Open Journal of Radiology, 2013, 3, 103-107
http://dx.doi.org/10.4236/ojrad.2013.33016 Published Online September 2013 (http://www.scirp.org/journal/ojrad)
Reliability of Thyroid Imaging Reporting and Data Sys tem
(TIRADS) Classification in Differentiating Benign from
Malignant Thyr oid Nodules*
Boniface Moifo1#, Emmanuel Oben Takoeta1,2, Joshua Tambe1, François Blanc2,
Joseph Gonsu Fotsin1
1Department of Radiology and Radiation Oncology, Faculty of Medicine and Biomedical Sciences,
The University of Yaoundé I, Yaoundé, Cameroon
2Centre Hospitalier de Lagny, Marne La Vallée, France
Received July 2, 2013; revised August 2, 2013; accepted August 9, 2013
Copyright © 2013 Boniface Moifo et al. This is an open access article distributed under the Creative Commons Attribution License,
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Background: Ultrasonography (US) is the best diagnostic tool in the initial assessment of thyroid nodule. Giving its
appropriateness and accessibility, ultrasound-based thyroid imaging reporting and data systems (TIRADS) classifica-
tions have been d eveloped with main goal to standard ize reporting and facilitate communication b etween practitioners,
and to indicate when fine-needle aspiration biopsy (FNAB) should be performed. Objective: To determine the reliabil-
ity of Russ’ modified TIRADS classification in predicting thyroid malignancy. Materials and Methods: It was a cros s
sectional study carried out at Centre Hospitalier de Lagny, Marne La Vallée (France). Consecutive records of patients
with focal thyroid nodules on ultrasound (US) for which US-guided FNAB was performed and pathology results were
available, from January 200 7 to August 2012, were selected for review. The risk of malignan cy of each TIRADS cate-
gory was determined and correlation with pathology assessed. Statistical performances of some US features were also
assessed. The threshold for statistical significance was set at 0.05. Results: A total of 430 records of patients were eligi-
ble. Twenty-three out of 430 (5.3%) nodules were malignant. The risk of malignancy of the TIRADS categories were as
follows: TIRADS2 0%, TIRADS3 2.2%, TIRADS4A 5.9%, TIRADS4B 57.9%, TIRADS 5 100% (Gamma statistic = 0.85;
Spearman correlation = 0.30, Pearson’s R = 0.37, p < 0.001). Some US features were associated with a higher risk of
malignancy: irregular contours (OR = 22.4), taller-than-wide shape (OR = 19.5), microcalcifications (OR = 15.2), and
marked hypoechogenicity (OR = 12.7). Conclusion: Russ’ modified TIRADS classification is reliable in predicting
thyroid malignancy. More evidence is nevertheless necessary for widespread adoption and use.
Keywords: TIRADS; Thyroid Nodule; Thyroid Cancer; Ultrasonography; Fine-Needle Biopsy
Ultrasonography (US) is widely used in the assessment
of the thyroid gland. Among the different pathologies
that can be depicted and characterized by US are nodules.
Nodules can be benign or malignant. Some studies have
shown that less than 10% of thyroid nodules are malig-
nant [1,2] and that thyroid US depicts nodules in up to
50% to 67% of the population [3-5].
Some US-features are in favor of benignity or malig-
nity, especially when grouped together. Suspicious nod-
ules will require fine-needle aspiration biopsy (FNAB)
for pathology analysis. When should FNAB be per-
formed? Although some guidelines have been proposed
[2,6-8], some confusion still exists as the same nodule
may be classified differently using different guidelines
implying different diagnostic or therapeutic attitudes.
*Competing interests: The authors declare that they have no competing
Authors’ contributions: BM conceived the study and participated in its
design, review of the images, data collection and drafting of the manu-
script. EOT participated in the study design, review of the images, data
collection and statistical analysis. JT participated in the review of the
images, statistical analysis and proof-reading of the manuscript. FB
examined all the patients and participated in data collection. JGF par-
ticipated in the study design and proofreading of the manuscript. All
authors read and app roved the final manuscript.
The terminology “Thyroid Imaging Reporting and
Data System” (TIRADS) was first used by Horvath et al.
, drawing inspiration from the “Breast Imaging and
opyright © 2013 SciRes. OJRad
B. MOIFO ET AL.
Reporting Data System” (BIRADS) of the American
College of Radiology . This was in a bid to stan-
dardize the reporting of results of thyroid US that can be
understood by clinicians and also stratify the risk of ma-
lignancy of a lesion based on the US features of the le-
sion. Horvath et al. described 10 US patterns of thyroid
nodules and related the rate of malignancy according to
the pattern . However, these US patterns were not ap-
plicable to all thyroid nodules and appeared difficult to
use in routine clinical practice. Park et al.  proposed
an equation for predicting the probability of malignancy
in thyroid nodules on the basis of 12 US features. Al-
though this approach makes it possible to stratify n odules
into categories, it can be difficult to assign every thyroid
nodule into the equ ation proposed in clinical practice. To
further achieve a practical tool in the hands of sonogra-
phers in analysing thyroid nodules and to improve com-
munication between radiologists and clinicians, Russ et
al.  proposed a TIRADS classification that was fur-
ther modified after feedback from those who used it .
It is therefore apparent that a highly reliable, repro-
ducible and clinically practical TIRADS classification
will greatly improve communication between clinicians
and radiologists. This will even be more helpful in set-
tings where FNAB is not readily available and so deci-
sions will therefore be based to a great extent on the US
features of the lesions and TIRADS classification as this
implies the potential risk for malignancy. It is against this
background that this study was designed to assess the
reliability of the modified TIRADS classification pro-
posed by Russ et al.  in risk stratification for malig-
nancy in a group of patients who had FNAB performed
on some focal thyroid nodules.
2. Materials and Methods
It was a cross-sectional descriptive and analytical study
carried out at Centre Hospitalier de Lagny, Marne La
Vallée (France) from July 2012 to January 2013 with
retrolective data collection. Authorization for the study
was obtained from the local hospital authorities. Con-
secutive records of all patients from January 2007 to
August 2012 with focal thyroid nodules on ultrasound
(US) for which US-guided fine-needle aspiration biopsy
(FNAB) was performed and pathology results were
available were selected for review. All records without
available digital thyroid US images and those with inde-
terminate cytology/histology were excluded.
2.1. Imaging and Imaging Analysis 
All US scans of the thyroid gland and neck areas were
performed using a linear-array transducer (5 - 12 MHz)
on a Philips US scanner (iU22 Philips Medical Systems,
Bothell, Wash) using an optimized gain. One radiologist
with more than ten years of experience performed all of
the thyroid US scans.
All thyroid nodules were characterized according to
the internal component (solid, mixed or cystic), the mar-
gins, echogenicity, evidence of calcifications and the shape.
Margins were classified as well circumscribed, lobulated
or irregular. Echogenicity was classified as “hyperecho-
genicity”, “isoechogenicity”, “hypoechogenicity” and
“marked hypoechogenicity”. Isoechogenicity was de-
fined as an echogenicity similar to that of the adjacent
healthy thyroid gland. A nodule was classified as “marked
hypoechogenicity” if the echogenicity was less than that
of the superficial surrounding neck muscles. When pre-
sent, calcifications were categorized as micro-calcifica-
tions (< 3 mm) and macrocalcifications (> 3 mm with
acoustic shadowing). The shape of the nodule was cate-
gorized as “taller-than-wide” (greater in its antero-poste-
rior dimension than in its transverse dimension) and
Using the modified Russ classification , each nod-
ule was classified into a TIRADS category (1, 2, 3, 4A,
4B and 5) based on the US features.
2.2. US-Guided FNAB
After US evaluation of the thyroid gland, US-guided
FNAB was performed by the same radiologist who per-
formed the US scan. US-guided FNAB was performed
with a 23-gauge needle attached to a 10ml disposable
plastic syringe. Materials obtained from aspiration biopsy
were expelled onto glass slides, smeared and sent to the
pathology laboratory. Cytopathologists of the hospital
specializing in thyroid pathology interpreted the smears.
During the study period, the cytology reports were clas-
sified as benign, indeterminate, suspicious for carcinoma,
malignant, or inadequate. Histology was performed if
cytology was indeterminate or suggestive of malignancy.
TIRADS classification algorithm from Russ classifica-
tion  is showed in Figure 1.
2.3. Data Collection and Analysis
A standardized form was used to collect data. Sensitivity,
specificity, positive predictive value (PPV) and negative
predictive value (NPV) were calculated for each of the
“major” US features that highly suggest malignancy (ir-
regular contours, taller-than-wide, presence of microcal-
cifications, marked hypoechogenicity) according to
Kwak JY et al.  and Kim E-Y et al. . Risk estimates
(odds ratio) were calculated and presented using 95%
confidence interval (CI) statistic. The risk of malignancy
of each TIRADS category was determined. Symmetric
measures (ordinal by ordinal gamma statistic, Spearman
correlation and Pearson’s rho) were used to assess the
strength of the linear relationship between the benign and
Copyright © 2013 SciRes. OJRad
B. MOIFO ET AL. 105
Figure 1. TIRADS classification algorithm .
the malignant groups with respect to the TIRADS ca-
tegories. The threshold for statistical significance was set
at 0.05. All statistical analysis was performed using the
software IBM SPSS 20.0 (SPSS Inc, Chicago, USA).
A total of 430 records of patients who fulfilled the in-
clusion criteria were selected for the study. Twenty-three
out of 430 (5.35%) n odules were h istologically prov en to
3.1. TIRADS Categories, Cytology Results and
Risk of Malignancy
The US features of each thyroid nodule were character-
ized and classified into different TIRADS categories, as
shown in Figure 2. The TIRADS 3 category was domi-
nant, accounting for 226 cases (52.6%).
The different TIRADS categories were confronted
with the results of pathology and the risk of malignancy
was calculated (Table 1). The risk of malignancy was
found to increase from TIRADS 3 to 5. Computed sym-
metric statistics for the strength of association between
benign and malignant cytology results in the different
TIRADS categories were found to be statistically sig-
nificant (p < 0.001).
Combining TIRADS 2, 3 and 4A as probably benign
US findings, and TIRADS 4B and 5 as probably malig-
nant US findings as shown in Table 2, the sensitivity,
specificity, positive pr edictive value and negativ e predic-
tive value were respectively 98.03%, 52.17%, 97.32%
and 60%. The overall accuracy of ul trasound was 95.58%.
Figure 2. TIRADS categories of the study population.
Table 1. TIRADS categories and risk of malignancy.
category BenignMalignant Total Risk of malignancy
TIRADS 2 83 0 83 0
TIRADS 3 221 5 226 2.2
TIRADS 4A95 6 101 5.9
TIRADS 4B8 11 19 57.9
TIRADS 5 0 1 1 100
Total 407 23 430 -
Symmetric measures: Gamma statistic = 0.85 (p < 0.001); Spearman corre-
lation = 0.30 (p < 0.001); Pearson’s R = 0.37 (p < 0.001).
Table 2. TIRADS categories and diagnostic performance of
TIRADS category Benign Malignant Total
TIRADS 2, 3, 4A 399 11 410
TIRADS 4B, 5 8 12 20
Total 407 23 430
3.2. “Major” Ultrasound Findings
The “major” US features suggestive of malignancy were
analyzed with respect to TIRADS categ ories. Sensitivity,
specificity, positive predictive value, negative predictive
value and odds ratio were calculated for each feature.
Tables 3 and 4 show the different statistical analysis of
the major US features with respect to cytology/histology
results, and their respective performance.
A summary of the major US features suggestive of
malignancy are presented in Table 4 alongside their re-
The acronym TIRADS seems to have come to stay. It
harmonizes the reporting of thyroid US findings in a very
simply way that facilitates comprehension across differ-
ent specialties. For any such classification system to be
Copyright © 2013 SciRes. OJRad
B. MOIFO ET AL.
Table 3. Major US features and pathology results.
Major ultrasound features Benign Malignant Total
Present 2 8 10
Irregular margins Absent 405 15 420
Present 0 1 1
shape Absent 407 22 429
Present 5 7 12
Microcalcification Absent 402 16 418
Present 2 3 5
hypoechogenicity Absent 405 20 425
Irregular margins: odds ratio for benign cytology: 0.21 (95%CI: 0.06 -
0.72). Odds ratio for malignant cytology: 22.40 (95%CI: 12.47 - 40.23).
Taller-t han-wide shape : odds ratio for malignant cytology: 19.50 (95%CI:
12.98 - 29.25). Microcalcification: odds ratio for benign cytology: 0.43
(95%CI: 0.22 - 0.85). Odds ratio for cytology: 15.24 (95%CI: 7 .74 - 30.02).
Marked hypoechogenicity: odds ratio for benign cytology: 0.42 (95%CI:
0.14 - 1.23). Odds ratio for malignant cytology: 12.75 (95%CI: 5.54 -
Table 4. Summary of the statistical performance of the ma-
jor US features.
US feature Se (%) Sp (%) PPV
Irregular contours 34.78 99.51 80 96.4322.40
shape 4.35 100 100 94.8719.50
Microcalcification 30.4 98.8 58.3 96.2 15.24
hypoechogenicity 13.04 99.51 60 95.2912.75
Se = Sensitivity; Sp = Specificity; PPV = Positive Predictive Value; NPV =
Negative Predictive Value; OR = Odd Ratio.
useful for routine clin ical practice, it should be simple to
use, reproducible and very reliable.
Thyroid cancer is a relatively rare entity, with an esti-
mated prevalence of about 5% [4,5,14]. The proportion
of malignant thyroid nodules obtained in this study was
similar to this value. A high accuracy of any classifica-
tion in predicting malignant thyroid lesions will be par-
ticularly of help in resource-limited setting s where p atho-
logical analysis is not routinely performed even when
confronted with some suspiciously malignant lesions.
The diagnostic accuracy of US in this study exceeded to
that obtained by Moon et al.  in 2002.
From our results, the risk of malignancy significantly
increased from TIRADS 3 to 5. This was zero for TI-
RADS 2, and would be expected to be so since TIRADS
2 is considered ultraso nographically as a typically b enign
lesion. In his work, Horvath suggested a malignant risk
of less than 5% for TIRADS 3, 5% to 10% for TIRADS
4A, 10% to 80% for TIRADS 4B and greater than 80%
for TIRADS 5 . Our findings are within this range
suggested by Horvath and similar to that obtained by
Russ et al. . This is capital in risk stratification for
malignancy of thyroid nodules. So if properly classified
on US the probability of a particular nodule being ma-
lignant can be inferred from the TIRADS category with a
certain level of confidence and appropriate measures for
management can be initiated.
Most cancers were found in the TIRADS 3, 4A and 4B
categories. We can infer from this that most cancers will
have US features that may seem probably benign ultra-
sonographically, or have features that mimic a low or a
high suspicion for malignancy. So very few cases of ma-
lignancy will have the very typical ultrasound features
that are consistent with malignancy. This further justifies
the advocacy for FNAB when lesions are not typically
The presence of some US features had earlier been
described as highly suspicious for malignancy, and they
include marked hypoechogenicity, taller-than-wide shape,
irregular contours and the presence of calcifications [5, 6,
12]. In our study, these features were found to be highly
suspicious for malignancy as can be seen from the odds
ratios, sensitivities, specificities, PPV and NPV. How-
ever we did not assess the probabilities of malignancy o f
associated features, which was found to increase in a
previous stud y . In one study Hong YJ et al.  con-
cluded that the three sonographic features that are mean-
ingful findings in the diagnosis of thyroid malignancy
were the presence of microcalcifications, marked hypo-
echogenecity and a taller-th an-wide shape. In a multicen-
tre Korean r etrospective study, the US features that w ere
statistically significant for malignant thyroid nodules
were hypoechogenicity, marked hypoechogenicity, non-
parallel orientation, microlobulated or speculated margin,
ill-defined margins and the presence of micro-calcifica-
tions . In the latest study, 7.3% of malignant nodules
did not ha ve suspiciou s-maligna nt features o n U S.
This study has not been void of limitations, which in-
clude retrolective data collection and the fact that his-
tology was not available for all of the thyroid nodules, as
those with a benign cytology were not operated for ethi-
cal reasons. However, this can be compensated by the
high NPV of cytology .
Russ’ modified TIRADS classification is reliable in pre-
dicting thyroid malignancy. We therefore advocate for
further studies in the same light for more evidence and
the validation of a classification system for the thyroid
gland that will be simple to use, reliable, reproducible
and facilitate communication across different clinical spe-
Copyright © 2013 SciRes. OJRad
B. MOIFO ET AL.
Copyright © 2013 SciRes. OJRad
The authors wish to thank the tea m of the Patho logy De-
partment of the Centre Hospitalier de Lagny, Marne La
Vallée (France) for helping with cytology/histology re-
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