Is it safe to get an mri of the pituitary with & without contrast while on your period and is fasting required? if so for how many hours at least? will menstruation raise the risk of an allergic reaction from the contrast? thanks?

During your period is no problem to do the MRI and your period does not affect the risk of an allergic reaction. During your cycle, hormonal changes may influence drug absorption, distribution, metabolism or excretion; however, there is no clear pattern of the slight ways drugs are affected. Menstruation is not a reason to not do a procedure or a test in medicine typically.