European Journal of Cardiovascular Medicine

The thyroid gland, an essential part of the endocrine system, is prone to various conditions such as congenital abnormalities, inflammatory disorders, and tumors, which often manifest as thyroid nodules.^1,2 These nodules can be either benign or malignant, making accurate diagnosis crucial for effective treatment. Ultrasonography is widely used as a primary imaging technique for evaluating thyroid nodules due to its non-invasive nature and accessibility. However, it is not definitive in distinguishing benign from malignant nodules.

Fine Needle Aspiration Cytology (FNAC) is commonly employed to differentiate between benign and malignant thyroid nodules. While FNAC is valuable diagnostically, it is an invasive procedure that carries risks, including pain and, in rare cases, severe hemorrhage from injury to nearby blood vessels. Moreover, determining which nodules require FNAC can be challenging.³

To mitigate these issues, the Thyroid Imaging Reporting and Data System (TIRADS) was introduced. TIRADS categorizes thyroid nodules based on ultrasound characteristics that are associated with malignancy, aiding in clinical decision-making and helping to determine when FNAC is necessary.^4,5 Present study was aimed to study High-Frequency Ultrasound (HFU) in evaluating thyroid nodules, emphasizing its potential to enhance diagnostic accuracy and its integration with TIRADS to improve clinical outcomes in thyroid disease management.

Present study was Observational Cross-Sectional study, conducted in department of Radio-diagnosis at Dr. V. M. Government medical college & hospital, Civil Chowk, Solapur, India. Study duration was of 18 months (June 2022 to February 2024). Study was approved by institutional ethical committee.

Inclusion criteria

• Patients of any age and gender with primary thyroid-related complaints, referred to the Radiology Department for Ultrasonography of the thyroid gland to evaluate thyroid nodules, willing to participate in present study

Exclusion criteria

• Patients with secondary thyroid disorders such as drug- or radiation-induced hypothyroidism or hyperthyroidism.
• Patients with secondary thyroid involvement due to central nervous system disorders.
• Patients unable to give consent (e.g., psychiatric patients).
• Pregnant women.
• Patients who refused to give consent.

Study was explained to participants in local language & written informed consent was taken. Patients referred to the Radiology Department for ultrasonography of the thyroid gland, specifically for the evaluation of thyroid nodules, were analyzed based on their primary thyroid complaints. This included a thorough review of relevant medical histories, both positive and negative, as well as a proper clinical examination of the thyroid gland. Patients were selected for the study based on an evaluation of their clinical details and by applying the following inclusion and exclusion criteria.

The selected patients underwent High frequency ultrasound was performed using 3-12 MHz linear probe of the thyroid gland to assess the presence and characteristics of thyroid nodules. Based on these ultrasound features, the thyroid nodules were stratified into the appropriate Thyroid Imaging Reporting and Data System (TIRADS) categories.  Following the ultrasound evaluation, patients, if necessary, underwent ultrasound- guided fine needle aspiration cytology (FNAC). In cases of multiple nodules, the nodule with the most suspicious sonographic findings for malignancy or the dominant nodule was selected for FNAC. The procedure and potential complications were explained to the patients, and informed consent was obtained.

The confirmatory diagnosis from the FNAC material was obtained from the Pathology Department. These FNAC results were then compared with the ultrasound findings (TIRADS categories) of the corresponding nodules. The correlation between the ultrasound findings and the histopathological reports from thyroid surgery specimens was analyzed, particularly in cases where the FNAC results were indeterminate or inadequate.

Data was collected and compiled using Microsoft Excel, analysed using SPSS 23.0 version.

The present study has been undertaken in 100 patients presented with primary thyroid related complaints. The patients were analyzed by ultrasonography and fine needle aspiration cytology. Ultrasonographically the thyroid nodules were evaluated for shape (wider than taller, taller than wider), echogenicity (isoechogeni city, hyperechogenic city, hypoechogenic city and marked hypoechogenic city), content of the nodules (solid, mixed), calcification (no calcification, microcalcification, macrocalcification) and margins (smooth, irregular, micro lobulated). The results are shown below.

Out of 100 nodules evaluated 97 nodules were wider than taller in shape and 3 nodules were taller than wider in shape. Among the 97 nodules which were wider than taller in shape 92 nodules showed benignity on FNAC report. The remaining 5 nodules were malignant in nature on FNAC. All the nodules which showed taller than wider in shape showed malignant character. According to the current study the nodules which had wider than taller shape has 94.1% chances of benignity and 5.1% chances of malignancy. The nodules which had taller than wider shape have 100% chances of malignancy.

Table 1: Number of thyroid nodules depending upon the Shape

Ultrasonographically 86 thyroid nodules showed either isoechogeni city or hyperechogenic city, 8 nodules showed hypoechogenic city and the remaining 6 nodules demonstrated marked hypoechogenic city. All the 86 nodules which had iso or hyperechogenic city on USG have demonstrated benignity on FNAC. Among the 8 nodules which had hypo echogenicity 6 nodules were benign and 2 were malignant on FNAC. All the nodules which showed marked hypoechogenic city were malignant. So, the nodules with iso or hyperechogenic city on USG are benign in 100% cases. The nodules with hypoechogenic city have 75% chances of benignity and 25% chances of malignancy. The nodules with marked hypoechogenic city have 100% chances of malignancy.

Table 2: Number of thyroid nodules depending upon Echogenicity

Ultrasonographically 51 nodules were solid in nature and 49 nodules demonstrated mixed content (solid and cystic). Out of 51 nodules which were solid in nature 43 nodules were benign and 8 nodules were malignant on FNAC. So the nodules which have solid content have 84.3% chances of benignity and 15.7% chances of malignancy and the nodules which have mixed content have 100% chances of benignity.

Table 3: Number of thyroid nodules depending upon Content

Out of the 100 nodules analyzed 88 nodules had no calcification 5 had macrocalcification and 7 had microcalcification. The nodules which had no calcification have 97.7% chances of benignity and 2.3% chances of malignancy The nodules which had macrocalcification have 100% probability of benignity The nodules which have microcalcification have 85.7% chances of malignancy and 14.3% chances of benignity

Table 4: Number of thyroid nodules depending upon Calcification

Among the 100 nodules 70 nodules had smooth margin, 26 nodules had irregular margin and 4 nodules had microlobulated margin on USG. The nodules which had smooth margin on USG have 98.6% chances of benignity and 1.4 chances of malignancy on FNAC. The nodules which had irregular margin have 88.5% chances of benignity and 11.5 % chances of malignancy. Out of 4 nodules which had microlobulated margin all was demonstrated malignant character on FNAC. So, the nodules which have microlobulated margin on USG have 100% chances of malignancy on FNAC.

Table 5: Number of thyroid nodules depending upon the Margin

According to the ultrasound features all the thyroid nodules were categorized into TIRADS category. Out of the 100 nodules evaluated 70 nodules were included in TIRADS category 3, 6 nodules in category 4a and 20 nodules in category 4b. The remaining 4 nodules were included under category 5. All the nodules in category 3 were shown benign character on histopathology. One nodule in category 4a and three nodules in category 4b were malignant and all the 4 nodules in category 5 had malignant character in histopathology.

Table 6: Number of thyroid nodules depending upon TIRADS category

TIRADS category 3 nodules present a 0% risk of malignancy, while TIRADS category 5 nodules have a 100% risk of malignancy, indicating an increasing risk from TIRADS category 3 to TIRADS category 5.

Table 7: Percentage of thyroid nodules depending upon TIRADS category

Ultrasonography is a widely used tool for evaluating thyroid nodules; however, reporting of thyroid ultrasounds can often be vague, subjective, and inconclusive. To address these issues, this study aimed to enhance the sensitivity and specificity of ultrasonography and to classify thyroid nodules into five major categories using the Thyroid Imaging Reporting and Data System (TIRADS) for diagnosing malignant nodules.

Thyroid gland malignancy has a prevalence of approximately 5%. Several studies have reported that less than 10% of thyroid nodules are malignant.^4,5 In the present study, 8% of thyroid nodules were found to be malignant based on histopathological examination, which is consistent with findings from previous research.

A study by Moifo B. et al.,⁶ indicated that the risk of malignancy increases progressively from TIRADS category 2 to category 5. In their study, the risk of malignancy was reported as 0% in TIRADS category 2. For TIRADS categories 3, 4a, and 4b, the risk of malignancy was 2.2%, 5.9%, and 57.9%, respectively. TIRADS category 5 was associated with a 100% risk of malignancy. In our current study, no thyroid nodules were classified as TIRADS category 2.

In this study, the risk of malignancy for TIRADS categories 3, 4a, and 4b was found to be 0%, 16.7%, and 15%, respectively, with TIRADS category 5 showing a 100% risk of malignancy. Horvath et al. suggested that the risk of malignancy for TIRADS categories 3, 4a, and 4b is typically less than 5%, 5–10%, and 10–80%, respectively, while TIRADS category 5 carries a risk of greater than 80%. The findings in the present study align with those reported by Horvath et al.,⁷ except for TIRADS category 4a, where we observed a slightly higher risk of malignancy. This discrepancy may be attributed to inter-observer variability in the assessment of thyroid nodule margins.

There are various ultrasound features associated with increased risk of thyroid malignancy. These features include taller-than-wider shape, irregular contour, marked hypoechogenic city and the presence of microcalcifications. Presence of these features is suspicious for malignancy.

Moifo et al.,⁶ reported that the presence of irregular contour of the thyroid nodules had the sensitivity, specificity of 34.78%, 99.51% respectively. In a study conducted by Kwak et al., the odds ratios for various sonographic features associated with an increased risk of malignancy were reported as follows: marked hypoechogenic city had an odds ratio of 69.756 (CI: 37.216–130.747), microlobulated margins had an odds ratio of 20.135 (CI: 14.038–28.880), irregular margins had an odds ratio of 113.828 (CI: 60.771–213.205), microcalcifications had an odds ratio of 25.871 (CI: 17.503–38.240), and a taller-than-wide shape had an odds ratio of 24.478 (CI: 17.152–34.933). This    study indicates that all of these sonographic features are significantly associated with an increased risk of thyroid malignancy.

In the present study, the taller-than-wider shape, marked hypoechogenic city, and microlobulated margins observed in ultrasonography were found to be 100% specific for malignancy. Several sonographic features are consistently associated with benign thyroid nodules. These include isoechogeni city or hyperechogenicity, mixed (solid and cystic) content, and the presence of macrocalcification. Such features are useful for excluding malignant thyroid nodules. However, rare exceptions, such as cystic necrosis in papillary carcinoma, were not observed in our study.

Sonographic features such as irregular margins, microlobulated margins, marked hypoechogenic city, microcalcification, and a taller-than-wide shape are all associated with an increased risk of malignancy. Notably, microlobulated margins, marked hypoechogenic city, and a taller-than-wide shape are 100% specific for malignancy. Conversely, features such as isoechogenicity or hyperechogenic city, mixed (solid and cystic) content, and macrocalcification are indicative of benign nodules.^8,9,10,11

Nodules classified as TIRADS category 3 or lower do not require FNAC; instead, they should be monitored with a short-term follow-up every 6 months to ensure stability, given the slow growth rate of thyroid malignancies.^12,13,14 A follow-up period of at least 2 years is recommended. Only nodules categorized as TIRADS 4 and 5 should undergo biopsy to differentiate between benign and malignant cases.

High-Frequency Ultrasound is a reliable method for assessing the morphology of thyroid nodules. Using a standardized lexicon and categorizing findings according to TIRADS offers several benefits:

1. It ensures objectivity in reporting.
2. It improves the accuracy of identifying malignant lesions.
3. It aids in clinical decision-making.
4. It helps avoid unnecessary FNAC procedures.
5. It reduces patient discomfort, minimizes costs, and conserves resources.

Conflict of Interest: None to declare

Source of funding: Nil

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