For a right-handed individual who performs ultrasound, the traditional setup entails the ultrasound unit being to the left of the exam table (Fig. 4.4), with the patient supine on the table. This allows the sonographer (henceforth this term will apply to any physician or radiology technician performing the ultrasound exam) to face both the patient and the monitor. The goals of positioning are to expose the neck to allow movement of the transducer probe to all relevant anatomic areas and to ensure that the patient remains comfortable during the process, protecting those who may have spine issues or arthritis (Fig. 4.5a, b). Typically, the position entails gentle hyperextension of the neck with a soft pillow for support beneath the shoulders. The sonographer can ask the patient to bend their knees for comfort and protection of the lower back. It is helpful to ask the patient periodically if they remain comfortable and to remind them to indicate if this is not the case.

For patients who need lymph node mapping in the setting of known or suspected thyroid cancer, positioning needs to provide wide exposure of the lateral neck from the hairline and the angle of the mandible to the clavicles, with the chin averted to the contralateral side (Fig. 4.5c).

It is important to realize that a good ultrasound exam can be achieved despite positional challenges. For example, patients in a wheelchair can remain so and be supported when they simply stretch their neck backward. A patient sitting or standing even may have adequate neck exposure to capture the needed ultrasound image, especially if they have a long, thin neck (Fig. 4.5d).

The simple acronym “PPP ” has remained a guiding cue to the authors since first receiving this instruction in 1994: patient, probe, and preset. These three topics represent, in order, the safest method to start an ultrasound exam. First, the patient information needs to be entered accurately to ensure that the subsequent imaging is linked properly for interpretation, documentation, and storage. Next, the probe is selected based on the type of imaging planned. This is most relevant when ultrasound machines have several different probes connected. To detect if the desired probe is actually selected and engaged for display on the monitor, the sonographer can quickly note the shape of the footprint on the monitor (linear or curved) and as quickly touch one end of the footprint on the transducer to see if motion appears on the monitor. Finally, the preset refers to the exam-specific programming for optimal image resolution with emphasis on small parts or vascular features or even on thyroid-focused features at a specific depth. This may change between exams if different users have access to the ultrasound, thus it is valuable to make sure that the desired display setting is selected prior to the start of each new patient exam.

The proper orientation of the transducer probe is that when placed transversely on the front of the patient’s neck, the anatomy touching the left of the probe is displayed on the left of the monitor. By convention, the probe is rotated 90° clockwise so that in longitudinal (sagittal) placement, the cephalad anatomy touches the left of the probe and remains displayed on the left of the monitor (“head on left, feet on right”). It is tempting to look at the various notchings, dots, or other markings that are etched on the transducer probe to determine if the orientation is correct. Please avoid this tactic. Manufacturers make different markings and none correlate to uniform orientation. Furthermore, the ultrasound console has a keyboard function that allows the image on the monitor to be flipped. The easiest, most reliable way to orient the probe correctly is to place ultrasound gel on the footprint and touch one end of the probe to see where it moves on the display; similarly, it is easiest then simply to turn the probe in the hand to change orientations.

The ultrasound exam is best performed by the strategy of “do it the same way every time all the time.” The precise sequence may vary among specialists and sonographers. The main point is to form a consistent habit of the procedure that will maximize performing a complete exam and reduce omission of information needed for assessment and diagnosis. Protocols are available from respected professional associations: American Institute of Ultrasound in Medicine, AIUM [6] and Thyroid Cancer Care Collaborative, TCCC [7]. An example of a checklist protocol provided by the West Coast Ultrasound Institute (Phoenix, AZ) to sonography students during training is itemized in Table 4.1.

Highlighted here is a suggested sequence for a comprehensive endocrine neck ultrasound exam. Place the probe transversely on the anterior of the neck at the level of the isthmus, and scan superiorly until the hyoid bone (to detect the presence of a thyroglossal duct cyst in rare instances) and inferiorly into the upper mediastinum (Fig. 4.6). Note the visible portions of the thyroid lobes, the larynx/vocal cords, and the central neck and upper mediastinal lymph nodes (level 6 and 7; see schematic in Fig. 4.7). Move the probe to the center on the right thyroid lobe, and scan transversely to demonstrate the entire span of the right lobe from the upper pole to the lower pole, noting any abnormal findings. Rotate the probe 90° clockwise to acquire longitudinal images from the medial aspect adjacent to the trachea to the lateral edge adjacent to the carotid artery (Fig. 4.8). Repeat these same image acquisitions for the left thyroid lobe. Return to measure the thickness of the isthmus and three dimensions of the right and left lobes (anterior-posterior depth (D) × transverse width (W) × longitudinal length (L)). Volume if needed can be calculated for each lobe by the formula D × W × L × (π/6) which can be easily remembered as D × W × L × ½. Note and describe the abnormal thyroid pathology, and measure dominant nodules in the same three-dimensional convention. Categorize thyroid nodules in terms of the American Thyroid Association (ATA) risk of malignancy features [2]. Begin to form a diagnostic impression based on ATA pattern recognition strategies (thyroiditis, multinodular goiter, diffuse goiter, solitary nodule, thyroid cancer). Note the location of any abnormal parathyroid glands, and measure their size (normal parathyroid glands are not visible by ultrasound, but their expected distribution is depicted in Fig. 4.9). Note the presence of abnormal central neck lymph nodes, their features (reactive from thyroiditis versus abnormal from cancer metastases), and size. Apply the color Doppler analysis to assess overall thyroid gland vascularity and the vascular patterns specific to any discrete nodules. Scan the lateral neck briefly through levels 2–5 to detect any grossly evident lymphadenopathy. In real time, return to examine any area of the thyroid or the central and lateral neck that needs a more thoughtful or detailed evaluation.