PATIENT CHARACTERISTICS: Age: 18 to 79 Sex: Women Performance status: Not specified Life expectancy: Not specified Hematopoietic: Not specified Hepatic: Not specified Renal: Not specified Cardiovascular: No implanted pacemaker Other: No implanted ferromagnetic device No ferromagnetic aneurysm clip No severe claustrophobia No ocular metal fragments No schrapnel injury No difficulty lying prone No poor venous access No impaired decision-making abilities Not pregnant