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.
- 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.
- 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
- Allows for high-resolution evaluation of the ovaries and pelvic structures.
- Does not use ionizing radiation.
- Time consuming
- Requires significant patient cooperation to minimize motion artifact
CT with contrast
- Quick imaging exam which requires less patient cooperation than MRI.
- Utilizes ionizing radiation, which should be minimized for patients in reproductive age and children.
Iodine-123 nuclear scan
- 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.
- 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.
- 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.
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- Preliminary Diagnosis: Struma ovarii
- I. What imaging technique is first-line for this diagnosis?
- II. Describe the advantages and disadvantages of this technique for diagnosis of struma ovarii.
- III. What are the contraindications for the first-line imaging technique?
- IV. What alternative imaging techniques are available?
- V. Describe the advantages and disadvantages of the alternative techniques for diagnosis of struma ovarii.
- VI. What are the contraindications for the alternative imaging techniques?