Diagnostic Accuracy of Thyroid Imaging, Reporting and Data System Combined with Strain Elastography in the Evaluation of Thyroid Nodules

Abstract

Introduction:It is estimated that the prevalence of thyroid nodules is about 3-8% and there are always chances of malignancy in thyroid nodule which should not be underestimated. Fine Needle Aspiration Cytology (FNAC) is an efficient tool for diagnosing thyroid malignancies. Strain elastography measures the stiffness of nodules using ultrasound and serves as an additional diagnostic tool in differentiating benign and malignant thyroid nodules depending on their hardness. Aim: To characterise thyroid nodules based on Thyroid Imaging Reporting And Data System (TIRADS) combined with strain elastography in differentiating benign from malignant thyroid nodules and correlating them with FNAC/Histopathological Examination (HPE). Materials and Methods: A prospective cross-sectional study was conducted in which total of 135 patients were included who were diagnosed to have thyroid nodules by B-mode ultrasound or by palpation. For the evaluation of the strain ratio, the average strain value was obtained from 4 continuous frames of strain images and ratio of less than 2.50 was benign and more than 2.50 was considered malignant. Combined TIRADS and strain elastography scores were obtained and the results were correlated with histological findings by performing an FNAC/Biopsy. All statistical analysis were performed using Statistical Package for Social Science (SPSS, version 17) for Microsoft windows. The data were expressed as Mean and Standard Deviation (SD). Chisquare test were used for qualitative data. Results: Among the 135 thyroid nodules, Ultrasonography (USG) TIRADS scoring system differentiated benign and malignant nodules with sensitivity of 83%, while the specificity was 96.4%, Positive Predictive Value (PPV)=83.3%, Negative Predictive Value (NPV)=96.4% and accuracy of 94.1%. Strain elastography differentiated benign from malignant nodules with of sensitivity was 91.7%, while the specificity was 99.0%, PPV=95.7%, NPV=95.7% and accuracy of 98% while the combined TIRADS and strain elastography score differentiated benign from malignant nodules with sensitivity of 95.83%, while the specificity was 100%, PPV=100%, NPV=99.1% and accuracy of 99.3%. Conclusion: Grey scale ultrasound is an efficient tool for diagnosis of thyroid nodules. Elastography can further help in characterising thyroid nodules and can help in identifying sites for FNAC. Combination of both B-mode Ultrasound findings and strain elastography yield a better diagnosis.

Keywords

• fine needle aspiration cytology
• grey scale ultrasound
• thyroid malignancies