Combining strain elastography with conventional ultrasound to improve the diagnostic evaluation of thyroid nodules
Date of Award
Master of Medicine (MMed)
Prof Sudhir Vinayak
Dr Ravjit Sagoo
Imaging and Diagnostic Radiology (East Africa)
Background and justification: Thyroid nodules are very common in the general population with autopsy data showing a prevalence of up to 65%. Of these, however, less than 10% of the nodules are cancerous hence an effective and accurate method of differentiating benign from malignant nodules is vital for adequate management of patients with thyroid nodules and therefore reducing unnecessary FNAC (fine needle aspiration cytology).
Objective: The aim of this study was to evaluate the diagnostic performance of combining elastography with conventional ultrasound in the differentiating the characteristics of thyroid nodules, using FNAC as a standard gold reference.
Methods: This was a prospective cross-sectional study carried out in the Aga Khan University Hospital, Nairobi included all adult patients with thyroid lesions that required ultrasound guided FNAC. Prior to the FNAC, the patients had a sonoelastogram and were graded according to the Rago criteria by a consultant radiologist with experience in elastography. These results were correlated with the FNAC results. Data were entered into the SPSS software v25.0. The outcome variable generated was dichotomous (benign or suspicious). Observational remarks on frequency of suspicious nodules were made. The sensitivity and specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy were calculated for conventional sonography and ultrasound with elastography methods. The McNemar test was applied to compare the two methods. All estimates were presented with appropriate 95% CIs. A P < 0.05 was considered statistically significant.
Results: Of the 66 nodules, 12 were suspicious and 54 were benign. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of grey scale ultrasound (GSU) for the 49 nodules were 50%, 66%, 24%, 87% and 53% respectively. Although the sensitivity of the combination of grey scale ultrasound and elastography was higher than grey scale ultrasound alone, this was not significantly different furthermore the specificity, PPV and accuracy of grey scale ultrasound was higher than the combination with the specificity being significantly higher.
Conclusion: Elastography alone, as well as the combination of elastography and grey scale ultrasound, showed inferior performance in the differentiation of suspicious and benign thyroid nodules compared with grey scale ultrasound features; elastography was not a useful tool in recommending fine-needle aspiration cytology.
Shariff, F. R. (2020). Combining strain elastography with conventional ultrasound to improve the diagnostic evaluation of thyroid nodules (Unpublished master's dissertation). Aga Khan University, East Africa.