Ultrasound thyroid nodule measurements: the "gold standard" and its limitations in clinical decision making

To highlight the limitations associated with use of ultrasonography for the evaluation of thyroid nodule or gland volume for clinical decision making.

We review the equipment (scanners and probes) used for ultrasonography and the appropriate measurements for assessment of thyroid nodules. The limitations of ultrasound thyroid measurements are summarized, particularly in reference to repeated measurements over time.

Thyroid ultrasonography is the recognized "gold standard" for an accurate and reliable assessment of gland volume and thyroid nodules. Many endocrinologists refer patients for surgical treatment because of detection of growth of thyroid nodules. In daily practice, they often make this decision by comparing ultrasound thyroid measurements determined over time. Although reliable, evaluation of thyroid nodule volume by ultrasonography has technologic, biologic, and examination technique limitations. These are particularly important in routine clinical practice, where ultrasound measurements are performed in less standardized settings than in experimental trials.

In daily medical office applications, ultrasound measurements of thyroid nodules should be used with caution in decision making.