Diagnostic accuracy of sonoelastography in detecting malignant thyroid nodules: a systematic review and meta-analysis

Objective: The aim of this systematic review was to determine the diagnostic accuracy of sonoelastography in detecting malignant thyroid nodules.

Materials and methods: A systematic search in MEDLINE and bibliographic databases was performed for the terms "thyroid nodule" and "sonoelastography." The inclusion criteria were the report of a 4- or 5-point scoring scale for elasticity score by qualitative sonoelastography as the index test and fine-needle aspiration (FNA) cytology or histopathology for thyroid nodules as the reference standard. Studies in which only the strain ratio was reported and studies of patients with underlying medical conditions were excluded. The methodologic quality of the studies was assessed using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS) tool. A meta-analysis of diagnostic accuracy measures for sonoelastography was performed using Meta-DiSc freeware software (version 1.4).

Results: A total of 12 studies assessing 1180 thyroid nodules (817 benign and 363 malignant) were included. The most commonly used threshold for characterizing malignancy--that is, elasticity scores between 2 and 3--showed a sensitivity of 86.0% (95% CI, 81.9-89.4%) and specificity of 66.7% (95% CI, 63.4-69.9%) with positive and negative likelihood ratios and a diagnostic odds ratio of 3.82 (95% CI, 2.38-6.13), 0.16 (95% CI, 0.08-0.32), and 27.51 (95% CI, 9.21-82.18), respectively. The highest sensitivity of the test was achieved by a threshold elasticity score of between 1 and 2 with a sensitivity of 98.3% (95% CI, 96.2-99.5%).

Conclusion: Sonoelastography can be considered as a reliable screening tool for characterizing thyroid nodules. An elasticity score of 1 is indicative of benign pathology in almost all cases and can be used to exclude many patients from further invasive assessments.