J Surg Ultrasound.  2020 Nov;7(2):15-20. 10.46268/jsu.2020.7.2.15.

Relationship between Capsule Invasion and Ultrasound Imaging in Thyroid Cancer

• Kang SK
• Kim BK
• Sun WY
• Lee J

• KMID: 2511916
• DOI: http://doi.org/10.46268/jsu.2020.7.2.15

Abstract

Purpose
The main aim of this study was to determine if preoperative ultrasonography (US) of thyroid cancer can predict a pathologic invasion over the thyroid capsule and be used as an indicator in deciding the range of thyroidectomy.
Methods
A retrospective analysis was conducted on 408 patients who underwent a total thyroidectomy due to thyroid cancer. Among 408 patients, 254 patients showed pathologic capsular invasion, and 154 did not. The patients were categorized into three groups according to the relationship between the tumor and thyroid capsule shown in preoperative US. The clinical, sonographic, and pathologic data from each group were analyzed.
Results
The accuracy of preoperative US to predict pathologic capsular invasion by measuring the relationship between the thyroid capsule and cancer mass showed a sensitivity of 0.71, specificity of 0.55, and positive predictive value (PPV) of 0.72. On the other hand, the negative predictive value (NPV) was 0.53. Patients with pathologic capsule invasion showed a significant difference in cancer mass size and total harvested lymph nodes postoperatively compared to those without a capsule invasion. Multivariate analysis to determine the factors affecting the relapse of thyroid cancer after surgery, including clinical, sonography, and pathologic features, showed no significant difference except for female gender.
Conclusion
A preoperative US examination on its own is not enough to determine pathologic capsular invasion.

Keyword

Thyroid cancer; Ultrasonography; Thyroidectomy

Figure

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  Fig. 1 Categorization of ultrasound results with relationship between tumor and thyroid capsule. (A) Group 1: Capsular abutment; which is no tissue between capsule and tumor (B) Group 2: Capsular protrusion; it means loss of perithyroidal echogenic rim between capsule and thyroid tumor (C) Group 3: Tumor is well contained inside thyroid capsule without any abutment or protrusion with capsule.

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  Fig. 2 Categorization of patients using results of pathologic and ultrasound capsule invasion.

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