November 3, 2023
By Angie N Choi, EdD, Author of Whole New Me: Healing From Cancer in Body, Mind, and Spirit
If you’ve recently been diagnosed with a ovarian cyst or tumor, you’re probably wondering what type of imaging tests you need to determine if it is benign (non-cancerous) or malignant (cancerous). Ultrasounds, CT Scans, and MRIs are the most common tests to determine whether a cyst or a tumor is likely to be cancerous prior to surgery. A cyst is a fluid-filled sac, and the majority of these are not cancerous and will resolve on their own.1 Tumors are more solid than cysts. They are abnormal masses of tissue that could be benign, premalignant, or malignant. If you’ve been told you have a mass on your ovaries, you shouldn’t immediately assume that you have cancer, but you should follow your doctor or gynecologist’s recommendations for continued monitoring or further testing as needed. If your doctor suspects the mass is cancerous, then you will be referred to a gynecologic oncologist, and CT scans or MRIs may be ordered to get a clearer picture of the pelvis and abdomen to make plans for treatment. In this article we’ll explain what each scan is, why it is ordered, when it is typically ordered, and what each experience is like for the patient.
Comparing Ultrasounds, CT Scans, and MRIs for Ovarian Cancer
The table below provides a comparison between different types of imagining tests that doctors may order to discriminate between benign and malignant masses prior to surgery.2,3 It is actually during surgery that a biopsy of the tissue is taken and examined to formally diagnose ovarian cancer. This means that you won’t actually know for certain if you have ovarian cancer until after surgery, though your oncologist may strongly suspect it based on your symptoms, cancer antigen blood tests (CA-125), and scans. Surgery is a highly invasive procedure, so doctors order imaging tests beforehand to characterize tumors (origin, size, shape, extent). Their goal is to have the clearest picture of the internal cavity, tissues, and organs to ensure that surgery (as needed) will be as accurate and successful as possible.
Ovarian Cancer Imaging Tests
| Imaging Test | Why is it ordered? | When is it ordered? | What does it feel like? |
|---|---|---|---|
| Ultrasound (Transvaginal or Transabdominal) Uses high-frequency sound waves and translates those frequencies to create images of ovaries. | To visualize the ovaries and detect abnormalities like cysts and tumors inside the ovaries To take serial images or monitor changes in ovaries over time To assess the presence of fluid in the abdominal cavity | The first imaging test typically ordered after patients communicate symptoms such as pelvic pain, bloating, or menstrual cycle changes or abnormalities, urinary frequency, weight changes Ultrasounds are the first choice for imaging for its availability, high resolution, and lack of radiation exposure. | Maybe uncomfortable but not painful Patient lies down on examination table. Sonographer will gently insert a lubricated transducer into the vagina and gently maneuver it to take images of the ovaries. Takes 15-30 minutes. If a transabdominal scan is performed, it is much less invasive and uncomfortable. Transducer will come into contact with the surface of the skin of abdomen to take images. |
| Imaging Test | Why is it ordered? | When is it ordered? | What does it feel like? |
| CT Scan (Computed Tomography) Uses x-rays to take multiple images of the body from different angles. The computer then takes these images to create cross-sectional slices or 3D image compilations. | To provide images of pelvic and abdominal regions to define location and size of tumors, masses, or ascites (fluid build-up) To determine stage of cancer and spread to other organs To assess lymph nodes (if cancer spread to lymph nodes) To plan cancer treatment (surgery, chemotherapy) To detect recurrence of cancer after therapy | If results of transvaginal ultrasound suggest ovarian masses or ovarian cancer is suspected, CT scan is ordered. | Exposes patient to radiation. In some cases, patients will have a contrasting agent (dye) injected into a vein or drink a contrasting liquid. May experience a warm sensation spreading through the body or metallic taste in mouth. Warm sensation may make patients feel like they need to urinate. Patient lies down on an exam table that moves into a CT scanner (large ring-shaped machine that is open not enclosed. Patient must remain still. Will hear whirring or clicking sounds but it is not uncomfortable. Radiologic technologist will provide instructions and keep contact through intercom. Midway through the process, more contrast may be injected. Takes about 30 minutes. |
| Imaging Test | Why is it ordered? | When is it ordered? | What does it feel like? |
| MRI (Magnetic Resonance Imaging) Imaging technique that uses strong magnetic field and radio waves to create detailed cross-sectional images of body. | To provide detailed images of soft tissues To determine the site of origin of masses To help characterize ovarian masses and their nature (size, shape, composition) for treatment decisions To determine stage of cancer To plan and guide surgical procedures To prevent unnecessary surgeries on benign masses due to unclear images of lesions on ultrasounds To evaluate complications (ovarian cancer may lead to complications in bowels or other nearby organs) To assess post-treatment response (see if tumor is shrinking after treatment) MRIs are highly sensitive in identifying malignant lesions (abnormal-looking tissues), so especially beneficial for women who have low risk for malignancy but have unclear lesions on ultrasounds. | If results of ultrasound or CT scans are uncertain, an MRI may be ordered. | Painless procedure Discomfort is only from loud noises heard during scanning process. Patient lies down on table that slides into the MRI scanning machine, a long tunnel-like structure. It may be anxiety-inducing for claustrophobic people. For those who are claustrophobic, a Prenuvo MRI scan is an unconfined alternative. Patient will be given ear plugs or headphones, but still hear loud, knocking, clanging, or thumping noises. Patient must remain still. MRI technologist and patient maintain contact through intercom. Takes about 45 minutes. No radiation exposure so good for younger female patients; uses magnetic field instead. |
In my case, I did not have an ultrasound because the tumor was found during an MRI for back pain. I had two MRIs and a CT scan which all corroborated that the tumor was highly suspicious for malignancy. I wrote another article here about my ovarian cancer diagnosis through an MRI and how I healed from it using a metabolic approach to cancer with the therapeutic ketogenic diet at the main pillar of treatment.
What Ovarian Cancer Looks Like on Ultrasounds, CT Scans, and MRIs
Ovarian cancer may appear on transvaginal ultrasounds as papillary excrescences (bumpy, uneven growths on the surface of tumors), irregular walls (walls that don’t look normal), or thick septations (thick walls divided into compartments by walls inside them).4 On color Doppler ultrasound images, tumors often show blood vessels with low resistance because they don’t have the usual muscular walls, and there are abnormal connections between arteries and veins (arteriovenous shunts).5 These vessels also tend to bunch together in groups. This can help doctors identify tumors when they see these unusual blood vessel patterns. Although transvaginal ultrasounds are the first scans typically done when patients complain of symptoms, they are not sensitive enough to screen for ovarian cancer. There is a high incidence of benign cysts that are difficult to distinguish from tumors on these scans, and due to the small size of ovaries and their positions inside the pelvic region, one ovary may not even be seen on sonograms due to bowel shadowing, fibroids, or other factors.6 Then, other imaging tests are typically ordered.
Ovarian cancer may appear on CT scans as cysts with thick walls and divisions within the walls known as septations. CT scans may also indicate the presence of fluid build-up (ascites) which may be a sign of a late-stage ovarian cancer.7 Additionally, CT scans may help identify any enlarged lymph nodes in the surrounding areas, providing critical information for staging the cancer and guiding treatment decisions. However, when it comes to lymph nodes, CT scans do not provide clear diagnostic performance for ovarian cancer. CT scans are not usually used to distinguish between different types of ovarian masses because they are not great at showing detailed differences in soft tissues. They are mainly used for looking at fatty tissue and calcifications.8
Ovarian cancer presents on MRI scans somewhat similarly to CT scans with cystic lesions, septations, and solid components. A septal (division) wall thickness greater than 3 mm, nodules (small, bumpy, or irregular areas) that are greater than 4 cm, and necrosis (cellular death) may be signs of ovarian cancer.7 Depending on the type of image produced or contrast agent used in the MRI, necrosis may appear darker (T1-weighted images), brighter (T2-weighted images), or non-enhanced/not lit up (gadolinium-enhanced images) compared to healthy tissues.7 MRIs outperform CT images in detecting ovarian cancer, but identifying cancerous lymph nodes is also problematic in MRIs.
Medical imaging scans are typically prescribed to assess the nature of cysts or abnormal tissues, and to discern whether they are benign, premalignant, or malignant. In the event of discovering cysts, it is important for patients not to become unduly alarmed as most cysts are benign. Physicians use these images to differentiate cysts accurately and when surgery is necessary, they exercise caution in formulating surgical plans. Surgical interventions should only be pursued when deemed essential and should avoid unnecessary risks for the patient. Consequently, patients should regard these scans as valuable sources of information for making well-informed decisions regarding their treatment.
References
1InformedHealth.org [Internet]. Cologne, Germany: Institute for Quality and Efficiency in Health Care (IQWiG); 2006-. Ovarian cysts: Overview. 2019 Mar 28. Available from: https://www.ncbi.nlm.nih.gov/books/NBK539572/
2 Foti PV, Attinà G, Spadola S, Caltabiano R, Farina R, Palmucci S, Zarbo G, Zarbo R, D’Arrigo M, Milone P, Ettorre GC. MR imaging of ovarian masses: classification and differential diagnosis. Insights Imaging. 2016 Feb;7(1):21-41
3Iyer VR, Lee SI. MRI, CT, and PET/CT for ovarian cancer detection and adnexal lesion characterization. AJR. 2010 Feb; 194(2):311-321.
4 Fleischer AC, Lyshchik A, Hirari M, Moore RD, Abramson RG, Fishman DA. Early detection of ovarian cancer with conventional and contrast-enhanced transvaginal sonography: recent advances and potential improvements. J Oncol. 2012 Jan 1;2012.
5Fleischer AC, Cullinan JA, Peery CV, Jones III HW. Early detection of ovarian carcinoma with transvaginal color Doppler ultrasonography. AJOG. 1996 Jan 1;174(1):101-6.
6Campbell S, Gentry-Maharaj A. The role of transvaginal ultrasound in screening for ovarian cancer. Climacteric. 2018 May 4;21(3):221-6.
7Engbersen MP, Van Driel W, Lambregts D, Lahaye M. The role of CT, PET-CT, and MRI in ovarian cancer. Br J Radiol. 2021 Sep 1;94(1125):20210117.
8Togashi, K. Ovarian cancer: the clinical role of US, CT, and MRI. Eur Radiol 13 (Suppl 6), L87–L104 (2003)