Ultrasound bests elastography for specificity of thyroid cancer diagnosis

Key clinical point: Ultrasound is more specific than elastography in helping clinicians make a presurgical diagnosis of thyroid cancer.

Major finding: Compared with elastography, ultrasound was more specific in presurgical diagnosis and in differentiating between benign and malignant thyroid nodules (specificity of 92% vs. 80%, respectively).

Data source: A pooled analysis of 14 prospective studies involving findings from 2,732 thyroid nodules.

Disclosures: Dr. Bhatia reported having no financial disclosures.




CORONADO, CALIF.– Compared with elastography, ultrasound predictors of malignancy were more specific for presurgical diagnosis and in differentiating between benign and malignant thyroid nodules, results from a pooled analysis showed.

“Elastography is controversial,” Dr. Parisha Bhatia said in an interview during the annual meeting of the American Thyroid Association. “Some studies have reported that it has better sensitivity and specificity, compared with conventional ultrasound, but others have found it not to be helpful.”

Dr. Parisha Bhatia

Dr. Parisha Bhatia

In an effort to compare the efficacy of elastography and ultrasound in determining benign and malignant thyroid nodules, and to determine if elastography has a complementary role to fine needle aspiration (FNA), Dr. Bhatia and her associates searched Embase and PubMed databases for articles involving more than 50 nodules using specimen histology as the reference standard. They discovered 14 prospective studies and organized them into one of two groups. Group 1 included nodules with FNA cytology–proven “benign/malignant” result. Group 2 included nodules with FNA cytology as “intermediate.” The elasticity score was compared with ultrasound features such as taller than wide, irregular margins, internal vascularity, calcification, and absence of halo to determine validity measures and likelihood ratios.

Dr. Bhatia, an endocrine surgeon at Tulane University, New Orleans, reported on findings from 2,732 nodules in the pooled analysis. Of these, 64% were benign, 25% were malignant, and 11% were indeterminate.

In group 1, elastography showed a sensitivity of 75%, a specificity of 80%, a positive predictive value (PPV) of 61%, a negative predictive value (NPV) of 89%, and a likelihood ratio of 5.7, with a higher predictive value for nodules smaller than 1 cm in diameter (PPV of 79% and NPV of 83%). The strongest ultrasound-related predictor of malignancies was “taller than wide” (a specificity of 92%, a NPV of 51%, yet a sensitivity of only 24%), followed by irregular margins (a specificity of 91%, sensitivity of 48%, and a PPV of 64%). Combination of elastography and ultrasound had the highest sensitivity (96%) and NPV (96%), yet lower specificity (46%) and PPV (46%).

In group 2, elastography yielded a higher sensitivity (90%) and NPV (92%), while ultrasound features were highly specific, with the highest values for “taller than wide” shape (85%) in these thyroid nodules.

“Ultrasound predictors of malignancy prove to be more specific for presurgical diagnosis and differentiation of benign and malignant thyroid nodules,” the researchers wrote in their abstract. “When used as an adjunct, the higher sensitivity and NPV of combination of both the techniques can lead to better selection of candidates for FNA.”

Dr. Bhatia acknowledged certain limitations of the study, including the fact that the pooled data contained little information on indeterminate thyroid nodules. She reported having no financial disclosures.

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