What is the difference between a papillary projection and a solid component? How are they differentiated in the risk stratification table?  
The terms “solid smooth” and “solid irregular” appear as sub-categories in risk categories 3, 4 and 5. Does this refer to a lesion or any solid component within a lesion?
Differentiating among types of characteristic cyst fluid (endometrioma, mucinous tumor, dermoid) can be challenging. Are there some tips that may be helpful to the user?
Although the benign predictive value of the descriptor, “acoustic shadowing” for solid lesions is mentioned in the original JACR lexicon publication, why was this descriptor not included in risk stratification??
Since the color score is a subjective evaluation, are there tips that will help to distinguish between minimal (color score 2) and moderate flow (color score 3), as well as moderate (color score 3) and strong flow (color score 4)? Does spectral Doppler play any role?
Would a cyst that contains a “daughter cyst” be considered multilocular?
How does a unilocular cyst with a wall calcification fit into the risk stratification system?



FAQ-168: What is the difference between a papillary projection and a solid component? How are they differentiated in the risk stratification table?

  

 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. 


Original table: 


New version table:  


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FAQ-169: The terms “solid smooth” and “solid irregular” appear as sub-categories in risk categories 3, 4 and 5. Does this refer to a lesion or any solid component within a lesion? 

  

As each of the prior subcategories within each risk category refer to a unilocular or multilocular cyst, “solid smooth” and “solid irregular” refers to a solid lesion (≥ 80% solid or solid appearing) being the 5th major subcategory used in the IOTA/O-RADS system. Understanding this confusion, we have modified these terms to “solid lesion” in each of the risk groups in an updated table available on the ACR O-RADS web page


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FAQ-170: Differentiating among types of characteristic cyst fluid (endometrioma, mucinous tumor, dermoid) can be challenging. Are there some tips that may be helpful to the user?

  

Typically, “homogeneous low level” or “ground glass” echoes are evenly dispersed tiny echoes within a cyst which represent blood products in an endometrioma (1) as opposed to “scattered” echoes of variable size and echogenicity that are heterogeneously dispersed echogenic foci within cystic contents that is more representative of mucinous material.(2) Mucinous fluid is also more likely to be mobile and show streaming when pressure is applied by the transducer or with color Doppler than the blood products with an endometrioma due to relative decrease in viscosity. Another type of cyst content to be differentiated are the “hyperechoic line and dots” representing hair within the liquified component of a dermoid cyst. The key to this diagnosis is the more linear appearance of these foci. (3) While the difference between these echoes can be challenging, the assessment category is the same (O-RADS 2) for endometrioma, dermoid cyst and (indeterminate) non-simple unilocular cyst and management is not significantly affected. Please refer to figures below. 


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FAQ-171: Although the benign predictive value of the descriptor, “acoustic shadowing” for solid lesions is mentioned in the original JACR lexicon publication, why was this descriptor not included in risk stratification?


Keeping the table simple, with less categories was felt to be extremely important in this first publication of O-RADS. After a careful review of the literature and IOTA 1-3 data, we also concluded that using the descriptor approach, management did not vastly change for the majority of these lesions irrespective of “acoustic shadowing”. We did recognize that the omission of separate categories of solid or solid component with acoustic shadowing will result in a higher ORADS score in some patients but felt the benefits of table simplicity as well as sacrificing specificity over sensitivity and erring on the side of caution was prudent at that time. However, this will be included in the next revision. This sonographic risk reduction may also be obtained using the ADNEX mathematical model1, an alternative approach that is part of the O-RADS System.    


Reference:

Van Calster B, Van Hoorde K, Valentin L, et al. Evaluating the risk of ovarian cancer before surgery using the ADNEX model to differentiate between benign, borderline, early and advanced stage invasive, and secondary metastatic tumours: prospective multicentre diagnostic study. BMJ 2014; 349: g5920.



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FAQ-172: Since the color score is a subjective evaluation, are there tips that will help to distinguish between minimal (color score 2) and moderate flow (color score 3), as well as moderate (color score 3) and strong flow (color score 4)? Does spectral Doppler play any role?


The color score is an overall subjective assessment of color Doppler flow within the entire lesion, excluding any adjacent normal ovarian parenchyma. When color Doppler flow demonstrates only minimal flow after adjusting settings for maximum sensitivity of low blood flow states, this would be considered minimal flow, color score 2. Some vendors offer automated “low flow” settings, while others require selective adjustments of parameters including color Doppler gain, scale (4cm/sec), pulse repetition frequency and wall filters. Additional operator selections to maximize flow detection include the use of power Doppler and decreasing the size of the Doppler box to the region of interest. In contrast, when color Doppler flow is robust and easily obtained throughout the solid components of the lesion, this would be considered color score 4. Anything in between would be considered moderate flow, color score 3. Spectral Doppler is useful as an adjunct to distinguish vascularity from artifact when vessels are not clearly delineated with color Doppler, however, plays no other role in determining the color score.  


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FAQ-173: Would a cyst that contains a “daughter cyst” be considered multilocular?


A daughter cyst is defined as partial volume averaging of an adjacent, small support follicle that appears to project within a larger unilocular cyst or follicle on a given image however, as one scans through the lesion either in real-time time or via a cine-clip, the two can be separated. This is only applicable to premenopausal patients. A “cyst within a cyst” that can be separated from the inner wall or ovarian parenchyma is a septation and the entire cyst would be considered multilocular.  


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FAQ-174: How does a unilocular cyst with a wall calcification fit into the risk stratification system?


If there is a protrusion from the wall of the cyst inside the cyst cavity that is < 3 mm in height, whether it is calcified or not, it will be an irregularity of the wall. If the protrusion is ≥ 3 mm, it is a papillary projection or nodule. A flat wall calcification that does not protrude within the cavity would be considered a smooth inner wall. Other descriptors such as “shadowing” (ADNEX model) would also be helpful for better prediction of malignancy.  


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FAQ-175: 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?

  

For the purposes of risk stratification, ascites is defined as fluid extending beyond the cul-de-sac superior to the uterine fundus if the uterus is anteverted or anteflexed, or fluid anterior and superior to the uterus, if the uterus retroverted or retroflexed. Echoes within the fluid do not play any role in risk stratification but may change the management strategy if the patient presents with acute symptoms.  


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