What is the primary medical imaging technique used to assess thyroid nodules?

The primary medical imaging technique used to assess thyroid nodules is ultrasound. This technique is favored because it provides excellent visualization of the thyroid gland and its nodules. Ultrasound is non-invasive, does not involve ionizing radiation, and allows for real-time assessment of the nodules' size, characteristics (such as solid vs. cystic), and vascularity, which are important factors in guiding further management.

Additionally, ultrasound can be used to guide fine-needle aspiration (FNA) biopsies of thyroid nodules, which is a crucial step in evaluating whether a nodule is benign or malignant. Other imaging modalities, such as CT scans and MRIs, are generally not used as first-line investigations for thyroid nodules due to their higher cost, exposure to radiation, and lower specificity compared to ultrasound. X-rays are not helpful for evaluating thyroid nodules at all, as they cannot provide detailed images of soft tissue structures, such as the thyroid gland.