Computed Tomography Scans Before Surgery for Thyroid Cancer

I n this issue of Thyroid, Park and colleagues (1) report a detailed study on the anatomical features of thyroid pyramidal lobes as visualized on computed tomography (CT). Although ultrasound remains the first line thyroid imaging modality in most regions of the world, CT scanning of the neck provides important anatomical information that can assist thyroid clinicians with critical decision-making.

There are two major indications for CT scanning of the thyroid gland. First, CT scanning is useful in determining the extent of large nodular goiters, especially if a substernal component is suspected. Secondly, in cases of invasive thyroid cancer in which local–regional invasion is suspected, CT scanning may assist the surgeon in assessing resectability and the need for adjacent organ resection. When a CT scan of the neck is obtained for other reasons, information about the thyroid gland is a standard part of the interpretation. However, the pyramidal lobe is often overlooked on thyroid imaging studies. Park's study provides important information on the frequency of pyramidal lobe visualization on CT scanning and outlines useful tips for assessing pyramidal lobe anatomy. Thyroid clinicians will undoubtedly find these data of interest.

[Editor's Note: In addition to being a primary site for the occurrence of thyroid cancer, the pyramidal lobe may be invaded by thyroid cancer from the isthmus. I recall one patient in whom pyramidal lobe involvement was the origin of persistently elevated serum thyroglobulin concentrations after total thyroidectomy. This may not be a common problem because the pyramidal lobe is not mentioned in the Revised American Thyroid Association Management (ATA) Guidelines for Patients with Thyroid Nodules and Differentiated Thyroid Cancer (2). The manuscript by Park et al. (1) on the prevalence and features of thyroid pyramidal lobes in this issue of Thyroid raises the question of whether pyramidal lobe involvement should be considered in the preoperative staging of thyroid cancer. Recommendation 21 of the ATA guidelines (2) states the “preoperative neck ultrasound (US) for the contralateral lobe and cervical (central and especially lateral neck compartments) lymph nodes is recommended for all patients undergoing thyroidectomy for malignant cytologic findings on biopsy. US-guided FNA or sonographically suspicious lymph nodes should be performed to confirm malignancy if this would change management.” This recommendation was given a B rating, the second highest rating based on the available evidence. In contrast, the recommendation that followed, stating that “routine preoperative use of other imaging studies (CT, MRI, PET) is not recommended” was given an E rating and did not highlight situations in which preoperative imaging with modalities such as CT would be useful. Accordingly, Dr. Inabnet was asked to contribute a brief commentary on this question. —C.H.E.]