Enhanced Scintigraphic Visualization of Thyroglossal Duct Remnant during Hypothyroidism after Total Thyroidectomy: Prevalence and Clinical Implication in Patients with Differentiated Thyroid Cancer

Abstract

TGDR can be frequently observed in scintigraphy of hypothyroid subjects after a thyroidectomy, even when clinically unexpected. Therefore, care should be taken not to confuse the tracer uptake by TGDR with metastatic foci in I- and Tc-scans of patients with hypothyroidism after a thyroidectomy for DTC.

The prevalence of thyroglossal tract thyroid tissue on SPECT/CT following 131I ablation therapy after total thyroidectomy for thyroid cancer

“…This hypothesis is supported by the results of Lee et al . who found that thyroglossal tract thyroid tissue can be occult on Tc‐99m pertechnetate planar scintigraphy performed in a euthyroid state preoperatively but subsequently become detectable under TSH stimulation following total thyroidectomy . In that study, thyroglossal tract thyroid tissue was found in 33·6% of patients following total thyroidectomy when withdrawn from thyroid hormone.…”

“…Thyroid tissue can be found anywhere along the embryological path of thyroid descent . The pyramidal lobe can be thought of as the most caudal part of the thyroglossal tract and has been reported to be present in approximately 25–61% of the normal population . The incidence of ectopic thyroid tissue is significantly lower, although in one autopsy study 10% of subjects had small amounts of thyroid tissue in the lingual muscle .…”

“…The pyramidal lobe can be thought of as the most caudal remnant of this thyroglossal tract but thyroid tissue may also be found more superiorly forming sites of ectopic thyroid tissue . During total thyroidectomy for thyroid cancer, the pyramidal lobe is typically excised to the level of the hyoid bone; however, some thyroglossal tract thyroid tissue may be separate from the thyroid gland, lie outside the operative field or even be occult at surgery . The prevalence and quantity of this residual thyroglossal tract thyroid tissue are poorly defined, and its presence may have implications in patients undergoing treatment with radioactive iodine (RAI).…”

Frequent visualization of thyroglossal duct remnant on post-ablation 131I-SPECT/CT and its clinical implications

“…19e23 The visualization of the pyramidal lobe during thyroid scanning of patients with Graves' disease can be explained by the same mechanism. 24 A study conducted by Lee et al 5 also supports the TSH-stimulation effect. They found that thyroid tissue in the thyroglossal tract can be occult on 99m Tc-pertechnetate planar scintigraphy performed in a euthyroid state preoperatively but becomes visible under TSH stimulation after total thyroidectomy.…”

Iodine Uptake Patterns on Post-ablation Whole Body Scans are Related to Elevated Serum Thyroglobulin Levels After Radioactive Iodine Therapy in Patients with Papillary Thyroid Carcinoma

“…Taken together, positive midline uptake on RxWBS could suggest a large amount of remnant thyroid tissues, such as TGDR [20,21], and post-ablation serum Tg might be affected by midline uptake regarded as TGDR. However, remnant burden alone is not sufficient to explain serum Tg elevation in patients with midline uptake.…”