Semi-quantitative enhancement curves lifted O-RADS MRI specificity for adnexal masses

Design

Retrospective two-centre diagnostic accuracy study

Population

341 surgically resected adnexal masses in 321 women; 35% malignant

Primary outcome

Accuracy of O-RADS MRI ≥4 for malignancy with visual vs semi-quantitative enhancement assessment

Effect

Specificity 0.84 → 0.92; PPV 0.77 → 0.90; sensitivity 0.95 with visual assessment

O-RADS MRI sorts adnexal masses into those a general gynaecologist can manage and those that need a gynaecological oncologist. Its enhancement assessment is usually visual. This retrospective two-centre study compared visual assessment with a semi-quantitative intensity curve (SIC) — a modified, manually drawn version of the time-intensity curve — in 341 surgically resected masses in 321 women, 35% of them malignant.

With visual assessment, O-RADS MRI had sensitivity 0.95 (0.89 to 0.98), specificity 0.84 (0.79 to 0.89) and positive predictive value 0.77. Using the SIC raised specificity to 0.92 (0.88 to 0.95) and PPV to 0.90 (0.83 to 0.95). The authors report that fewer benign lesions would have been routed to gynaecological oncology. Inter- and intra-reader agreement was moderate to high (κ 0.63 to 0.85).

This matters where oncological surgical capacity is scarce, as in much of India: fewer benign masses referred means shorter waits for women who do have cancer. The curve needs dynamic contrast sequences with adequate temporal resolution, which should be part of any O-RADS MRI protocol.

• Acquire dynamic contrast-enhanced sequences in every O-RADS MRI protocol so a curve can be drawn.
• Plot the enhancement of the solid component over time against the O-RADS reference tissue, as the standard time-intensity method does.
• Use the curve rather than visual impression when assigning the enhancement category for a solid component.
• Report the O-RADS score explicitly, with the management pathway it implies.
• Audit your own benign-to-oncologist referral rate against surgical histology.

Why it matters

Better specificity could keep benign masses off scarce oncology theatre lists.

Don't overread it

Retrospective, surgically selected lesions from two referral centres; the benefit may be smaller in unselected practice.

The statistics, in plain English

Positive predictive value is the chance a mass called suspicious is actually malignant. Rising from 0.77 to 0.90 means roughly one in ten 'suspicious' calls was wrong instead of one in four.

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