European Journal of Cardiovascular Medicine

Thyroid nodules are a common clinical finding, particularly among adults, with a higher prevalence observed in women and the elderly. While palpation can detect nodules in approximately 4–7% of the population, the use of high-resolution ultrasound has revealed that up to 67% of people may have thyroid nodules [1, 2].

Thyroid nodules (TNs) are abnormal growths that can be easily identified through imaging and pathology, making them one of the most common endocrine issues. Although most TNs are benign, about 5% to 15% can be malignant [3]. This highlights the need for precise evaluation to detect cancer early, allowing for timely treatment. Proper differentiation between benign and malignant nodules helps prevent the spread of thyroid cancer and avoids unnecessary surgeries in benign cases [4].

Distinguishing between benign and malignant thyroid nodules is crucial for proper treatment, as malignant nodules require timely intervention to prevent metastasis, while benign nodules need minimal intervention. Early diagnosis through tools like sonography and FNAC improves survival and avoids unnecessary surgeries, reducing healthcare costs. Sonography, being a non-invasive and accurate first-line imaging method, is ideal for repeated use and helps assess thyroid nodule characteristics such as shape, composition, echogenicity, and calcifications [5].

Ultrasound is a sensitive and commonly used tool for detecting thyroid nodules, often more effective than clinical palpation. However, its accuracy in distinguishing benign from malignant nodules is limited [6,7]. Performing a biopsy on every thyroid nodule is neither cost-effective nor ideal due to the stress it may cause patients. Therefore, clear guidelines are essential to identify which nodules genuinely need to be biopsied. Although fine-needle aspiration biopsy (FNAB) is the most reliable method for diagnosis, many patients are reluctant to undergo the procedure without a confirmed suspicion of cancer. To address this, classification systems like TI-RADS (introduced by Horvath in 2009) help assess cancer risk based on suspicious ultrasound features [8]. Given that the malignancy rate in thyroid nodules ranges from 4.0% to 6.5%, ultrasound-based risk stratification helps target high-risk nodules for biopsy and avoid unnecessary procedures for low-risk ones [9]. Accurate identification of key sonographic features is crucial for improving diagnostic accuracy. Therefore, this study aims to characterize thyroid nodules using ultrasonography to better guide decisions regarding FNAC.

This cross-sectional observational study was conducted in the Department of Radio-Diagnosis at F.H. Medical College, Agra, over a period of 18 months. A total of 138 patients with thyroid nodules were included in the study. Inclusion criteria were patients with nodules ≥1 cm, those undergoing ultrasound imaging for classification, and those who provided written informed consent. Patients with diffuse thyroid enlargement were excluded.

The study commenced after obtaining approval from the institutional ethical committee and written informed consent from all participants. Demographic and clinical data were recorded. All patients underwent thyroid ultrasonography using high-frequency (5–15 MHz) transducers on Voluson S8, Voluson S10, and LOGIQ Expert S7 machines. Nodules >10 mm with normal or elevated TSH levels were further evaluated with ultrasound-guided fine-needle aspiration.

Table 1: Distribution of thyroid nodules according to age in the study group

The study included 138 patients with thyroid nodules. Most were aged 31–40 years (26.81%), followed by 18–30 years (24.64%) and 41–50 years (21.01%). Fewer cases were seen in the 51–60 years (14.49%) and >60 years (13.04%) groups. The mean age was 40.12 ± 7.36 years.

Regarding sex distribution, females accounted for 67.39%, while males comprised 32.61%, indicating a higher prevalence in females.

Table 2: Distribution according to number of nodules and thyroid nodules according to ACR TIRADS scoring system.

Among the 138 patients, multiple thyroid nodules were more common, observed in 78.26% (108 cases), while solitary nodules were seen in 21.74% (30 cases). Based on the ACR TIRADS scoring system, the majority of nodules were classified as TIRADS 3 (32.6%), followed by TIRADS 2 (28.9%) and TIRADS 4 (18.1%). Fewer nodules were categorized as TIRADS 1 (14.4%) and TIRADS 5 (5.7%), indicating most nodules were of low to intermediate suspicion.

Figure 1: graphical representation of the distribution of thyroid nodules according to cytopathological diagnosis.

The cytopathology diagnosis of the 138 thyroid nodules revealed that 75.3% were benign, 13% were indeterminate, and 11.5% were malignant. This distribution highlights the predominance of benign cases in the study.

Table 3: Distribution of thyroid nodule according to shape of nodule and thyroid nodule according to margin.

Among the 138 thyroid nodules analyzed, the majority had a wider-than-tall shape (92.1%), while taller-than-wide nodules accounted for only 7.9%. Taller-than-wide nodules were more frequently associated with malignancy (5.7%) and showed a significant association (Chi-square = 43.86, p < 0.0001).

Regarding nodule margins, most had a smooth margin (73.9%), followed by ill-defined (12.3%), irregular (10.1%), and extra-thyroidal extension (3%). Malignancy was more commonly observed in nodules with extra-thyroidal extension and irregular margins, with the association being statistically significant (Chi-square = 47.05, p < 0.0001).

Table 4: Distribution of Thyroid Nodules According to Echogenicity, Composition, and Calcification.

The calcification type showed a significant difference across nodule types. Absent calcification was most common, found in 68.8% of cases, with the majority in benign nodules (53.6%). Large comet tail artifacts appeared in 13.7% of cases, while rim calcification and microcalcification were less common. Chi-square = 46.19, p < 0.0001 indicated statistical significance in the distribution.

Regarding composition, the majority of nodules were solid (40.5%), followed by mixed solid-cystic (29.7%) and cystic (18.1%) nodules. Malignancy was more frequent in solid nodules (9.4% for both Indeterminate and Malignant), with a significant result (Chi-square = 26.42, p < 0.001).

For echogenicity, the majority of cases were hyperechoic or isoechoic (48.5%), followed by anechoic (20.2%) and hypoechoic (23.9%). Markedly hypoechoic nodules were more likely to be malignant. The Chi-square = 27.76, p = 0.0001 suggests a significant relationship between echogenicity and nodule type.

Table 5: Malignancy rates in ACR TI-RADS

Sonography using the ACR TIRADS system revealed that as the TIRADS category increased, the risk of malignancy also rose. In TIRADS 1 and TIRADS 2, no malignant cases were found, with a 0% malignancy risk. In TIRADS 3, 2.1% were malignant, resulting in a 6.6% risk. For TIRADS 4, 4.3% were malignant, with a 24.0% risk. In TIRADS 5, 5.0% were malignant, indicating an 87.5% malignancy risk. These findings demonstrate that higher TIRADS categories are associated with a higher likelihood of malignancy.

Table 6: Diagnostic accuracy of ACR TI-RADS (excluding indeterminate cases)

The ACR TIRADS system showed the highest overall accuracy at 85.83%, with good sensitivity (81.25%) and specificity (86.54%). Shape had the highest specificity (98.08%) and overall accuracy (91.67%), though its sensitivity was lower at 50%. Echogenic Foci demonstrated the highest NPV (94.06%) and high overall accuracy (87.50%). Margin had the lowest sensitivity (26.69%) but maintained relatively high specificity (90.28%). Composition and Echogenicity showed moderate performance, with composition yielding an overall accuracy of 72.50% and echogenicity achieving 77.50%

In this study, participants ranged from 18 to over 60 years, with a mean age of 40.12 ± 7.36 years. The highest prevalence of thyroid nodules was seen in the 31–40 age group (26.81%), followed by 18–30 years (24.64%), with lower prevalence in those over 60 years (13.04%). A clear female predominance was observed (67.39%), consistent with the known gender distribution in thyroid disorders.

Multiple nodules were more common (78.26%) than solitary nodules (21.74%), though solitary nodules were found to be more suspicious for malignancy. According to ACR TIRADS, most nodules were categorized as TR3 (32.6%) and TR2 (28.9%), with only 5.7% falling under TR5, indicating a predominance of benign lesions. The malignancy risk correlated with increasing TIRADS scores—ranging from 0% in TR1–2 to 87.5% in TR5. ACR TIRADS demonstrated high diagnostic performance with a sensitivity of 81.25%, specificity of 86.54%, and negative predictive value (NPV) of 96.77%.

Among specific sonographic features, the taller-than-wide shape had the highest specificity (98.08%) and a positive predictive value (PPV) of 80%, while margin irregularity showed low sensitivity (26.69%). Of the nodules evaluated, 75.3% were benign, 13% indeterminate, and 11.5% malignant, lower than the 32% malignancy rate reported by Youssef et al. [10] Malignant nodules were significantly associated with sonographic features such as irregular margins, hypoechogenicity, solid composition, microcalcifications, taller-than-wide shape, and extrathyroidal extension (p < 0.0001). These findings are consistent with Papapostolou et al.[11], who underscored the diagnostic value of taller-than-wide shapes and microcalcifications.

Penaka H et al. [12] reported that, among 50 solitary thyroid nodules, ultrasonography correctly identified 33 benign and 17 malignant cases, with a sensitivity of 85.7% and specificity of 80%. Similarly, Xie C et al. [13] stated that ultrasonography is a safe, rapid, and effective tool for evaluating thyroid nodules.

Most nodules with smooth margins (73.9%) turned out to be benign, while those with irregular or ill-defined edges were more often seen in malignant or indeterminate cases. The extrathyroidal extension was found only in malignant nodules, making it a strong red flag for cancer. Calcifications were seen in about a third of the nodules—especially microcalcifications, which were closely linked to papillary thyroid carcinoma. Solid nodules had the highest chance of being cancerous, whereas cystic ones were always benign. Hypoechoic nodules were more likely to be malignant, emphasizing the importance of echogenicity and composition in identifying high-risk cases.

Overall, the findings underscore the importance of sonographic features and ACR TIRADS classification in differentiating benign from malignant thyroid nodules. Given the relatively low malignancy rate (11.5%), ultrasonography remains a critical, non-invasive tool in the initial evaluation, guiding the selection of nodules for further cytological assessment. Sonographic features such as irregular margins, microcalcifications, solid composition, taller-than-wide shape, and hypoechogenicity are valuable predictors that, along with TIRADS, enhance risk stratification and inform FNAC decisions.

Sonography plays a crucial role in the characterization of thyroid nodules by providing valuable information that aids in assessing the risk of malignancy. Key sonographic features, such as nodule shape, margin, echogenicity, and composition, have significant associations with malignancy. The ACR TIRADS scoring system proves to be an effective tool for categorizing nodules based on their risk level, with higher TIRADS categories correlating with a higher likelihood of malignancy. Overall, sonography serves as an essential non-invasive diagnostic tool in guiding clinical decisions, such as the need for fine-needle aspiration (FNA) and subsequent therapeutic management.

Limitations:

• Ultrasound has limitations, such as operator dependency and indeterminate results.
• A combined approach with clinical, cytological, and histopathological evaluations is essential for accurate diagnosis.
• Larger, multicenter studies with standardized imaging criteria are recommended to improve ultrasound's diagnostic value in thyroid nodule assessment.

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