European Journal of Cardiovascular Medicine

Incidental thyroid nodules (ITNs) are defined as thyroid lesions discovered unintentionally during imaging studies performed for unrelated clinical indications. The increasing use of cross-sectional imaging modalities such as computed tomography (CT), magnetic resonance imaging (MRI), and ultrasonography for cervical and thoracic evaluations has led to a significant rise in the detection of ITNs [1,2]. These nodules are typically asymptomatic and non-palpable, yet they present a diagnostic dilemma due to the potential risk of malignancy, particularly papillary thyroid carcinoma [2,4].

The prevalence of ITNs varies widely, reported between 16% and 67%, depending on the imaging modality used, patient population, and institutional protocols [1,3]. CT imaging, in particular, has been associated with a high rate of incidental thyroid findings, though the reporting and follow-up recommendations may vary considerably across radiology subspecialties [3]. This variability in reporting practices underscores the need for standardized guidelines to ensure consistent and clinically relevant evaluation of such findings [4].

Evaluation strategies such as the American College of Radiology Thyroid Imaging Reporting and Data System (ACR TI-RADS) enable structured risk stratification based on ultrasonographic features, helping clinicians determine which nodules warrant further diagnostic workup [4,6]. Additionally, the Bethesda System for Reporting Thyroid Cytopathology standardizes the interpretation of fine-needle aspiration cytology (FNAC) results and guides subsequent clinical decisions [5].

Given the frequency and potential clinical implications of ITNs, this study aims to analyze their imaging characteristics, distribution, and cytological outcomes in patients undergoing neck and chest imaging at a tertiary care center.

This study was conducted to evaluate the imaging characteristics, distribution, and cytological findings of incidentally detected thyroid nodules, and to determine the prevalence of suspicious features that may indicate malignancy. Understanding the profile of ITNs can aid clinicians in making informed decisions regarding their management.

This retrospective observational study was conducted in the Department of Radiology, Government Medical College, Kamareddy, over a period of nine months from May 2024 to January 2025. The study aimed to evaluate the imaging characteristics and clinical significance of incidental thyroid nodules (ITNs) detected during routine neck and chest imaging performed for unrelated clinical indications.

Inclusion Criteria

Patients aged ≥18 years.

Patients who underwent neck CT, chest CT, neck ultrasound, or chest MRI during the study period for non-thyroid-related complaints.

Imaging reports indicating the presence of one or more incidentally detected thyroid nodules.

Exclusion Criteria

Patients with a known history of thyroid disease or prior thyroid surgery.

Patients undergoing imaging specifically for thyroid evaluation.

Incomplete imaging or clinical data in hospital records.

Data Collection

A total of 100 patients who met the inclusion criteria were selected through purposive sampling. Patient demographics (age and sex), imaging modality used, nodule characteristics (location, size, composition), and ultrasonographic features (echogenicity, margins, vascularity, calcifications, shape) were extracted from the radiology reporting system. When available, fine-needle aspiration cytology (FNAC) results and thyroid function tests (TFTs) were also reviewed from patient records.

Nodules evaluated by ultrasound were assessed using standard descriptors and categorized using the American College of Radiology (ACR) TI-RADS system. FNAC results were reported using the Bethesda System for Reporting Thyroid Cytopathology.

Statistical Analysis

Descriptive statistics were used to summarize data. Categorical variables were expressed as frequencies and percentages. The analysis was carried out using Microsoft Excel. No inferential statistics were applied due to the observational nature of the study.

A total of 100 patients were included in this retrospective study evaluating incidental thyroid nodules (ITNs) detected on neck and chest imaging. The mean age of patients was 52.6 ± 13.4 years, with a clear female predominance (68%) (Table 1).

Table 1: Demographic Profile of Patients (n = 100)

Among imaging modalities, CT scans accounted for the highest detection rate of ITNs (52%), followed by neck ultrasonography (31%) and chest MRI (17%) (Table 2a).

Table 2a: Imaging Modalities Used to Detect Incidental Thyroid Nodules

In terms of nodule laterality, 42% were located in the right lobe, 36% in the left lobe, and 22% demonstrated bilateral involvement (Table 2b).

Table 2b: Nodule Laterality

Regarding nodule size, the majority (45%) were in the 1–2 cm range, followed by nodules <1 cm (35%) and >2 cm (20%) (Table 3a).

Table 3a: Distribution of Nodule Size

Solid composition was the most common (54%), with 34% being mixed solid-cystic and 12% purely cystic (Table 3b).

Table 3b: Nodule Composition on Imaging

In the subset of patients (n = 65) who underwent detailed ultrasonographic evaluation, the most frequent echogenic pattern was hypoechoic (43.1%), followed by isoechoic (36.9%) and hyperechoic (20.0%) nodules. Suspicious features included irregular margins (18.5%), microcalcifications (13.8%), increased vascularity (15.4%), and taller-than-wide shape in 9.2% (Table 4).

Table 4: Ultrasound Features of Nodules (n = 65)

Fine Needle Aspiration Cytology (FNAC) was performed in 28 patients based on imaging findings or clinical concern. Most nodules were benign (Bethesda II, 71.4%). Four cases (14.3%) were reported as atypia of undetermined significance (Bethesda III), while 2 cases each were categorized as suspicious for malignancy (Bethesda V) and malignant (Bethesda VI) (Table 5a).

Table 5a: Fine Needle Aspiration Cytology (FNAC) Results (n = 28)

 Histopathological examination following surgery in the malignant cases confirmed papillary thyroid carcinoma.

Evaluation of thyroid function tests (TFTs) revealed that the majority of patients were euthyroid (91%), while 6% had subclinical hypothyroidism and 3% had overt hypothyroidism (Table 5b).

Table 5b: Thyroid Function Test (TFT) Results (n = 100)

This retrospective observational study analyzed 100 patients with incidentally detected thyroid nodules (ITNs) on neck and chest imaging performed for non-thyroid-related clinical indications. The study highlights the frequent occurrence of ITNs, particularly in middle-aged and elderly individuals, with a notable female predominance. This demographic trend is consistent with previous research, which suggests that hormonal influences may contribute to the higher prevalence of thyroid nodules in women [7].

In our cohort, CT scans were the most common modality for detecting ITNs (52%), underscoring the incidental nature of these findings during thoracic and cervical imaging. Although ultrasound remains the gold standard for detailed thyroid assessment, many nodules are first recognized on non-dedicated imaging, necessitating further evaluation [11]. Similar findings have been reported in other studies, which emphasize the incidental detection of thyroid nodules during lung cancer screening and trauma evaluations using CT [8,12].

Most nodules in our study were 1–2 cm in size, and solid in composition (54%), findings that are consistent with published reports showing that the majority of incidentalomas are solid and of intermediate size [9,10]. Among patients who underwent ultrasonography, suspicious features such as hypoechogenicity, microcalcifications, irregular margins, and a taller-than-wide shape were noted. These characteristics have been previously associated with increased risk of malignancy [7,11].

Fine-needle aspiration cytology (FNAC), performed in 28% of patients, revealed that 28.6% of cases had indeterminate or suspicious/malignant cytology. This correlates well with studies indicating that although most ITNs are benign, a small but significant proportion harbor malignancy, most commonly papillary thyroid carcinoma [7,9]. Our findings of malignancy in 3 cases align with this data and reinforce the clinical value of FNAC guided by TI-RADS-based ultrasound risk stratification.

Interestingly, 91% of patients were euthyroid, indicating that ITNs often occur in individuals without clinical or biochemical thyroid dysfunction—a trend observed in similar cohorts [10]. While thyroid function tests (TFTs) may not directly influence the detection of nodules, they remain important for guiding overall thyroid management and surgical planning when required.

Our findings further support the need for standardized imaging and reporting protocols, such as ACR TI-RADS and the Bethesda System, to ensure appropriate follow-up of ITNs and avoid both underdiagnosis and unnecessary interventions. Variability in reporting across radiology subspecialties, as noted in earlier audits, highlights the importance of unified guidelines to minimize inconsistencies [12].

Limitations

The study is limited by its retrospective design, single-center data, and incomplete availability of FNAC and ultrasound details for all patients. Further, lack of long-term follow-up data restricted evaluation of progression in indeterminate nodules.

This study highlights the high prevalence of incidental thyroid nodules (ITNs) detected during routine neck and chest imaging, with most nodules being benign and asymptomatic. A significant proportion displayed radiological features that warranted further evaluation, emphasizing the importance of structured reporting systems like ACR TI-RADS. Fine-needle aspiration cytology helped identify cases of malignancy, reinforcing its role in risk stratification. Most patients were euthyroid, indicating that ITNs often occur in biochemically normal individuals. Early detection and appropriate triaging of ITNs can facilitate timely diagnosis of thyroid malignancies while minimizing unnecessary interventions. Larger prospective studies are recommended to validate these findings and guide evidence-based management strategies.

1. Drake T, Gravely A, Ensrud K, Billington CJ. Reporting of Incidental Thyroid Nodules on Chest Computed Tomography and the Impact on Nodule Evaluation: A Retrospective Cohort Study. Thyroid. 2022 Dec;32(12):1529-1534. doi: 10.1089/thy.2022.0349. Epub 2022 Oct 31. PMID: 36128846.
2. Chaikhoutdinov I, Mitzner R, Goldenberg D. Incidental Thyroid Nodules: Incidence, Evaluation, and Outcome. Otolaryngol Head Neck Surg. 2014 Jun;150(6):939-42. doi: 10.1177/0194599814524705. Epub 2014 Mar 11. PMID: 24618501.
3. Grady AT, Sosa JA, Tanpitukpongse TP, Choudhury KR, Gupta RT, Hoang JK. Radiology reports for incidental thyroid nodules on CT and MRI: high variability across subspecialties. AJNR Am J Neuroradiol. 2015 Feb;36(2):397-402. doi: 10.3174/ajnr.A4089. Epub 2014 Aug 21. PMID: 25147197; PMCID: PMC7965682.
4. Nguyen XV, Choudhury KR, Eastwood JD, Lyman GH, Esclamado RM, Werner JD, Hoang JK. Incidental thyroid nodules on CT: evaluation of 2 risk-categorization methods for work-up of nodules. AJNR Am J Neuroradiol. 2013 Sep;34(9):1812-7. doi: 10.3174/ajnr.A3487. Epub 2013 Apr 4. PMID: 23557957; PMCID: PMC7965620.
5. Bahl M, Sosa JA, Nelson RC, Hoang JK. Imaging-detected incidental thyroid nodules that undergo surgery: a single-center experience over 1 year. AJNR Am J Neuroradiol. 2014 Nov-Dec;35(11):2176-80. doi: 10.3174/ajnr.A4004. Epub 2014 Jun 26. PMID: 24970551; PMCID: PMC7965188.
6. Soto Jacome C, Segura Torres D, Fan JW, Garcia-Bautista A, Golembiewski E, Duran M, Loor-Torres R, Toro-Tobon D, Singh Ospina N, Brito JP. Drivers of Thyroid Ultrasound Use: A Retrospective Observational Study. Endocr Pract. 2023 Dec;29(12):948-954. doi: 10.1016/j.eprac.2023.09.006. Epub 2023 Sep 16. PMID: 37722595; PMCID: PMC10843084.
7. Lansford CD, Teknos TN. Evaluation of the thyroid nodule. Cancer Control. 2006 Apr;13(2):89-98. doi: 10.1177/107327480601300202. PMID: 16735982.
8. Lee JH, Jeong SY, Kim YH. Clinical significance of incidental thyroid nodules identified on low-dose CT for lung cancer screening. Multidiscip Respir Med. 2013 Aug 28;8(1):56. doi: 10.1186/2049-6958-8-56. PMID: 23985215; PMCID: PMC3766674.
9. Uppal A, White MG, Nagar S, Aschebrook-Kilfoy B, Chang PJ, Angelos P, Kaplan EL, Grogan RH. Benign and Malignant Thyroid Incidentalomas Are Rare in Routine Clinical Practice: A Review of 97,908 Imaging Studies. Cancer Epidemiol Biomarkers Prev. 2015 Sep;24(9):1327-31. doi: 10.1158/1055-9965.EPI-15-0292. Epub 2015 Jul 9. PMID: 26160694; PMCID: PMC4560656.
10. Jansen T, Stikkelbroeck N, van de Ven A, van Engen-van Grunsven I, Janssen M, Bonenkamp H, Gotthardt M, Netea-Maier RT. Clinical Characteristics, Diagnostic Approach and Outcome of Thyroid Incidental Findings vs. Clinically Overt Thyroid Nodules: An Observational Single-Centre Study. Cancers (Basel). 2023 Apr 18;15(8):2350. doi: 10.3390/cancers15082350. PMID: 37190278; PMCID: PMC10136807.
11. Bin Saeedan M, Aljohani IM, Khushaim AO, Bukhari SQ, Elnaas ST. Thyroid computed tomography imaging: pictorial review of variable pathologies. Insights Imaging. 2016 Aug;7(4):601-17. doi: 10.1007/s13244-016-0506-5. Epub 2016 Jun 7. PMID: 27271508; PMCID: PMC4956631.
12. 12.Ibrahim A, Parsons M, Taylor J. Thyroid Nodules Detected on CT: A Retrospective Audit Study and Analysis of Differences in Reporting Practices Across Radiology Subspecialties. Curr Probl Diagn Radiol. 2023 May-Jun;52(3):169-174. doi: 10.1067/j.cpradiol.2022.11.003. Epub 2022 Nov 17. PMID: 36481294