Ultrasonography in the evaluation of cold thyroid nodules.

In our catchment area of roughly 1 million inhabitants(tertiary referral centre) a diagnosis of thyroid malig-nancy is made in 20 patients each year. Only about 50%of these patients have a solitary cold thyroid nodulerevealed on scintiscan. The total number of patientsevaluated for a solitary thyroid nodule is 200 each yearand because usually only 10 of these patients proves tohave thyroid malignancy, it is generally believed that therisk of thyroid malignancy in a solitary nodule referredfor diagnostic examination is approximately 2–5%.However, correctly performed epidemiological studies tosubstantiate this have not been undertaken.As diagnosing the few malignant lesions has oftenbeen compared to ‘looking for a needle in a haystack’,thyroid surgery has been the treatment of choice inmost patients in a number of centres (including ours) fora number of years. This has mainly been based onscepticism as to the reliability of fine-needle biopsy as adiagnostic criterion and, considering that the majorityof patients have few or no complaints, has led tosuperfluous surgery in the vast majority of patients. It istherefore in the interest of both patients and society, notleast for economic reasons, to achieve better selection ofcandidates for surgery.It has generally been believed that diagnostic imagingcould assist this aim, and imaging of the thyroid(anterior neck) has increasingly been used in the pri-mary evaluation of the thyroid nodule. For a number ofreasons ultrasonography (US) has evolved as the imag-ing modality most often used in most centres. In additionto its low cost, rapid investigation, the aquisition ofdynamic pictures, the possibility of performing guidedbiopsies and punctures, its non-ionizing nature andeasy accessibility, the technique allows determination ofthyroid and nodule size, echo structure (diffuse, uni- ormultinodular), echogenicity (iso-, hyper- or hypoechoicstructures) and evaluation of adjoining neck structures.Indeed, a number of centres use US-guided biopsy as theinitial step in the evaluation of the thyroid nodule,although this remains a matter of debate (1, 2).Fujimoto