Diagnostic accuracy of the combined use of conventional sonography and sonoelastography in differentiating benign and malignant solitary thyroid nodules

Abstract

Objective: To assess the diagnostic accuracy of combined use of conventional grayscale US and sono-elastography in differentiating benign and malignant solitary thyroid nodules.
Materials and methods: This prospective study included 50 patients with solitary thyroid nodules being evaluated using grayscale US followed with sono-elastography (USE). Suspicious conventional sonographic data for malignancy then evaluated using USE were classified according to Rago criteria with calculation of strain ratio. The diagnostic performances of grayscale US, elastography with Rago criteria, for predicting thyroid malignancy were compared and cutoff value for strain ration was statistically analyzed. Finally all patients with solitary nodule were subjected to US-guided FNAC and 35 patients recommended for surgery in the form of 12 patients underwent total thyroidectomy and 23 patients underwent thyroidectomy with neck dissection.
Results: 30 females (60%), and 20 males (40%) were included (Mean age 38) with final diagnosis comprised 29 (58%) pathologically proved benign thyroid nodules and 21 (42%) pathologically proved malignant nodules. US showed significant relation between markedly hypo-echogenicity, oval than tall, margin irregularity, presence of micro-calcification with diagnosis of thyroid malignancies with p value <0.001. Regarding sonoelastography, there was significant relation between elastography scores 4 and 5 and thyroid malignancies showing sensitivity of 80%, a specificity of 100%, and p value <0.001. The most accurate strain ratio cutoff value among studied cases was 2.52. Combination of grayscale US and sono-elastography yielded better results with sensitivity of 92%, specificity of 95%, PPV of 89%, NPV of 92% and diagnostic accuracy or efficacy of 96%.
Conclusion: Combined use of USE and grayscale US, showed superior performance in the differentiation of malignant and benign thyroid nodules compared with each technique alone. Suspicious US criteria with elasticity Rago scores 4 and 5 and strain ratio more than 2.52 are the most predictive signs of malignancy.