ACR TI-RADS: Seven Scoring Pitfalls That Change the Recommendation

ACR TI-RADS looks like it removes judgment from thyroid nodule reporting. Five categories, add up the points, read off the level. In practice, most of the judgment simply moved into the feature assignments — and because the level boundaries are one point apart in places, a single contested call can be the difference between "no FNA" and "FNA".

Here are the assignments where readers most often disagree.

1. Spongiform is over-called

Spongiform scores 0 points for composition, which is the single most generous assignment in the whole system. It takes a nodule that would otherwise score 1 or 2 and zeroes it.

The definition is strict: the nodule must be composed predominantly of small cystic spaces throughout, conventionally more than half its volume. A nodule with a few scattered cystic spaces in a solid background is not spongiform — it is mixed cystic and solid, and it scores 1.

Because the payoff is large, spongiform attracts optimistic assignment. If you find yourself reaching for it, check whether the cystic spaces genuinely dominate.

2. "Very hypoechoic" has a specific reference

Hypoechoic and very hypoechoic are 2 and 3 points respectively, and they are not judged against the same structure.

• Hypoechoic — less echogenic than adjacent thyroid parenchyma.
• Very hypoechoic — less echogenic than the adjacent strap muscle.

Comparing a dark nodule to the parenchyma and calling it very hypoechoic is a common one-point inflation. Put the strap muscle in the field of view and compare directly.

3. Taller-than-wide is a transverse measurement

Three points, and it is measured on a transverse image, comparing the anteroposterior dimension with the transverse dimension. Assessing shape on a longitudinal image gives a different answer and is not what the criterion means.

This is one of the higher-scoring single features, and it is binary — there is no partial credit — so it deserves a deliberate look rather than an impression.

4. Echogenic foci are additive, and only echogenic foci

Four of the five categories contribute exactly one value. Echogenic foci is the only additive category. A nodule with both macrocalcifications and punctate echogenic foci scores 1 + 3 = 4 points from that category alone.

This is easy to miss when working from memory, and it is the most common source of an under-scored nodule.

5. Punctate echogenic foci versus comet-tail artifact

Punctate echogenic foci score 3 — the highest of any focus type. Large comet-tail artifacts score 0.

They can look similar at a glance and mean opposite things. Comet-tail artifact in a cystic space is inspissated colloid, a benign finding. Punctate echogenic foci in a solid nodule raise concern for psammomatous calcification. Distinguishing them is a 3-point swing, which is enough to move a nodule from TR3 to TR5.

6. The TR3 size threshold surprises people

The FNA thresholds do not scale smoothly:

A TR3 nodule needs to reach 2.5 cm before FNA is recommended. Readers who remember "1.5 cm" as the FNA threshold are remembering TR4. A 2 cm TR3 nodule gets follow-up, not a needle — a call that often surprises the referring clinician, so it is worth stating the level and the threshold explicitly rather than just the recommendation.

7. Know when TI-RADS does not apply

ACR TI-RADS is validated for adults. It is not a paediatric system, and paediatric thyroid nodules carry a materially different malignancy risk that the point thresholds do not reflect.

It also assumes you are characterising a nodule, not following a known entity. A nodule with prior benign cytology, or one being followed after treatment, is a different clinical question.

The one-point total

If you score a nodule at exactly 1 point, the published table appears to skip it — TR1 is labelled 0 points and TR2 is labelled 2 points. A 1-point total falls into the not-suspicious band and is reported as TR2. Worth knowing so it does not stall you mid-report.

Score it without the chart

Our free ACR TI-RADS calculator has all five categories with the point values visible, handles the additive echogenic foci correctly, and applies the size thresholds once you enter a maximum diameter. The full level table is on the page.

To have the level and the FNA recommendation written into the report as you dictate, that is what MyRadAgent does.

Reporting the result

State the points, the level, and the threshold you applied — "solid, hypoechoic, wider-than-tall, smooth margin, punctate echogenic foci: 7 points, TR5. At 12 mm this exceeds the 10 mm FNA threshold; FNA recommended." A future reader can check that. "Suspicious nodule, recommend FNA" cannot be checked at all.