Ultrasound in Recurrent Thyroid Disease

Postablative 131I SPECT/CT Is Much More Sensitive Than Cervical Ultrasonography for the Detection of Thyroid Remnants in Patients After Total Thyroidectomy for Differentiated Thyroid Cancer

PURPOSE

Evaluation of utility of cervical ultrasound (US) for detection of thyroid remnants (ThR) in patients after thyroidectomy for differentiated thyroid cancer.

METHODS

Included were 154 consecutive patients (17-89 years, 123 female and 31 male patients), without known cancer residues or cervical lymph nodes metastases, admitted for ThR ablation with I, 14 to 20 weeks after surgery. Neck uptake of I (Tup) and thyroglobulin were determined, and location and volume of ThR detected by cervical US were recorded. On days 3 to 4 after ablation (1.7-4.6GBq, 46-124.3 mCi I), neck SPECT/CT was performed, and I uptake foci were assigned to one of the regions as described below. The anterior neck was divided into 2 compartments: superior and inferior to lower margin of thyroid cartilage, and each compartment was subdivided into middle and lateral regions (in SPECT/CT, posterolateral and anterolateral regions were also marked out). I uptake sites and ThR detected by US, if congruent with SPECT/CT, were counted and analyzed.

RESULTS

In total, 341 I uptake foci were found in 150 patients (97.4%) by SPECT/CT and 213 corresponding ThR in 118 patients (76.6%) by US. Ultrasound detected 30% to 46% of I uptake foci in superior lateral regions, 49% in pyramidal lobe/thyroglossal duct area (both P < 0.05), 74% to 77% in inferior lateral regions, and 22% in isthmus (both P > 0.05). Correlation between ThR volume and Tup was strong (r = 0.79), and that between ThR volume and thyroglobulin was weak (r = 0.24).

CONCLUSIONS

Ultrasound is less sensitive than I posttherapy scans for ThR detection in patients after thyroidectomy, especially for remnants located above the lower margin of thyroid cartilage.

ENDOCRINE TUMOURS: Imaging in the follow-up of differentiated thyroid cancer: current evidence and future perspectives for a risk-adapted approach

The clinical and epidemiological profiles of differentiated thyroid cancers (DTCs) have changed in the last three decades. Today's DTCs are more likely to be small, localized, asymptomatic papillary forms. Current practice is, though, moving toward more conservative approaches (e.g. lobectomy instead of total thyroidectomy, selective use of radioiodine). This evolution has been paralleled and partly driven by rapid technological advances in the field of diagnostic imaging. The challenge of contemporary DTCs follow-up is to tailor a risk-of-recurrence-based management, taking into account the dynamic nature of these risks, which evolve over time, spontaneously and in response to treatments. This review provides a closer look at the evolving evidence-based views on the use and utility of imaging technology in the post-treatment staging and the short- and long-term surveillance of patients with DTCs. The studies considered range from cervical US with Doppler flow analysis to an expanding palette of increasingly sophisticated second-line studies (cross-sectional, functional, combined-modality approaches), which can be used to detect disease that has spread beyond the neck and, in some cases, shed light on its probable outcome.

Post-thyroidectomy neck ultrasonography in patients with thyroid cancer and a review of the literature

The importance of routine neck ultrasonography for the detection of unsuspected local or nodal recurrence of thyroid cancer following thyroidectomy (with or without neck dissection) is well documented in many journal articles and international guidelines. Herein, we present a pictorial summary of the sonographic features of benign and malignant central neck compartment nodules and cervical lymph nodes via a series of high-quality ultrasonographic images, with a review of the literature.

Malignant thyroid bed mass after total thyroidectomy

Purpose

Ultrasonographic (US) criteria on malignant thyroid bed mass have been suggested, including taller than wide shape, loss of echogenic hilum, abnormal vascularity, and microcalcification. The relationship between fine-needle aspiration (FNA) cytology findings and US findings on thyroid bed mass is unknown. We have retrospectively assessed the malignant thyroid bed mass after total thyroidectomy due to papillary thyroid carcinoma (PTC).

Methods

We retrospectively evaluated 2,048 patients who underwent total thyroidectomy due to PTC. FNA was performed in 97 patients on the thyroid bed under US surveillance. The 97 suspicious thyroid bed masses were divided into two groups: metastatic thyroid bed group (n = 34) and nonmetastatic group (n = 63). The groups were evaluated according to various clinical, serologic, and US findings.

Results

Within a median 47.0 months of follow-up, the proportion of malignant thyroid bed mass was high in large tumor size (1.37 cm vs. 1.03 cm), isthmic position (10.3% vs. 3.9%), and previous N1a (55.9% vs. 34.9%). US findings revealed that the presence of microcalcification or macrocalcification (47.1% vs. 19.0%) and thyroid bed mass height (5.4 mm vs. 3.9 mm) were the only discriminable criteria for central compartment recurrence. But, degree of echogenicity, loss of hilum, and irregularity of margin failed to discriminate malignant thyroid bed mass.

Conclusion

US findings on malignant thyroid bed mass were different from previously reported general criteria on lateral metastatic nodes. Additional FNA cytology should be performed on patients, even low-risk patients, who present the above findings.

Ultrasonographically detected small thyroid bed nodules identified after total thyroidectomy for differentiated thyroid cancer seldom show clinically significant structural progression

BACKGROUND

High-resolution ultrasound (US) is the primary tool used to identify locoregional recurrences in differentiated thyroid cancer. Although small thyroid bed (TB) nodules are a commonly reported sonographic finding, their natural history, regardless of whether they are benign or malignant, has not been well characterized. This study was designed to determine the likelihood, magnitude, and rate of growth of small TB nodules identified on routine surveillance neck US after thyroidectomy for differentiated thyroid cancer as well as to identify ultrasonographic and clinical predictors of growth.

METHODS

This retrospective review identified 191 patients with at least one TB nodule (≤ 11 mm) on the first postoperative US performed at a comprehensive cancer center. Change in size of each TB nodule was determined using serial US studies over time. Clinicopathologic and sonographic characteristics were analyzed as possible predictors for growth of the TB nodules.

RESULTS

Over a median clinical follow-up of 5 years, 9% (17/191) of patients had increase in size of at least one TB nodule. Median size of the TB nodules was 5 mm (range: 2-11 mm). Suspicious US features were seen in 63% (121/191) of patients with TB nodules identified on initial US and in 31% (21/67) of those with TB nodules detected on subsequent follow-up US. The rate of growth was 1.3 mm/year in those nodules showing an increase in size and thus demonstrated a significant increase in size only after several years of follow-up. The negative predictive values associated with the absence of any suspicious US features (0.97), the absence of abnormal cervical lymph nodes (0.94), and the lack of a rising serum thyroglobulin (0.93) provided clinically useful information regarding the likelihood that nodules would not increase in size.

CONCLUSION

Most TB nodules do not show clinically significant growth over several years of follow-up. Thus, TB nodules can be followed up with cautious observation and serial ultrasonography using an approach similar to that recommended by the American Thyroid Association thyroid cancer guidelines for the management of small abnormal cervical lymph nodes.