Introduction: Incidence of malignancy is higher among solitary nodules of thyroid than multinodular disease. There are not many studies quantifying the statistical measures of performance of test criteria of presence of individual gray scale features favouring malignancy in solitary nodules. This study attempts to quantify them and to derive policies to recruit solitary nodules for FNAC.

Aim of the work: (1) To estimate the statistical measures of the performance of each of gray scale ultrasound features as a test criterion to identify malignancy in solitary thyroid nodules.  (2) To see if a combination of ultrasound features which when present simultaneously will be more ‘positively predictive’/ ‘specific’ than individual features.

Patients and Methods: 40 cases of sonologically confirmed solitary nodules were selected from cases referred as ‘solitary nodule’ after palpation. The statistical measures of the performance of each of gray scale ultrasound features namely hypoechogenicity of a non-cystic nodule, microcalcifications, irregular margin and anteroposterior diameter equal to or more than transverse diameter, as a test criterion to identify malignancy in solitary nodules were calculated.

Results: When considered in isolation, each of the gray scale ultrasound features suggestive of malignancy has relatively low sensitivity in the setting of sonologically confirmed solitary nodules, though each of them has high specificity. The test criterion of presence of any one of the gray scale ultrasound features has a sensitivity of 100%.

Conclusions: All the solitary nodules with any one positive gray scale ultrasound feature should undergo FNAC. Simultaneous presence of any two or moresonologic features gives high levels of specificity and PPV; nodules should be considered highly suspicious.

Keywords: Solitary thyroid nodule, recruitment for FNAC, A/T ratio

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N.J. John

Associate Professor, Dept. of Radiodiagnosis, Govt. Medical College Hospital,

Medical College PO, Trivandrum, Kerala  Pin 695011 

Ph: 9447553678