O-RADS Calculator

Ovarian-Adnexal Reporting and Data System - ACR risk stratification

1 Select Imaging Modality

Patient Status

2 Lesion Characteristics (US)

Lesion Type

Classic Benign Type

Lesion Size (cm)

Inner Wall/Septation

Solid Component

Solid Contour (for solid lesions)

3 High-Risk Features

Ascites Free fluid not explained by other causes

Peritoneal nodules Nodularity on peritoneal surfaces

2 Lesion Characteristics (MRI)

Lesion Type

Fluid Content

Wall Enhancement

Enhancing Solid Tissue

Papillary projection, mural nodule, irregular wall/septa, or larger solid portion

"Dark T2 / Dark DWI" Pattern

Homogeneous low signal on T2 AND high b-value DWI (fibroma, Brenner)

3 Enhancement Assessment

DCE MRI Available?

Time Intensity Curve (TIC)

Enhancement at 30-40 seconds

4 High-Risk Features

Peritoneal/mesenteric/omental nodularity With or without ascites → O-RADS MRI 5

Ascites with peritoneal thickening Suspicious for carcinomatosis → O-RADS MRI 5

About O-RADS

The Ovarian-Adnexal Reporting and Data System (O-RADS) is an ACR-developed risk stratification system that standardizes reporting and management of adnexal masses. It provides consistent terminology and evidence-based malignancy risk estimates.

O-RADS Scoring Overview

Score	US Risk	MRI Risk	Management
1	Normal	Normal/Physiologic	Routine care
2	<1%	<0.5%	Routine follow-up or none
3	1-10%	~5%	Short-term follow-up or MRI
4	10-50%	~50%	Surgical consultation
5	>50%	>90%	GYN oncology referral

O-RADS US v2022

Classic Benign Lesions (Score 2)

Simple cyst: Anechoic, smooth walls, no solid component (any size premenopausal; ≤10cm postmenopausal)
Hemorrhagic cyst: Retractile clot, lace-like/fishnet strands
Dermoid: Echogenic lines/dots, fat-fluid level, Rokitansky nodule
Endometrioma: Homogeneous ground-glass echoes, no solid
Hydrosalpinx: Tubular, incomplete septa, cogwheel sign

Key US Features

Solid component: Strongest predictor of malignancy
Irregular inner wall: Papillary projections >3mm
Size ≥10cm: Upgrades multilocular without solid from 3 to 4
Ascites/peritoneal nodules: Automatic score 5

O-RADS MRI 2021

Solid Tissue Definition

Enhancing tissue with specific morphology:

Papillary projection: Branching from wall/septum
Mural nodule: >3mm nodular component
Irregular wall/septation: Uneven margins
Larger solid portion: Other enhancing solid tissue

NOT solid tissue: Smooth thin walls/septa, Rokitansky nodule, endosalpingeal folds, clot, debris

"Dark T2 / Dark DWI" Pattern

Homogeneous low signal on BOTH T2WI and high b-value DWI (entire lesion). Typical of fibroma, fibrothecoma, Brenner tumor. These are O-RADS MRI 2 regardless of enhancement.

Time Intensity Curve (TIC)

TIC Type	Pattern	O-RADS Score
Low-risk	Gradual rise, no shoulder/plateau	3
Intermediate	Shoulder + plateau, less steep than myometrium	4
High-risk	Steep rise ≥ outer myometrium, then plateau/washout	5

References

Andreotti RF, Timmerman D, Strachowski LM, et al. O-RADS US Risk Stratification and Management System: A Consensus Guideline. Radiology. 2020;294(1):168-185. doi:10.1148/radiol.2019191150
Defined by ACR Committee. O-RADS US v2022: An Update. Radiology. 2023. doi:10.1148/radiol.230685
Thomassin-Naggara I, Defined by ACR, et al. O-RADS MRI Risk Stratification System. Radiology. 2020;294(2):328-339. doi:10.1148/radiol.2019201694
Defined by ACR Committee. O-RADS MRI Lexicon and Risk Stratification. Radiology. 2021. doi:10.1148/radiol.204371
Defined by ACR Committee. O-RADS MRI Risk Stratification: Pearls and Pitfalls. Insights Imaging. 2024;15:49. doi:10.1186/s13244-023-01577-5
American College of Radiology. O-RADS. ACR O-RADS

O-RADS Calculator

About O-RADS

O-RADS Scoring Overview

O-RADS US v2022

Classic Benign Lesions (Score 2)

Key US Features

O-RADS MRI 2021

Solid Tissue Definition

"Dark T2 / Dark DWI" Pattern

Time Intensity Curve (TIC)

References

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