Why does O-RADS US have a low specificity in the higher risk categories with broad ranges of risk differing from the higher specificity of other RADS?
Unlike the SRU Consensus Statement, why does the O-RADS management scheme differentiate between classic benign lesions and simple cysts of the ovary that are less than 10 cm and those greater than or equal to 10 cm?
A cyst with a smooth inner margin and a thin septation is managed like a simple cyst according to the SRU Consensus. Why is this type of cyst considered a multilocular cystic lesion by O-RADS and managed in the O-RADS 3 rather than O-RADS 2 category?
Why does O-RADS not incorporate the early postmenopausal period in its system as the SRU Consensus does?
How does a unilocular cyst with a wall calcification fit into the risk stratification system?



FAQ-176: Why does O-RADS US have a low specificity in the higher risk categories with broad ranges of risk differing from the higher specificity of other RADS?

  

A papillary projection (or nodule) is a type of solid component that protrudes from the wall or septation of a cyst and is surrounded on 3 sides by fluid. In Category 4, in order to simplify the table, we grouped the unilocular cyst with a solid component that is not a papillary projection (0 papillary projections) with the unilocular cyst that contains up to 3 papillary projections in a single sub-category. To clarify this, we have modified this subcategory in an updated risk stratification table available on the ACR website. 


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Questions #177 – #180 

It has come to our attention that there are questions regarding the rationale behind O-RADS risk stratification and management recommendations that differ from the Society of Radiologists in Ultrasound (SRU) Consensus Statement guidelines of 2010. The SRU guidelines have been helpful in determining which cystic lesions require follow-up, further imaging, or a surgical procedure. However, unlike the SRU Consensus Statement, O-RADS is based on a standardized lexicon in order to categorize malignancy risk with subsequent standardization of interpretations. In addition, O-RADS standardized descriptors, based upon the IOTA model, have been tested on a large data set from phases 1–3 of the IOTA study to assign a risk of malignancy to each of them and provide recommended management strategies for each risk category. Percentile risk is not given in the SRU guidelines, nor are management strategies for higher risk lesions. The following address more specific questions, some that can be answered based upon evidence in the IOTA 1-3 data set.



FAQ-177: Unlike the SRU Consensus Statement, why does the O-RADS management scheme differentiate between classic benign lesions and simple cysts of the ovary that are less than 10 cm and those greater than or equal to 10 cm? 

  

The IOTA 1-3 data set places benign classic ovarian lesions and all unilocular cysts (simple or non-simple) with smooth inner margins, in a <1% risk category only when the size is < 10 cm. There is other evidence supporting a higher risk of malignancy in these larger classic benign lesions, some are referenced in the SRU Consensus Statement article. As O-RADS is based upon data using surgical specimens and simple (anechoic, unilocular) cysts were not separated from other non-simple unilocular smooth cysts, we are likely overestimating risk in the ≥ 10 cm simple cyst. However, one should also keep in mind that sonographic characterization of simple cysts of this larger size may be more difficult resulting in missed mural irregularities or nodules. We also plan to validate the O-RADS US risk stratification and management system using data from the IOTA 5 study, the largest multicenter prospective cohort study not only including patients selected for surgical procedures but also for conservative management. 


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FAQ-178: A cyst with a smooth inner margin and a thin septation is managed like a simple cyst according to the SRU Consensus. Why is this type of cyst considered a multilocular cystic lesion by O-RADS and managed in the O-RADS 3 rather than O-RADS 2 category?

  

While the risk of malignancy is extremely low for a cyst with a smooth inner margin and a single thin septation, the IOTA data which we used to determine our risk stratification did not differentiate between 1 or more septations. That said, the management for a single septation (if indeed smooth) would be for assessment by an US specialist or by MRI and would likely support the same conclusion of a benign lesion. What is more important than the number of septations is whether they are smooth or irregular and the amount of overall lesion flow by Doppler which does alter level of risk and was not specifically addressed by SRU.

   

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FAQ-179: Why does O-RADS not incorporate the early postmenopausal period in its system as the SRU Consensus does?


The gynecologists on the committee felt strongly that the definition of menopause should be consistent throughout the management recommendations. In the SRU guidelines, the differentiation of early from late post menopause is only made for the specific evaluation of a hemorrhagic cyst so that short interval follow up can be recommended. In the O-RADS system, this would be further managed by referral to an ultrasound specialist, gynecologist or for an MRI study. The specific selection of management choices would likely be influenced by the number of years post-menopause.    


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FAQ-180: Is there a difference in recommended management of a hydrosalpinx and peritoneal inclusion cyst in the SRU and O-RADS US systems?

There is no significant difference in the management recommendation of the SRU guidelines that recommend management “as clinically indicated” and O-RADS recommendation of “management by a gynecologist”. In order to clinically evaluate the patient for necessary treatment of problems unrelated to malignancy (i.e. fertility, endometriosis, infection, etc.) in these almost certainly benign lesions, management by a gynecologist is recommended.


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