Classification of ACR TIRADS 2017 in ultrasound assessment of thyroid nodules


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Up to 67% of the population will have an incidental thyroid nodule when evaluated by ultrasound.

The high prevalence of thyroid nodules associated with the development of thyroid cancer generally presents a challenge for optimal patient care.

The American College of Radiology (ACR) Thyroid Imaging Data and Reporting System (TI-RADS) was created in 2017 with the aim of reducing biopsies of benign nodules and improving overall diagnostic accuracy.

The article has 5 sections and deals with the 2017 ACR TIRADS classification

1. TI-RADS categories (TI-RADS categories)

The five ultrasound features of the thyroid nodules used in TI-RADS are: composition, echogenicity, shape, contour, and dense echogenic spots. Each item is scored.

Scores are added from all components to determine the level of TI-RADS, each with a recommendation.

Nodules smaller than 5 mm do not need monitoring, even if they are TI-RADS 5.
This is because it is very unlikely that nodules smaller than 5 mm will become a clinically significant malignancy.

The 2.5 cm cut-off point for fine-needle aspiration (FNA) in TR3 lesions is less suspicious based on studies that suggest that thyroid carcinomas do not reduce survival until they reach this threshold value.

The ACR-TIRADS category has been shown to correlate with malignancy risk in large studies.

The risk of malignancy is:

TR1: 0.3%
TR2: 1.5%
TR3: 4.8%
TR4: 9.1%
TR5: 35%

There are some exceptions for TI-RADS in which this system cannot be used. Each of these exceptions carries a higher risk of developing thyroid cancer than the average adult:

FDG-PET .-affective thyroid nodules
Known risk factors for thyroid malignancy, such as MEN type 2


Cystic or almost completely cystic lesions are benign and will not add any score (TI-RADS 1). The same is true for sponge-like lesions that are always benign and do not require further sonographic characterization.

This is a typical cyst.
No further evaluation needed.

Sponge form
Sponge nodules have a sponge-like appearance, with at least 50% of the cystic component being very small cystic fractions.
No further specification is required.

Follicle/condensed mixture
In mixed cystic/solid lesions, the number of cystic and solid sections is not important. This lesion scores 1 for the mixed cystic/solid component.

Special injury
Lesions in A are almost entirely solid. Although the nodule contains small cystic components, it is not considered a sponge nodule, as the small cystic portions are much smaller than 50% of the nodule.

The lesion in B is completely solid. In solid nodules, at least 95% of nodules should be solid. This percentage should be an estimate, it does not need to be calculated.



The acoustic drum lesion must be completely black, which means it is cystic. No further specification is required.

Echogenicity was compared with normal thyroid parenchyma.

Both hyperechoic and homonymous lesions receive 1 point, so the score is about the same.
Hypoechoic means that the lesion is hypoechoic than normal thyroid parenchyma. If reverberation cannot be determined, e.g. due to gross calcification, 1 point is calculated for reverberation.

A very hypoechoic lesion is more hypoechoic than normal muscle. Note that the tumor is more hypoechoic than the suspensory muscle (arrow).


The shape should be evaluated in the cross-sectional plane.
Shape higher than width is a strong predictor of malignancy, and is therefore scored 3.


The edge is usually best judged on the front.

Smooth: The edge is completely smooth.

Unknown: nodular margin cannot be clearly defined with thyroid parenchyma. This is a benign feature and should be distinguished from an irregular shoreline.

Multi-lobed or irregular: lobed margins, spines, irregular or angled.

Extra-thyroid enlargement (Invasion beyond the thyroid): difficult to analyze on ultrasound, so there is obvious invasion of adjacent structures. Nodular protrusion in adjacent structures is not sufficient.

Unknown shore
Note that only a small portion of the node’s border can be identified (arrows).
Most of the border is not clear with thyroid parenchyma.
0 points in TI-RADS.

A nodule with irregular margins, angled.
2 points TI-RADS.

The image shows an irregular multilobed margin on the anterior surface.
2 points in TI-RADS.

There is a protruding nodule with compression of nearby structures.
However, there is no obvious invasion, so this is not classed as extrathyroidal invasion.

Echogenic foci

Comet tail artifact, gross calcifications, rim calcifications, microcalcifications (thick echoes flecks)

Thick reverb blobs is the only category that can have multiple options, and you must select all that match. Points will be added to the total score. This means that when both dense echogenic speckles and rim calcifications are present, the TI-RADS score is 2 + 1 = 3 points.

0 points are given for:
No echo spots.
Large comet tail artifact > 1 mm.

Crude calcification
This nodule has a large gross calcification with echogenic shadow. TI-RADS: 1 point.

Edge calcification
Marginal calcifications may or may not be complete. TI-RADS: 2 points.

Thick, mottled echogenic spots are also known as microcalcifications. They are a strong predictor of malignancy and are therefore scored 3.

The term ACR further defines this category, because echogenic spots can also be seen in the normal thyroid gland.
Dense, mottled echogenic spots should be included in cases where the pitch is clear and only visible within the nodule.

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Small comet tail artifacts <=1mm in length are also included in this category. TI-RADS: 3 points.

Growth (Growth)
Nodular development according to TI-RADS was also determined and followed the ATA guidelines.

There should be one of two:

  • 20% increase in at least two dimensions of the nodule, with a minimum increment of 2 mm or >=50% or
  • increase in volume >=50%

If there is no change in size for 5 years, the nodule can be considered benign and does not require further follow-up. Comparisons should be made with the oldest available test, not (only) with the last recent study.

If there is growth over time that does not meet the FNA criteria, follow-up should be after 1 year, regardless of TI-RADS type.

Multiple Nodes
When there are many notes, it is not recommended to classify more than 4 notes. FNA is not recommended for more than 2 notes.

In the case of multiple nodules, nodules that meet the TI-RADS FNA criteria should be sampled, not necessarily dominant (large size, clinically palpable/visible) or largest.

Overdiagnosis and Overtreatment

Once the thyroid nodule is discovered, the question of two options remains: is the tumor benign or malignant? Depending on the published series involved, 6%–13% of thyroid nodules are selected as FNAs for malignancy.

The majority of thyroid cancers discovered incidentally are of papillomatous origin. Unlike undifferentiated thyroid cancer, which has a poor prognosis, although it accounts for only 1%–2% of thyroid cancers, responsible for more than half of all cancer deaths, papillary thyroid cancer very benign.

Because papillary form is the predominant and well-differentiated thyroid cancer, the prognosis is quite good, with a reported 30-year survival rate of 95% (1).

Since most of these cancers will never cause symptoms during life, increased diagnostic surveillance is causing overdiagnosis.
The focus of our research should be on detecting a small percentage of thyroid cancers that are active and change life expectancy.

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BS. Vo Thi Thanh Huong

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