Preliminary Diagnosis: Struma ovarii
I. What imaging technique is first-line for this diagnosis?
- Ultrasound (US) of the pelvis with transabdominal and endovaginal imaging for evaluation of the ovaries.
II. Describe the advantages and disadvantages of this technique for diagnosis of struma ovarii.
Advantages
- Allows for evaluation of the ovaries, adnexa, and uterus.
- Relatively quick examination which does not utilize ionizing radiation.
- Useful in determining characteristics of ovarian lesions.
- Can allow for assessment of vascular flow to ovarian lesions.
- Cost-effective imaging modality.
- If normal-appearing ovaries are seen, a diagnosis of struma ovarii can be excluded.
Disadvantages
- Very operator-dependent, and relies heavily on the skill of the technologist or physician performing the exam.
- Can be significantly degraded by patient body habitus and bowel gas content.
- Endovaginal ultrasound, while more sensitive, is uncomfortable to some patients.
III. What are the contraindications for the first-line imaging technique?
- There are no significant contraindications to transabdominal US examination of the pelvis.
- Endovaginal US is much more sensitive, but may be declined by a subset of patients.
IV. What alternative imaging techniques are available?
- Magnetic resonance imaging with intravenous gadolinium contrast.
- Computed tomography (CT) with intravenous contrast.
- Iodine-123 nuclear scan.
V. Describe the advantages and disadvantages of the alternative techniques for diagnosis of struma ovarii.
Magnetic resonance imaging (MRI) with contrast
Advantages
- Allows for high-resolution evaluation of the ovaries and pelvic structures.
- Does not use ionizing radiation.
Disadvantages
- Expensive
- Time consuming
- Requires significant patient cooperation to minimize motion artifact
CT with contrast
Advantages
- Quick imaging exam which requires less patient cooperation than MRI.
- Cost-effective.
Disadvantages
- Utilizes ionizing radiation, which should be minimized for patients in reproductive age and children.
Iodine-123 nuclear scan
Advantages
- Iodine-123 will be taken up by any functioning thyroid tissue, and is diagnostic of struma ovarii if seen in the adnexal region.
- Can be done with Spect-CT imaging, allowing for CT and nuclear evaluation in the same examination.
Disadvantages
- Lengthy examination.
- Significant radiation dose that requires extensive patient preparation, post-imaging instructions, and occasionally patient isolation.
VI. What are the contraindications for the alternative imaging techniques?
MRI with contrast
- Patients with embedded metallic devices not made of titanium such as cardiac pacers, stents, and other non-MR approved metallic devices may not enter the magnet for imaging.
- Patients with GFR <30 cannot receive gadolinium intravenous contrast.
CT with contrast
- Contraindicated in pregnancy, especially 1st and 2nd trimester.
- Intravenous contrast should not be administered in patients with renal insufficiency, creatinine>1.6 mg/dL
- Allergy to iodinated contrast media requires premedication per department protocol or in severe cases should not be given.
Iodine-123
- Contraindicated in pregnant patients or patients who plan on becoming pregnant within 6 months.
- Patients on thyroid replacement therapy will need to discontinue medication for 3-4 days prior to examination.
Copyright © 2017, 2013 Decision Support in Medicine, LLC. All rights reserved.
No sponsor or advertiser has participated in, approved or paid for the content provided by Decision Support in Medicine LLC. The Licensed Content is the property of and copyrighted by DSM.
