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ORIGINAL ARTICLE HEALTH SERVICES RESEARCH AND POLICY ACR Thyroid Imaging, Reporting and Data System (TI-RADS): White Paper of PDF

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ORIGINAL ARTICLE

HEALTH SERVICES RESEARCH AND POLICY

ACR Thyroid Imaging, Reporting and Data
System (TI-RADS): White Paper of the
ACR TI-RADS Committee
Franklin N. Tessler, MD, CM a , William D. Middleton, MD b, Edward G. Grant, MD c,
Jenny K. Hoang, MBBS d, Lincoln L. Berland, MD a, Sharlene A. Teefey, MD b, John J. Cronan, MD e,
Michael D. Beland, MD e, Terry S. Desser, MD f, Mary C. Frates, MD g, Lynwood W. Hammers, DO h,i,
Ulrike M. Hamper, MD j, Jill E. Langer, MD k, Carl C. Reading, MD l, Leslie M. Scoutt, MD m,
A. Thomas Stavros, MD n
Abstract
Thyroid nodules are a frequent finding on neck sonography. Most nodules are benign; therefore, many nodules are biopsied to identify
the small number that are malignant or require surgery for a definitive diagnosis. Since 2009, many professional societies and investigators have proposed ultrasound-based risk stratification systems to identify nodules that warrant biopsy or sonographic follow-up.
Because some of these systems were founded on the BI-RADS classification that is widely used in breast imaging, their authors chose to
apply the acronym TI-RADS, for Thyroid Imaging, Reporting and Data System. In 2012, the ACR convened committees to (1) provide
recommendations for reporting incidental thyroid nodules, (2) develop a set of standard terms (lexicon) for ultrasound reporting, and (3)
propose a TI-RADS on the basis of the lexicon. The committees published the results of the first two efforts in 2015. In this article, the
authors present the ACR TI-RADS Committee’s recommendations, which provide guidance regarding management of thyroid nodules
on the basis of their ultrasound appearance. The authors also describe the committee’s future directions.
Key Words: Thyroid nodule, thyroid cancer, management guidelines, ultrasound
J Am Coll Radiol 2017;-:---. Copyright  2017 American College of Radiology

INTRODUCTION
Thyroid nodules are exceedingly common, with a reported
prevalence of up to 68% in adults on high-resolution
ultrasound [1]. Currently, fine-needle aspiration (FNA)

is the most effective, practical test to determine whether a
nodule is malignant or may require surgery to reach a
definitive diagnosis [2]. However, most nodules are
benign, and even malignant nodules, particularly ones

a
Department of Radiology, University of Alabama at Birmingham,
Birmingham, Alabama.
b
Mallinckrodt Institute of Radiology, Washington University School of
Medicine, St Louis, Missouri.
c
Department of Radiology, Keck School of Medicine, University of
Southern California, Los Angeles, California.
d
Department of Radiology, Duke University School of Medicine, Durham,
North Carolina.
e
Department of Diagnostic Imaging Brown University, Providence, Rhode
Island.
f
Department of Radiology, Stanford University Medical Center, Stanford,
California.
g
Department of Radiology, Brigham and Women’s Hospital, Boston,
Massachusetts.
h
Hammers Healthcare Imaging, New Haven, Connecticut.
i
Department of Internal Medicine, Yale School of Medicine, New Haven,
Connecticut.

j

Department of Radiology and Radiological Science, Johns Hopkins
University, School of Medicine, Baltimore, Maryland.
k
Department of Radiology, University of Pennsylvania, Philadelphia,
Pennsylvania.
l
Department of Radiology, Mayo Clinic College of Medicine, Rochester,
Minnesota.
m
Department of Radiology and Biomedical Imaging, Yale University, New
Haven, Connecticut.
n
Department of Radiology, University of Texas Health Sciences Center,
San Antonio, Texas.
Corresponding author and reprints: Franklin N. Tessler, MD, CM,
Department of Radiology, University of Alabama at Birmingham,
Birmingham, AL 35249; e-mail: ftessler@uabmc.edu.
Dr Berland received personal fees from Nuance Communications during
the conduct of the study. Dr Beland has received personal fees from Hitachi
Aloka America outside the submitted work. All other authors have no
conflicts of interest related to the material discussed in this article.

ª 2017 American College of Radiology
1546-1440/17/$36.00 n http://dx.doi.org/10.1016/j.jacr.2017.01.046

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1

smaller than 1 cm, frequently exhibit indolent or
nonaggressive behavior [3-5]. Therefore, not all detected
nodules require FNA and/or surgery.
Despite a rapid increase in the reported incidence of
papillary thyroid cancer that resulted from screening
thyroid sonography in asymptomatic patients in South
Korea, mortality has remained extremely low [6]. In the
United States, overdiagnosis of thyroid cancer, defined
as “diagnosis of thyroid tumors that would not, if left
alone, result in symptoms or death” accounted for 70%
to 80% of thyroid cancer cases in women and 45% of
cases in men between 2003 and 2007 [7].
Therefore, a reliable, noninvasive method to identify
which nodules warrant FNA on the basis of a reasonable
likelihood of biologically significant malignancy would be
highly desirable. In 2015, committees convened by the
ACR published white papers that presented an approach to
incidental thyroid nodules and proposed standard terminology (lexicon) for ultrasound reporting [8,9]. The
purpose of the present white paper is to present our
system for risk stratification, which is designed to identify
most clinically significant malignancies while reducing the
number of biopsies performed on benign nodules.

PROJECT RATIONALE AND CONSENSUS
PROCESS
Several professional societies and groups of investigators
have proposed methods to guide ultrasound practitioners
in recommending FNA on the basis of ultrasound features
[10-18]. Some of these systems were termed TI-RADS
(Thyroid Imaging, Reporting and Data System) because
they were modeled on the ACR’s BI-RADS, which has been
widely accepted in breast imaging. Other societies, such as the
American Thyroid Association (ATA), have taken a slightly
different, pattern-oriented approach, but with the same
intent [19]. The plethora, complexity, and lack of congruence
of these systems has limited their adoption by the ultrasound
community and inspired our effort to publish a classification
system under the auspices of the ACR. The ACR TI-RADS
Committee agreed on the following attributes for our risk
classification algorithm. It would be:
n

n

n
n

founded on the ultrasound features defined in our
previously published lexicon;
easy to apply across a wide gamut of ultrasound
practices;
able to classify all thyroid nodules; and
evidence based to the greatest extent possible.

The proposals presented in this white paper, which
were developed via conference calls, e-mail, and online
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surveys, represent the consensus opinion of the ACR TIRADS Committee. They are based on the literature;
analysis of data from the Surveillance, Epidemiology, and
End Results (SEER) Program of the National Cancer
Institute; evaluation of existing risk classification systems;
and expert opinion. Our recommendations are intended to
serve as guidance for practitioners who incorporate ultrasound in the management of adult patients with thyroid
nodules. They should not be construed as standards.
Interpreting and referring physicians are legally and professionally responsible for applying their professional
judgment to every case, regardless of the ACR TI-RADS
recommendations. The decision to perform FNA should
also account for the referring physician’s preference and the
patient’s risk factors for thyroid cancer, anxiety, comorbidities, life expectancy, and other relevant considerations.

OVERVIEW OF ACR TI-RADS
The ultrasound features in the ACR TI-RADS are categorized as benign, minimally suspicious, moderately
suspicious, or highly suspicious for malignancy. Points are
given for all the ultrasound features in a nodule, with
more suspicious features being awarded additional points.
Figure 1 presents these features arranged per the five
lexicon categories [8]. When assessing a nodule, the
reader selects one feature from each of the first four
categories and all the features that apply from the final
category and sums the points. The point total
determines the nodule’s ACR TI-RADS level, which
ranges from TR1 (benign) to TR5 (high suspicion of
malignancy). Note that although it is possible for a
nodule to be awarded zero points and hence be characterized as TR1, all other nodules merit at least two points
because a nodule that has a mixed cystic and solid
composition (one point) will also gain at least one more
point for the echogenicity of its solid component. Finally,
although sonoelastography is a promising technique
[20,21], it is probably not available in many ultrasound
laboratories and is not incorporated into the ACR TIRADS.
In the ACR TI-RADS, recommendations for FNA or
ultrasound follow-up are based on a nodule’s ACR TIRADS level and its maximum diameter. For risk levels
TR3 through TR5, the chart presents a size threshold at
or above which FNA should be recommended. We also
defined lower size limits for recommending follow-up
ultrasound for TR3, TR4, and TR5 nodules to limit
the number of repeat sonograms for those that are likely
to be benign or not clinically significant.
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ACR TI-RADS
COMPOSITION

ECHOGENICITY

SHAPE

MARGIN

ECHOGENIC FOCI

(Choose 1)

(Choose 1)

(Choose 1)

(Choose 1)

(Choose All That Apply)

Cystic or almost
completely cystic

0 points

Anechoic

0 points

Wider-than-tall

0 points

Smooth

0 points

Spongiform

0 points

Hyperechoic or
isoechoic

1 point

Taller-than-wide

3 points

Ill-defined

0 points

Mixed cystic
and solid

1 point

Hypoechoic

2 points

Lobulated or
irregular

2 points

Solid or almost
completely solid

2 points

Very hypoechoic

3 points

Extra-thyroidal
extension

3 points

None or large
comet-tail artifacts

0 points

Macrocalcifications

1 point

Peripheral (rim)
calcifications

2 points

Punctate echogenic
foci

3 points

Add Points From All Categories to Determine TI-RADS Level

0 Points

3 Points

2 Points

4 to 6 Points

7 Points or More

TR1

TR2

TR3

TR4

TR5

Benign

Not Suspicious

Mildly Suspicious

Highly Suspicious

No FNA

No FNA

FNA if ≥ 2.5 cm
Follow if ≥ 1.5 cm

Moderately Suspicious
FNA if ≥ 1.5 cm
Follow if ≥ 1 cm

COMPOSITION

ECHOGENICITY

SHAPE

Spongiform: Composed predominantly (>50%) of small cystic
spaces. Do not add further points
for other categories.

Anechoic: Applies to cystic or almost
completely cystic nodules.

Mixed cystic and solid: Assign
points for predominant solid
component.

Very hypoechoic: More hypoechoic
than strap muscles.

Taller-than-wide: Should be assessed
on a transverse image with measurements parallel to sound beam for
height and perpendicular to sound
beam for width.

Assign 2 points if composition
cannot be determined because of
calcification.

Hyperechoic/isoechoic/hypoechoic:
Compared to adjacent parenchyma.

Assign 1 point if echogenicity cannot
be determined.

This can usually be assessed by
visual inspection.

MARGIN
Lobulated: Protrusions into adjacent
tissue.
Irregular: Jagged, spiculated, or sharp
angles.
Extrathyroidal extension: Obvious
invasion = malignancy.
Assign 0 points if margin cannot be
determined.

FNA if ≥ 1 cm
Follow if ≥ 0.5 cm*

ECHOGENIC FOCI
Large comet-tail artifacts: V-shaped,
>1 mm, in cystic components.
Macrocalcifications: Cause acoustic
shadowing.
Peripheral: Complete or incomplete
along margin.
Punctate echogenic foci: May have
small comet-tail artifacts.

*Refer to discussion of papillary microcarcinomas for 5-9 mm TR5 nodules.

Fig 1. Chart showing five categories on the basis of the ACR Thyroid Imaging, Reporting and Data System (TI-RADS) lexicon, TR
levels, and criteria for fine-needle aspiration or follow-up ultrasound. Explanatory notes appear at the bottom.

In developing the ACR TI-RADS, the committee
strived to account for the discrepancy between the sharp
rise in the diagnosis and treatment of thyroid cancer
resulting from increased detection and biopsy and the
lack of commensurate improvement in long-term outcomes [22]. This suggested to us that diagnosing every
thyroid malignancy should not be our goal. Like other
professional societies [17,19], we recommend biopsy of
high-suspicion nodules only if they are 1 cm or larger.
As well, we advocate biopsy of nodules that have a low
risk for malignancy only when they measure 2.5 cm or
more.
The ACR TI-RADS is designed to balance the benefit
of identifying clinically important cancers against the risk
and cost of subjecting patients with benign nodules or
indolent cancers to biopsy and treatment. Our recommendations for follow-up ultrasound substantially mitigate the possibility that significant malignancies will
remain undetected over time and are concordant with the
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increasing trend toward active surveillance (“watchful
waiting”) for low-risk thyroid cancer [23,24].

DIFFERENCES BETWEEN ACR TI-RADS AND
OTHER SYSTEMS
Structure
To make the system easy to understand and apply, the
ACR TI-RADS does not include subcategories, nor does
it include a TR0 category to indicate a normal thyroid
gland. The ACR TI-RADS also lends itself to implementation as templates in voice recognition reporting or
computerized decision support systems. The committee
decided against the pattern-based approach used by the
ATA on the basis of the results of a study by Yoon et al
[25], which showed that the ATA guidelines were unable
to classify 3.4% of 1,293 nodules, of which 18.2% were
malignant. Notably, that study included only nodules
that were subjected to FNA or surgery. It is likely that

ACR TI-RADS

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an even greater percentage of nodules would not have
been categorized had other nodules been included, as it
is not practical to provide patterns that account for
every potential constellation of features.

Size Thresholds for FNA
The ACR TI-RADS is consistent with most other guidelines in recommending FNA for highly suspicious nodules
1 cm or larger. However, our thresholds for mildly suspicious and moderately suspicious nodules (2.5 and 1.5 cm,
respectively) are higher than the cutoffs advocated by the
ATA and the Korean Society of Thyroid Radiology [17,19].
In a 2005 publication cited by both organizations,
Machens et al [26] contended that the cumulative risk for
distant metastases from papillary and follicular thyroid
cancer rose at a threshold of 2 cm. They therefore
advocated biopsy of nodules larger than 2 cm.
However, our review of their graphs suggested a
gradual, slight increase that began at a larger size. More
important, Machens et al based their analysis on tumor
size in resected specimens, not on ultrasound
dimensions. Subsequent research has demonstrated a
significant lack of concordance between sonographic
and pathologic sizing, with a tendency for ultrasound to
result in larger measurements [27]. Of 205 papillary
carcinomas 1.5 cm studied by Bachar et al [28], the
mean diameter on ultrasound was 2.65  1.07 cm,
compared with 1.97  1.17 cm on pathology. The
committee’s higher size cutoffs reflect this discrepancy.
Our choices were further guided by evaluation of a
database of more than 3,000 proven thyroid nodules that
was created for a study sponsored by the Society of Radiologists in Ultrasound [29]. Partial analysis showed
cancer risk levels of no more than 2% for TR1 and TR2
nodules, 5% for TR3 nodules, 5% to 20% for TR4
nodules, and at least 20% for TR5 nodules We also
considered published [30] and newly performed SEER
data analyses that showed a slight increase in distant
metastases at 2.5 cm, as well as slight increments in 10year relative and thyroid cancer-specific mortality at 3 cm.
ACR TI-RADS FEATURE CATEGORIES
In this section, we elaborate on the five groups of ultrasound findings, ACR TI-RADS levels, and size thresholds. Readers are encouraged to refer to the lexicon white
paper for detailed descriptions of all the categories and
features [8]. As well, any history of prior FNA or ethanol
ablation should be sought, as these procedures may lead
to a suspicious appearance at follow-up ultrasound [31].
4

Composition
Nodules that are cystic or almost completely cystic merit
no points because they are almost universally benign [16].
Similarly, a spongiform architecture is highly correlated with benign cytology, regardless of its relative
echogenicity or other features [32-34]. However, a
spongiform nodule must be composed predominantly
(>50%) of small cystic spaces [8]. Nodules should not
be characterized as spongiform solely on the basis of the
presence of a few, scattered cystic components in an
otherwise solid nodule (Online Fig. 2).
“Mixed cystic and solid” combines two features from the
lexicon, predominately solid and predominately cystic. The
appearance of the solid component is more important than
the overall size of the nodule or the proportion of solid versus
cystic components in determining whether biopsy is warranted. Solid material that is eccentric and has an acute angle
with the nodule’s wall is suspicious, as is solid material with
moderately or highly suspicious characteristics, such as
decreased echogenicity, lobulation, and punctate echogenic
foci [35-38]. As well, although color Doppler ultrasound has
not been shown to reliably discriminate between benign and
malignant nodules [39], the presence of flow in solid
components distinguishes tissue from echogenic debris or
hemorrhage. Inconsequential debris may be identified by
layering or motion elicited by changes in patient position.
Echogenicity
This feature refers to a nodule’s reflectivity relative to
adjacent thyroid tissue, except for very hypoechoic nodules, in which the strap muscles are used as the basis for
comparison. This category also includes “anechoic,” a
zero-point feature that was absent from the lexicon. It
applies to cystic or almost completely cystic nodules that
would otherwise be given three points because of their
very hypoechoic appearance.
Shape
A taller-than-wide shape is an insensitive but highly
specific indicator of malignancy [12,13,40]. This feature
is evaluated in the axial plane by comparing the height
(“tallness”) and width of a nodule measured parallel and
perpendicular to the ultrasound beam, respectively.
A taller-than-wide configuration is usually evident on
visual inspection and rarely requires formal measurements.
Margin
The presence of a halo is neither discriminatory nor
mutually exclusive with other margin types; therefore, we
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elected to omit it. We included “ill defined” in this group
so that any reporting template that incorporates a field for
margin will not be left empty if a nodule is not well
defined. “Lobulated or irregular margin” refers to a spiculated or jagged edge, with or without protrusions into
the surrounding parenchyma. It may be difficult to
recognize this finding if the nodule is ill defined, is
embedded in a heterogeneous gland, or abuts multiple
other nodules. If the margin cannot be determined for
any reason, zero points should be assigned.
Extension beyond the thyroid border is classified as
extensive or minimal [41]. (We use the term border
because the thyroid gland lacks a true fibrous capsule
[42].) Extensive extrathyroidal extension (ETE) that is
characterized by frank invasion of adjacent soft tissue
and/or vascular structures is a highly reliable sign of
malignancy and is an unfavorable prognostic sign [43].
Minimal ETE may be suspected sonographically in the
presence of border abutment, contour bulging, or loss
of the echogenic thyroid border [44,45]. However,
agreement among pathologists for identification of
minimal ETE is poor [46], and its clinical significance
is controversial [41,47,48]. Therefore, practitioners
should exercise caution when reporting minimal ETE,
particularly for otherwise benign-appearing nodules.

Echogenic Foci
“Large comet-tail artifacts” are echogenic foci with V-shaped
echoes >1 mm deep to them. They are associated with
colloid and are strongly indicative of benignity when found
within the cystic components of thyroid nodules. “Macrocalcifications” are coarse echogenic foci accompanied
by acoustic shadowing. Evidence in the literature regarding
their association with increased malignancy risk is
mixed, especially in nodules lacking other malignant
features [12,49-51]. Given published data that show a
weakly positive relationship with malignancy [52],
macrocalcifications are assigned one point, recognizing that
the risk is increased if the nodule also contains moderately
or highly suspicious features that warrant additional points.
Peripheral calcifications lie along all or part of a
nodule’s margin. Their correlation with malignancy in
the literature is variable [49]. However, because some
publications suggest that they are more strongly
associated with malignancy than macrocalcifications,
they are awarded two points [52]. Some authors have
called attention to interrupted peripheral calcifications
with protruding soft tissue as suspicious for malignancy,
but with low specificity [53]. In the ACR TI-RADS,
this appearance qualifies as a lobulated margin, which
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adds another two points to the nodule’s total assignment.
In nodules with calcifications that cause strong acoustic
shadowing that precludes or limits assessment of internal
characteristics, particularly echogenicity and composition,
it is best to assume that the nodule is solid and assign two
points for composition and one point for echogenicity.
Punctate echogenic foci are smaller than macrocalcifications and are nonshadowing. In the solid components of thyroid nodules, they may correspond to the
psammomatous calcifications associated with papillary
cancers and are therefore considered highly suspicious,
particularly in combination with other suspicious features. This category includes echogenic foci that are
associated with small comet-tail artifacts in solid components, as distinguished from the large comet-tail artifacts described earlier [54]. Notably, small echogenic foci
may be seen in spongiform nodules, where they probably
represent the back walls of minute cysts. They are not
suspicious in this circumstance and should not add to
the point total of spongiform nodules.

Additional Benign Appearances
Several ultrasound findings have been described as characteristic of benign nodules with a high degree of reliability. These include a uniformly hyperechoic (“white
knight”) appearance, as well as a variegated pattern of
hyperechoic areas separated by hypoechoic bands reminiscent of giraffe hide, both in the setting of Hashimoto’s
thyroiditis [34]. Because of their scarcity, the committee
chose not to formally incorporate these patterns in the
ACR TI-RADS chart.
PAPILLARY THYROID MICROCARCINOMAS
The ACR TI-RADS is concordant with other guidelines
in recommending against routine biopsy of nodules
smaller than 1 cm, even if they are highly suspicious.
However, because some thyroid specialists advocate active
surveillance, ablation, or lobectomy for papillary microcarcinomas, biopsy of 5- to 9-mm TR5 nodules may be
appropriate under certain circumstances [24,55-57]. The
determination to perform FNA will involve shared
decision making between the referring physician and the
patient. The report should indicate whether the nodule
can be measured reproducibly on follow-up studies.
Additionally, nodules in critical submarginal locations
may complicate surgery [24,55,56]. Therefore, the report
should also indicate whether the nodule abuts the trachea
or whether it is adjacent to the tracheoesophageal groove
(the location of the recurrent laryngeal nerve).

ACR TI-RADS

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5

REPORTING CONSIDERATIONS
Measurement and Documentation
Accurate sizing of thyroid nodules is critical, as the
maximum dimension determines whether a given lesion
should be biopsied or followed. Although some interobserver discrepancy is inevitable because of variable
conspicuity, consistent technique improves measurement
accuracy and reproducibility.
Nodules should be measured in three axes: (1)
maximum dimension on an axial image, (2) maximum
dimension perpendicular to the previous measurement on
the same image, and (3) maximum longitudinal dimension on a sagittal image (Online Fig. 3) [58]. For
obliquely oriented nodules, these measurements may be
different than the ones used to determine a taller-thanwide shape, but this discrepancy should rarely present a
problem in practice. Measurements should also include
the nodule’s halo, if present. Practitioners may use linear
dimensions to determine volume, a calculation that is
available on many ultrasound machines. Regardless of the
method used, each practice should measure and report
nodules consistently to facilitate serial comparison.
Meticulous documentation of the location of nodules
on sonograms is equally important, particularly when the
thyroid gland is heterogeneous or multiple nodules are
present. Every nodule targeted for surveillance should be
numbered sequentially and labeled as to its location in the
thyroid gland (right, left, isthmus, upper, mid, lower,
and, if necessary, lateral, medial, anterior, or posterior).
Ultrasound video clips are valuable to provide further
information about the spatial relationships between
nodules and adjacent structures. The committee recommends that no more than four nodules with the highest
ACR TI-RADS point scores that fall below the size
threshold for FNA should be followed, as detailed
reporting of more than four nodules would needlessly
complicate and lengthen reports. Other nodules may be
reassessed on subsequent sonograms without being
formally enumerated.
The committee did not address follow-up for previously sampled nodules. The decision to request a repeat
biopsy is typically driven by referring physicians and is
guided by management recommendations based on prior
FNA results based on the Bethesda System for Reporting
Thyroid Cytopathology [19,59,60].
Definition of Growth
Criteria for significant growth depend on the size of the
nodule and must take measurement variability into
6

account. In the ACR TI-RADS, significant enlargement
is defined as a 20% increase in at least two nodule dimensions and a minimal increase of 2 mm, or a 50% or
greater increase in volume, as in the criteria adopted by
other professional societies [19]. Because enlargement
may not be apparent if the current sonogram is
compared only with the immediately preceding one, it
is important to also review measurements from earlier
scans, if available.

Timing of Follow-Up Sonograms
There is little consensus in the literature regarding optimal
spacing of follow-up sonograms for nodules that do not
meet size criteria for FNA, as growth rates do not reliably
distinguish benign from malignant nodules [61]. The
committee believes that scanning intervals of less than 1
year are not warranted [62], except for proven cancers
under active surveillance, which may require more
frequent follow-up at the discretion of the referring physician [56]. We advocate timing on the basis of a nodule’s
ACR TI-RADS level, with additional sonograms for lesions that are more suspicious. For a TR5 lesion, we
recommend scans every year for up to 5 years. For a TR4
lesion, scans should be done at 1, 2, 3, and 5 years. For a
TR3 lesion, follow-up imaging may be performed at 1, 3,
and 5 years. Imaging can stop at 5 years if there is no change
in size, as stability over that time span reliably indicates that
a nodule has a benign behavior [63]. There is no published
evidence to guide management of nodules that enlarge
significantly but remain below the FNA size threshold for
their ACR TI-RADS level at 5 years, but continued
follow-up is probably warranted. If a nodule’s ACR TIRADS level increases on follow-up, the next sonogram
should be done in 1 year, regardless of its initial level.
Number of Nodules to Biopsy
Biopsy of three or more nodules is poorly tolerated by
patients and increases cost with little or no benefit and
some added risk. Therefore, the committee recommends
targeting no more than two nodules with the highest
ACR TI-RADS point totals that meet criteria for FNA.
Size should not be the primary criterion for deciding
which nodule(s) to sample. We discourage usage of
the term dominant nodule, which is often applied to the
largest lesion in the gland, because it downplays the
primary role of architecture in determining management.
If three or more nodules fall within ACR TI-RADS
guidelines for biopsy, the two with the most suspicious
appearance on the basis of point totals should be
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biopsied, even if they are not the largest. Conversely, in a
gland that contains multiple discrete nodules that do not
meet criteria, there is little reason to subject the largest
one to FNA solely because of its size. Although malignancy cannot be definitively excluded under these conditions, sampling variation lessens the chance of detecting
cancer because it would be impractical to biopsy every
nodule. Likewise, biopsy is usually not indicated in a
gland that is replaced by multiple, confluent nodules of
similar appearance.

Assessment of Cervical Lymph Nodes
Evaluation of cervical lymph nodes is a vital part of every
thyroid sonographic examination [64]. Abnormal findings
suggestive of cervical lymph node metastasis include a
globular shape, loss of the normal echogenic hilum,
presence of peripheral rather than hilar flow, heterogeneity
with cystic components, and punctate echogenic foci that
may represent microcalcifications. Detailed discussions of
these features and representative ultrasound images are
available elsewhere [65-67]. We recommend FNA of
suspicious nodes, in addition to up to two nodules that
warrant biopsy on the basis of the ACR TI-RADS.
FUTURE DIRECTIONS
The committee believes that the ACR TI-RADS meets
our stated goals, although acknowledging the limitations
of our additive approach, which does not fully account
for the possibility that the risk conferred by a given ultrasound feature may vary depending on what other
features are present in a nodule. As well, several committee members have embarked on a parallel project in
which interobserver variability of ultrasound feature
assignment will be measured. We plan to revise the ACR
TI-RADS periodically as results from this study and other
evidence comes to light.
TAKE-HOME POINTS
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-

-

The goal of this project is to define a risk stratification system for thyroid nodules (ACR TI-RADS)
to guide decisions regarding FNA and follow-up.
The ACR TI-RADS chart allows practitioners to
assign points to nodules based on ultrasound features from a standardized lexicon that lends itself to
structured reporting.
The features that form the basis of this system will
be assessed for inter-observer variability in a parallel
project.

Journal of the American College of Radiology
Health Services Research and Policy n Tessler et al

n

ACKNOWLEDGMENTS
The authors thank Dr Herbert Chen, chair of the
Department of Surgery at the University of Alabama at
Birmingham, for reviewing the manuscript. We also are
grateful to Dr Xuan V. Nguyen of Ohio State University
for performing the SEER data analysis.
ADDITIONAL RESOURCES
Additional resources can be found online at: http://dx.
doi.org/10.1016/j.jacr.2017.01.046.
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Journal of the American College of Radiology
Health Services Research and Policy n Tessler et al

n

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ACR TI-RADS

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9

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