The discovery of a thyroid nodule over 1 cm should prompt measurement of the serum TSH [7]. In a patient with a high or normal TSH, the likelihood of identifying a hyperfunctioning nodule is very low. The great majority of nodules in such patients will be either cold or warm on scanning; further evaluation of the need for FNA will be based solely on the sonographic features. As such, in patients with a normal or high TSH, scintigraphy is unnecessary (see Fig. 3.1) [7]. Conversely, a patient with a low TSH and one or more nodules requires scintigraphy to determine if the nodule(s) is(are) toxic and may be observed, or if further interrogation by fine needle aspiration is required in the event of a warm or cold nodule [7]. Consideration to scintigraphy may also be given in a patient with a cytologic diagnosis of follicular neoplasm, particularly if the serum TSH is in the low-normal range [11]. Molecular testing of such indeterminate nodules has largely replaced this approach in clinical practice, however [12].

Most benign and nearly all malignant nodules concentrate radioiodine less avidly than the surrounding normal thyroid tissue. Approximately 5 % of thyroid cancers, however, will concentrate pertechnetate but not radioiodine [13]. Such nodules may appear warm or hot on pertechnetate scans [14]. Consequently, it is recommended that patients with functioning nodules on ^99mTc-pertechnetate scans should undergo confirmatory imaging with radioiodine to determine their functional status [15].

Ultrasonography is rapidly gaining popularity among non-radiologists for use in the clinical setting. In point of fact, use of ultrasonography at the bedside has become a mandatory component of training for some surgery residencies and all endocrinology fellowships. The high prevalence of thyroid nodules, particularly the nonpalpable variety, necessitates a simple stratification tool to distinguish the benign lesions from those requiring further evaluation. As such, ultrasonography has become an extension of the physical examination in the evaluation of the patient with a thyroid nodule. Indeed, a properly trained clinician can provide a similarly informative exam as that of a radiologist [16].

The benefits of an ultrasound performed by a non-radiologist are manifold. Long-recognized as a more powerful tool when simultaneously performed and interpreted by the same individual, US exams increasingly are being done instead by technologists with subsequent interpretation of the images by a radiologist. Subtle findings on US such as comet-tail signs or microcalcifications easily can be missed when only static images are reviewed. Real-time sonography, in contrast, reveals a wealth of information about the subtle morphologic characteristics of a lesion and the background thyroid parenchyma. Further, the ability to visualize a structure in multiple planes offers a unique radiologic opportunity to create a three-dimensional image, providing important details regarding geographic relationships with nearby anatomic structures. These clues can provide additional context regarding the risk of malignancy or benignity for any given nodule.

From the patient’s perspective, clinician-performed exams may be preferable; the endocrinologist or surgeon can provide immediate feedback to the patient regarding the exam findings, rather than waiting for the radiologist’s report. These results can then prompt an immediate action, such as an FNA or counseling regarding the need for surgery, in the case of a suspicious nodule or lymph node. In fact, a study of 223 patients referred to a multidisciplinary thyroid nodule clinic revealed that the use of ultrasonography in the clinic altered the management in 63 % of patients [6].

For patients with a diagnosis of thyroid cancer, performing the appropriate initial surgery is a critical determinant of outcome, to minimize the risk of residual disease [7]. Thyroid cancer has a high predilection for metastatic spread to the locoregional lymph nodes; macroscopic nodal disease may be seen in up to 50 % of patients [17–19]. Preoperative US of the neck for identification of suspicious cervical lymph nodes is strongly recommended for all patients undergoing thyroidectomy for a malignant or suspicious cytologic diagnosis [7]. An appropriate initial surgery reduces the morbidity associated with multiple operations, which are often required when the diagnosis of nodal metastases is made after the thyroidectomy [20]. Additionally, the identification of nodal metastases alters the staging and, ultimately, may result in a modification of the treatment strategy [19]. When performed by a radiologist, the presence (or absence) of nodal metastases often is not assessed on preoperative ultrasound, unless specifically requested by the ordering physician. Indeed, one study found that the preoperative US performed in a radiology center missed 88 and 93 % of patients with suspicious central and lateral lymph nodes requiring FNA compared to the findings of an US exam by a surgeon [21]. Moreover, the findings on clinician-performed exam changed the surgical approach in 45 % of patients compared to the initial assessment based on the radiologic diagnoses [21].

Although sonography is a relatively simple procedure to perform, there are a few essential components of the exam that should be reviewed. It is critical to place the patient in the supine position with the neck hyperextended. Such positioning allows structures in the inferior neck and superior mediastinum to be more readily visualized. Attempts to identify the inferior parathyroid glands, a substernal goiter, or mediastinal lymph nodes may be unsuccessful if this important detail is overlooked. Occasionally, it may be necessary to place a pillow or towel roll between the patient’s shoulders to achieve greater extension of the neck.

The optimal method for performance of the sonographic exam has not been defined; it is of utmost importance though to cover all areas of the neck. Additionally, the inspection should include both the transverse and longitudinal (sagittal) views. When evaluating a patient with a thyroid nodule, assessment of the lymph nodes, particularly in the lateral neck, provides important clues regarding the malignancy risk. Identification of a suspicious lymph node increases the likelihood of cancer and may warrant FNA of the node in lieu of the thyroid [7] (see Fig. 3.2 normal neck anatomy).

Ultrasonography is a highly sensitive tool for the identification of thyroid nodules; screening for such lesions identifies nodules in up to 40 % of patients [22], with increasing incidence with advanced age [1]. The high prevalence of nodules and the relative infrequency of malignancy mandate a method of stratification, as there are insufficient resources to perform an FNA of every thyroid lesion identified. Various individual sonographic features have a high specificity for identification of malignancy [23]; the absence of one of these features, however, does not rule out the possibility of a cancerous nodule.