis on peripheral blood smear. Common pitfalls include mistaking it for other marrow-replacing processes such as metastatic disease or osteopetrosis. MRI can help differentiate these conditions based on signal characteristics and clinical context.