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O-RADS MRI Risk Stratification (Adnexal Lesion)

ACR O-RADS MRI (2022)

Assigns the ACR O-RADS MRI score (0–5) to a sonographically indeterminate adnexal lesion from its composition, fluid and lipid content, and the DCE time-intensity curve (or non-DCE early enhancement) of any solid tissue, with the associated malignancy PPV and management pathway.

Also searched as: ovary · dce · dwi · gynecology · ovarian · mass

Technically adequate MRI examination?
Peritoneal, mesenteric, or omental nodularity / irregular thickening (with or without ascites)

When present with an adnexal lesion, the study is scored O-RADS MRI 5.

Dominant finding

Solid tissue = enhancing papillary projection, mural nodule, irregular septation/wall, or larger solid portion. Clot, debris, fat, and thin smooth septa are not solid tissue.

Unilocular cyst — fluid content
Unilocular cyst — wall enhancement
Lipid-containing lesion — enhancing solid tissue
Dilated tube — fluid and wall
Solid tissue homogeneously dark on T2 AND dark on DWI?

Typical of fibrous benign lesions (e.g., fibroma); scores O-RADS MRI 2.

Enhancement assessment method
DCE time-intensity curve of solid tissue
Non-DCE — solid tissue enhancement vs myometrium at 30–40 s
Information
Incomplete input
  • The following information is still needed: technical adequacy of the MRI examination.

How this tool works

The O-RADS MRI system (ACR, 2022) adapts the ADNEX MR scoring approach. Lesions without enhancing solid tissue are almost certainly benign (score 2), with specific exceptions: unilocular cysts containing proteinaceous, hemorrhagic, or mucinous fluid and multilocular cysts are low risk (score 3). Solid tissue that is homogeneously dark on both T2 and DWI remains score 2. Other solid tissue is graded by its enhancement kinetics: a low-risk DCE curve is score 3, an intermediate-risk curve is score 4, and a high-risk curve is score 5. When DCE is not feasible, enhancement of solid tissue at 30–40 seconds relative to myometrium separates score 4 (≤ myometrium) from score 5 (> myometrium). A large volume of enhancing solid tissue within a lipid-containing lesion is score 4, and peritoneal, mesenteric, or omental disease places the study in score 5. Category PPVs are <0.5%, ~5%, ~50%, and ~90% for scores 2–5.

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