Ultrasound etc showed cyst on my R Ovary, 5.3 cm, CT scan results (non specific presacral mass) What does this mean? Nurse said MRI will be scheduled

Ovaries can enlarge. for a number of reasons. Some of them can be benign (like a cyst), but some are more serious, unfortunately. Without seeing your images, we can't provide a diagnosis. Your doctor has ordered MRI because US and CT did not allow the radiologist to confidently tell benign from disease. If you would like a second opinion on your studies, you can reach me at healthtap.com/saurbornmd.
Ultrasound. is good at picking up cysts. Likely CT SHOWS THE SAME THING just not able to characterize mass. If you want a clarification, mri will likely do that.