Ultrasound vs MRI accuracy

My wife started to experience some pain before menses about 6 mo ago. Some clots were coming during the periods. The visit to gynecologist did not raise any concern. About 6 weeks ago she had very strong abnominal pain. After that she went through two ultrasounds and MRI. Both ultrasounds did show enlargement of right ovary (about 5.5 by 5.5 cm by 3.5) and suggested dermoid, though MRI DID NOT suggest any enlargement or tumor, but indicated small multiple cysts on right and hemmorage cyst on the left ovary. During the last 3 weeks she is experiencing dizziness and nausea. Occasionally she had fever and once vomiting without any apparent reasons. Her cycle was normal all this time. Today we got a call from physician that CA 125 came elevated (49). She is scheduled for the second gynecologist opinion visit next week.

Why ultrasound and MRI are somewhat controversial? Which one is more accurate in combination with CA 125 and symptoms? And what they suggest?

Obviosly she is very depressed. She is willing to take any surgery fearing of cause the worst. She is a strong person, but it breaks more and more often.

[vkk]

Just some additional info: age is 38, two kids (17 and 7), breast feeding, no family history