O-RADS MRI · Adnexal Mass Assessment

Step-by-step decision

Choose step by step as prompted; reaching an endpoint gives the management recommendation. You can go back a step or restart anytime.

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Full pathway

1. [Decision] Lesion composition
   Lesion composition (for ultrasound-indeterminate adnexal lesions)? (MRI for ultrasound-indeterminate adnexal lesions (accuracy ~91%, cutoff ≥4 for malignancy). Core: enhancing solid tissue = potentially malignant, complete absence of enhancement = reliably benign; solid T2-dark + DWI-dark = fibrous (e.g. fibroma, benign). With DCE, classify by time-intensity curve (TIC).)
   • Normal ovary / non-adnexal source → O-RADS MRI 1 · normal
   • Pure cyst / endometrioma / fat (no enhancing solid); or solid T2-dark + DWI-dark → O-RADS MRI 2 · almost certainly benign
   • Contains enhancing solid tissue → Enhancing solid · TIC classification
2. [End] O-RADS MRI 1 · normal
   O-RADS MRI 1 (normal ovary/non-adnexal source): MRI can reclassify a lesion as non-adnexal (sensitivity ~99%); no adnexal malignancy management needed.
3. [End] O-RADS MRI 2 · almost certainly benign
   O-RADS MRI 2 (almost certainly benign, PPV <1%): pure cyst/endometrioma/fat with no enhancing solid, or a T2-dark + DWI-dark fibrous lesion; manage/follow up as benign.
4. [Decision] Enhancing solid · TIC classification
   TIC type of the enhancing solid tissue / enhancement relative to outer myometrium? (TIC type 1 slow rise no shoulder, type 2 moderate (enhancement ≤ myometrium, plateau), type 3 rapid rise (> myometrium, washout). Without DCE, use enhancement relative to outer myometrium: ≤ outer myometrium → 4, > outer myometrium → 5 (type 3 cannot be assigned without DCE). Peritoneal/omental implants → 5.)
   • TIC type 1 (slow rise) → O-RADS MRI 3 · low risk (~PPV 5%)
   • TIC type 2 / enhancement ≤ outer myometrium → O-RADS MRI 4 · intermediate risk (~PPV 50%)
   • TIC type 3 / enhancement > outer myometrium, or peritoneal/omental implants → O-RADS MRI 5 · high risk (~PPV 90%)
5. [End] O-RADS MRI 3 · low risk (~PPV 5%)
   O-RADS MRI 3 (low risk, PPV ~5%): contains enhancing solid but TIC type 1 slow rise; gynecology assessment, often conservative/follow-up or elective surgery, integrating clinical context.
6. [End] O-RADS MRI 4 · intermediate risk (~PPV 50%)
   O-RADS MRI 4 (intermediate risk, PPV ~50%; TIC type 2/enhancement ≤ myometrium, the weak zone of this system): gynecologic oncology consult; integrate DWI/morphology/CA125 for further stratification and surgical decision.
7. [End] O-RADS MRI 5 · high risk (~PPV 90%)
   O-RADS MRI 5 (high risk, PPV ~90%; TIC type 3 rapid rise/enhancement > myometrium, or peritoneal implants): gynecologic oncology consult/surgery + complete staging.

Source guidelines & references

• ACR O-RADS MRI risk stratification (Radiology 2021) · source ↗
• O-RADS MRI multicenter prospective validation (EURAD)

This pathway is our own synthesis of the decision logic in the guidelines above (not the guideline verbatim); thresholds and workflows change as guidelines update — in practice follow the latest guideline, your institution's protocol and the individual patient.

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