10.20\ Thyroidectomy

10.20.1  Discussion

Thyroidectomy consists of surgical resection of part or all of the thyroid glands for treating benign and malignant conditions. The basic types of thyroidectomy are listed in Table 10.5 and depicted in Figs. 10.100, 10.101, 10.102, and 10.103.

The traditional approach for thyroidectomy involves making a transverse incision several centimeters above the sternal notch. The use of robots and extracervical approaches, such as the axillary approach, has made minimally invasive thyroid surgery possible.

Perioperative tracheal perforation, recurrent laryngeal nerve injury, hematoma, and infection are potential early complications of thyroidec-

Table 10.5  Basic types of thyroidectomy

tomy that can have correlate findings on diagnostic imaging (Figs. 10.104, 10.105, and 10.106). Furthermore, imaging plays an important role in the postoperative evaluation for thyroid cancer. Ultrasound is generally suitable for evaluating the region of the surgical bed region, whereby tumor typically appears as hypoechoic or cystic nodules that might contain microcalcifications, especially with papillary thyroid carcinoma (Fig. 10.107). However, CT, MRI, and in cases of dedifferentiated thyroid cancer 18FDG-PET/CT are more sensitive for identifying recurrent tumor that encroaches upon the trachea (Fig. 10.108), which is a relatively common site of recurrence due to the difficulty in completely resecting tumor in that area. Furthermore, these modalities are better suited for identifying retropharyngeal lymph node metastases (Fig. 10.109), which can

be predisposed by altered lymphatic drainage following neck dissection.

Iodine 131 total body scans play an important role in the treatment and evaluation of local and distant tumor burden in patients with differentiated thyroid cancer after surgery has been performed (Fig. 10.110). High doses of I-131 are administered to ablate any residual thyroid tissue after thyroidectomy, since it is usually not ­feasible to remove all thyroid tissues during thyroidectomy. Activity in the region of the thyroid bed on the

initial postsurgical scans is common. In particular, a thyroglossal duct remnant is apparent on postoperative I-131 scintigraphy in about one-third of patients after total thyroidectomy and appears as a midline linear band of increased activity superior to the thyroid bed. This finding should not be confused with metastases, since the presence of metastatic disease warrants even higher treatment doses. The expected end point after successful therapy is the absence of activity in the thyroid bed and other locations besides the salivary glands.

Fig. 10.101  Hemithyroidectomy. Axial CT image shows a residual left thyroid lobe containing cysts (arrow) and surgical clips in the right thyroidectomy bed

Fig. 10.103  Total thyroidectomy. Axial CT image shows complete absence of the thyroid gland as well as the left strap muscles. The remaining right strap muscles (arrow) should not be confused for tumor

Fig. 10.102  Near-total thyroidectomy. Axial CT image shows a small amount of residual posterior thyroid tissue adjacent to the tracheoesophageal grooves, right greater than left (arrows)

Fig. 10.104  Thyroidectomy complicated by tracheal perforation. Axial CT images show extensive anterior neck emphysema after recent thyroidectomy and a defect in the anterior wall of the trachea (arrow)

Fig. 10.105  Vocal cord paralysis. Axial CT image at the level of the thyroid bed (a) shows left hemithyroidectomy bed that extends into the left tracheoesophageal groove along the expected course of the recurrent laryngeal nerve.

Fig. 10.106  Abscess. Axial CT image shows a fluid collection in the anterior neck (*) extending from the thyroid bed. Secondary signs of infection, including skin thickening, subcutaneous fat stranding, and reactive lymph nodes are also apparent

Fig. 10.108  Recurrent papillary thyroid carcinoma. Axial CT image shows an infiltrative mass in the left thyroidectomy bed and tracheoesophageal groove (arrow), with invasion of the tracheal lumen

Axial CT image at the level of the vocal cords (b) shows ipsilateral left vocal cord atrophy secondary to left recurrent laryngeal nerve injury

Fig. 10.107  Recurrent tumor in thyroidectomy bed. Ultrasound image shows a hypoechoic mass with microcalcifications in the thyroidectomy bed in a patient with a history of papillary thyroid carcinoma

10.21\ Neck Exploration

and Parathyroidectomy

10.21.1  Discussion

Parathyroidectomy for parathyroid adenomas or hyperplasia is typically performed either as unilateral or bilateral neck exploration at the level of the thyroid gland. Normal portions of parathyroid gland that are encountered during exploration of a parathyroid adenoma can be reimplanted in the forearm, sternocleidomastoid, or subcutaneous tissues of the neck, such that function is maintained (Fig. 10.111). Parathyroid adenoma recurrence and adenomas in ectopic parathyroid glands are the main causes of failed neck exploration (Figs. 10.112 and 10.113). It is also important to be aware that adenomas can also arise in glands that have been surgically repositioned (Fig. 10.114). Options for imaging prior to re-­ exploration include technetium (99mTc) sestamibi scanning, ultrasound, and four-dimensional (4D) CT, or a combination of these. It has been reported that the sensitivity of 4D CT for localization is 88% compared with 54% for sestamibi imaging.

Fig. 10.109  Postoperative retropharyngeal lymph node metastasis. The patient has a history of papillary thyroid carcinoma, status post thyroidectomy and neck dissection. Axial fat-suppressed T2-weighted MRI shows an abnormal right retropharyngeal lymph node (arrow)

Fig. 10.111  Parathyroidectomy with parathyroid gland autotransplantation. Sagittal CT image shows a parathyroid gland (arrow) implanted in the midline subcutaneous tissues of the lower anterior neck

Fig. 10.113  Failed neck exploration due to ectopic parathyroid. The patient’s hypercalcemia and related symptoms persisted following bilateral neck exploration. Coronal CT image shows a vertically elongated enhancing lesion along the carotid sheath superior to the thyroid gland (arrow). The initial surgical exploration was performed inferior and to the right of the lesion, as demarcated by the surgical clips

Fig.10.112  Residual hyperplastic parathyroid. Axial CT image shows an avidly enhancing nodule (arrow) in the left neck adjacent to surgical clips

Fig. 10.114  Adenoma in a parathyroid gland previously surgically transplanted along the sternocleidomastoid muscle. Axial CT image shows a heterogeneous tumor along superficial aspect of the right sternocleidomastoid (arrow)