Safe for someone who has shunt for normal pressure hydrocephalus to get brain mri for suspected pituitary adenoma? if no, is cat scan used instead?

Check with neurosurg: Check with the neurosurgeon as to the type of shunt in place. With normal pressure hydrocephalus, it is very common that the shunt is a programmable shunt that allows the neurosurgeon to change the amount of drainage with a special magnet. There are some that are MRI resistant and some that aren't(these need reprogramming soon after mri). If it is non-programmable, you don't need to adjust it.