A pelvic MRI is often done to further evaluate cysts seen on other tests like ultrasound. Pelvic MRI can often characterize ovarian cysts and other lesions into risk categories for cancer.
Some radiologists use a system called O-Rads for MRI. This is a way to report lesions from a score of 1 to 5. 1 being benign representing normal ovary and 5 being highly concerning for cancer.
Does pelvic MRI show ovarian cysts?
Yes. It shows ovarian cysts and allows us to see if they have any features which allow a diagnosis of a benign lesion. MRI can also tell us if there are features which raise concern for cancer.
Why is a pelvic MRI done?
Pelvic MRI is more commonly done for problem solving or focused questions. Meaning, we do ultrasound of the pelvis for general symptoms and MRI to clear up any findings or unanswered questions.
What makes a cyst worrisome for cancer most?
When we see solid tissue in the cyst. This means the tissue inside the cyst enhances after giving contrast through an iv. This means the tissue does not represent simple water, blood or other fluid.
Another feature which is highly worrisome is spread of cancer to other parts of the abdomen or pelvis. We can see nodules or masses somewhere distant from the ovarian lesion. This can be seen as spread of cancer to other organs or nearby nodules and masses in the pelvis. Ascites or fluid is also a concerning feature which can mean spread of cancer.
Types of ovarian cysts on MRI
Benign functional cysts
These are benign and occur when an egg producing follicle in the ovary does not rupture and release the egg. Instead the follicle swells with fluid. These are considered benign normal findings when under 3 cm in a reproductive aged female not in menopause.
These are tumors which are often asymptomatic and have tissue or organ components. These can include: hair, nails, teeth, cartilage, fat and other tissues.
They are diagnosed when we see a complex lesion with fat inside. These have minimal risk of cancer. Those which contain solid tissue become more concerning for transformation to a cancer and are intermediate risk.
Hemorrhagic cysts are those follicles which swell up with fluid and bleed. We can diagnose these on MRI when we see hemorrhagic fluid inside the cyst but no solid components. These are low concern for cancer.
These are cystic lesions which are associated with endometriosis in the ovaries. We often see findings on MRI suggesting bleeding into the cysts. There are some specific signs that favor endometrioma over hemorrhagic cyst (shading sign) on MRI.
Complex cysts and cysts related to tumors
Cysts which do not fall into clearly benign categories as described above are complex and can have risk for cancer depending on their appearance on MRI.
Solid enhancing tissue makes the concern for tumor higher. Cancer found elsewhere in the body makes the concern for an ovarian lesion being cancer higher.
Most other cysts have minimal to low risk for cancer based on their appearance. This can be categorized based on o-rads criteria.
Pelvic MRI For Ovarian Cysts: Summary
Pelvic MRI for ovarian cysts is a helpful test to further evaluate a cyst found on other imaging studies, often ultrasound. We can assign risk of cancer to cysts using MRI. Often we are most concerned about solid tissue in the cysts and cancer spread somewhere else.