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O-RADS MRI Calculator – ACR Guidelines


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Refer ACR ORADS MRI Chart Below

You can hover over/click a few tabs for illustrations for eg. Time intensity curves.

More useful tools:

Images for reference have been sourced from the original white paper of the ACR. You can access the full article here: O-RADS MRI Risk Stratification System: Guide for Assessing Adnexal Lesions from the ACR O-RADS Committee. The calculator is based on a fairly complex flowchart by Dr. Mohamadian A et.al in their KJR article.

ORADS MRI Chart

Ovarian-Adnexal Reporting and Data System (O-RADS) MRI risk stratification system
Ovarian-Adnexal Reporting and Data System (O-RADS) MRI risk stratification system. DCE = dynamic contrast enhanced, DWI = diffusion-weighted imaging, N/A = not applicable, PPV = positive predictive value.

ORADS MRI Risk Stratification

Key Takeaway Box

O-RADS MRI Risk Stratification SystemKey Takeaways
What is it?A standardized system for assessing and reporting adnexal lesions on MRI, with a corresponding risk stratification for malignancy.
Why is it important?To help radiologists and referring physicians make informed decisions about the management of patients with adnexal lesions.
How does it work?The system assigns a risk score of 1-5 to each lesion, based on its MRI features. Lesions with a score of 1 or 2 are considered to be at low risk for malignancy, while lesions with a score of 4 or 5 are considered to be at high risk for malignancy.
What are the benefits?The O-RADS MRI risk stratification system can help to reduce unnecessary surgery in patients with benign lesions, and ensure that patients with malignant lesions are referred for appropriate management.

Introduction

Adnexal lesions are masses or cystic lesions that arise from the ovary, fallopian tube, or parametrium. MRI is an important imaging modality for the evaluation of adnexal lesions, as it can provide detailed information about their morphology, signal intensity, and enhancement characteristics.

The O-RADS MRI risk stratification system is a standardized system for assessing and reporting adnexal lesions on MRI. The system assigns a risk score of 1-5 to each lesion, based on its MRI features. Lesions with a score of 1 or 2 are considered to be at low risk for malignancy, while lesions with a score of 4 or 5 are considered to be at high risk for malignancy.

O-RADS MRI Lexicon

The O-RADS MRI lexicon provides standardized terms and definitions for assessing and reporting adnexal lesions on MRI. This helps to ensure that radiologists are using the same terminology when describing adnexal lesions, which can improve communication and consistency.

Some of the key terms in the O-RADS MRI lexicon include:

  • Adnexal lesion: Any mass or cystic lesion arising from the ovary, fallopian tube, or parametrium.
  • Solid tissue: Tissue with a high signal intensity on T2-weighted MRI.
  • Nonsolid tissue: Tissue with a low signal intensity on T2-weighted MRI.
  • Wall enhancement: Enhancement of the wall of an adnexal lesion on contrast-enhanced MRI.
  • Septations: Thin walls that divide an adnexal lesion into multiple compartments.
  • Nodules: Small, solid lesions within an adnexal lesion.

O-RADS MRI Risk Stratification System

The O-RADS MRI risk stratification system assigns a risk score of 1-5 to each adnexal lesion, based on its MRI features. The risk score is determined by considering the following factors:

  • Cystic versus solid: Solid lesions are generally considered to be at higher risk for malignancy than cystic lesions.
  • Unilocular versus multilocular: Multilocular cystic lesions are generally considered to be at higher risk for malignancy than unilocular cystic lesions.
  • Margin regularity: Lesions with irregular margins are generally considered to be at higher risk for malignancy than lesions with regular margins.
  • Enhancement characteristics: Lesions that enhance strongly on contrast-enhanced MRI are generally considered to be at higher risk for malignancy than lesions that do not enhance strongly.

Interpretation of the O-RADS MRI Risk Stratification Score

The O-RADS MRI risk score has six categories:

O-RADS MRI ScorePPV for MalignancyDescription
0Incomplete examinationCannot adequately assess the lesion due to technical limitations or incomplete imaging.
1Almost certainly benign(<0.5%)Normal ovaries, including follicles and corpus luteal cysts.
2Almost certainly benign(<0.5%)Benign lesions with classic MRI features, such as simple cysts, hemorrhagic cysts, dermoids, and endometriomas.
3Low risk(approximately 5%)Lesions with indeterminate or low-risk features, such as complex cysts with a few thin septations, small papillary excrescences, or minimal solid components that enhance with a low-risk curve.
4Intermediate risk(approximately 50%)Lesions with high-risk features, such as large solid components, enhancing solid tissue with an intermediate-risk curve, or papillary projections or mural nodules.
5High risk(approximately 90%)Lesions with features highly suggestive of malignancy, such as large solid components, enhancing solid tissue with a high-risk curve, or extracapsular extension.
MRI O-RADS Categories

Benefits of the O-RADS MRI Risk Stratification System

The O-RADS MRI risk stratification system offers a number of benefits, including:

  • Reduced unnecessary surgery: The system can help to reduce unnecessary surgery in patients with benign adnexal lesions. This is because the system allows radiologists to more accurately assess the risk of malignancy for each lesion.
  • Improved patient outcomes: The system can help to improve patient outcomes by ensuring that patients with malignant adnexal lesions are referred for appropriate management in a timely manner.
  • Improved communication: The system provides a standardized framework for assessing and reporting adnexal lesions on MRI. This can improve communication between radiologists and referring physicians, which can lead to better patient care.
  • Reduced costs: The system can help to reduce healthcare costs by reducing unnecessary surgery and ensuring that patients with malignant adnexal lesions are managed appropriately.

Limitations of the O-RADS MRI Risk Stratification System

The O-RADS MRI risk stratification system is not without its limitations. One limitation is that it is not validated in all patient populations. For example, the system has not been extensively studied in pregnant women or women with a history of pelvic surgery.

Another limitation of the system is that it requires radiologists to be familiar with the system and its terminology. This can be a challenge for radiologists who are not trained in gynecologic imaging.

Future Directions of the O-RADS MRI Risk Stratification System

The O-RADS MRI risk stratification system is still under development. Some of the areas that are being explored for future development include:

  • Validation of the system in all patient populations
  • Development of management recommendations based on the O-RADS MRI risk score
  • Development of artificial intelligence (AI) tools to help radiologists implement the system

Conclusion

The O-RADS MRI risk stratification system is a valuable tool for radiologists and referring physicians in managing patients with adnexal lesions. The system can help to reduce unnecessary surgery, improve patient outcomes, and improve communication between radiologists and referring physicians.

While the system does have some limitations, it is a powerful tool that can help to improve the care of patients with adnexal lesions. The system is still under development, and there are a number of areas where future research is needed. However, the system is already being used by radiologists around the world to improve the care of their patients.

Check out this case-based ORADS MRI discussion [MEMBERS ONLY]

For some reason the preferred search term for O-RADS is o’rads. Probably an indexing error.

Disclaimer: The author makes no claims of the accuracy of the information contained herein; this information is for educational purposes only and is not a substitute for clinical judgment.

References:

  1. O-RADS MRI Risk Stratification System: Guide for Assessing Adnexal Lesions from the ACR O-RADS Committee Elizabeth A. Sadowski, Isabelle Thomassin-Naggara, Andrea Rockall, Katherine E. Maturen, Rosemarie Forstner, Priyanka Jha, Stephanie Nougaret, Evan S. Siegelman, and Caroline ReinholdRadiology 2022 303:1, 35-47
  2.  Mohamadian A, Moradi B. Simplified Approach for Ovarian-Adnexal Reporting and Data System MRI Risk Stratification System. Korean J Radiol. 2022 Nov;23(11):1115-1117. https://doi.org/10.3348/kjr.2022.0489CopyDownload Download with Abstract 

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