IOTA ultrasound rules for ovarian masses
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The International Ovarian Tumor Analysis (IOTA) group ultrasound rules for ovarian masses are a simple set of ultrasound findings that classify ovarian masses into benign, malignant or inconclusive masses. These rules apply to masses that are not a classical ovarian mass (e.g. corpus luteum, endometrioma, dermoid cyst), which have pathognomonic imaging features.
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Masses can be classified as either benign or malignant using simple ultrasound features. Ovarian masses that cannot be classified (~25% of ovarian masses) into either group are classified as "inconclusive" (either having none or both benign and malignant features) and further evaluation by a specialist in ovarian imaging is recommended.
If an ovarian lesion has at least one of these features and no malignant features it can be confidently considered benign 1:
- unilocular cyst
- smooth multilocular tumor <10 cm
- solid components <7 mm in diameter
- presence of acoustic shadows
- no detectable Doppler signal
If an ovarian lesion has at least one of these features and no benign features it can be confidently considered malignant 1:
- irregular solid tumor
- irregular multilocular-solid mass >10 cm in diameter
- ≥4 papillary structures
- high Doppler signal (color score 4)
Treatment and prognosis
When the rules can be applied (~75% of masses), there is a sensitivity of ~90% and a specificity of ~95%, which is similar to subjective expert evaluation 1.
- 1. Timmerman D, Ameye L, Fischerova D et-al. Simple ultrasound rules to distinguish between benign and malignant adnexal masses before surgery: prospective validation by IOTA group. BMJ. 2010;341 (dec14 1): c6839. doi:10.1136/bmj.c6839 - Free text at pubmed - Pubmed citation
- 2. Kaijser J, Bourne T, Valentin L et-al. Improving strategies for diagnosing ovarian cancer: a summary of the International Ovarian Tumor Analysis (IOTA) studies. Ultrasound Obstet Gynecol. 2013;41 (1): 9-20. doi:10.1002/uog.12323 - Pubmed citation
- 3. Twickler DM, Moschos E. Ultrasound and assessment of ovarian cancer risk. AJR Am J Roentgenol. 2010;194 (2): 322-9. doi:10.2214/AJR.09.3562 - Pubmed citation