Preoperative staging of thyroid papillary carcinoma with ultrasonography
Introduction
Imaging studies are currently being applied to a wide spectrum of thyroid diseases: in the detection of lesions, differential diagnosis, staging of malignant tumor, and follow-up after thyroidectomy [1]. Modern high-resolution ultrasonography (US), as well as color Doppler and power Doppler flow imaging, have demonstrated high accuracy in differentiating benign from malignant lesions 2, 3, 4, 5.
On the other hand, the widespread use of fine-needle aspiration biopsy and cytologic analysis has reduced the importance of imaging studies for differentiating between benign and malignant lesions, such that US is now used mainly to identify an appropriate nodule for aspiration biopsy [6].
Therefore, in the management of thyroid malignancy, a key use of imaging studies should be the evaluation of local extension and metastasis, both for choosing an appropriate treatment and predicting disease prognosis [1]. Accordingly, this prospective study was designed to assess the usefulness of high-resolution US and Doppler flow imaging in the preoperative work-up for thyroid papillary carcinoma.
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Materials and methods
One hundred and seventy patients with thyroid papillary carcinoma underwent total thyroidectomy at the Department of Surgery II in our institution between January 1991 and December 1996. In 77 of these cases (11 male, 66 female; age 33–70 years), US examinations were carried out prior to fine needle aspiration biopsy. Tumor size in these 77 patients varied from 7 mm to 8 cm in greatest dimension (1 cm or less in seven cases, and greater than 4 cm in 16 cases). Multifocality was seen in 15
Results
T categories were accurately estimated with US in 63 of 77 (81.8%) cases, and they were underestimated in 13 of 35 T4 cases (Table 1). In 7 of 38 Ex0 cases and 6 of 16 Ex1 cases, invasion beyond the capsule was pathologically proved (Table 2). The sensitivity, specificity and accuracy rates in the evaluation of extra-capsular invasion with US were 62.9, 97.6 and 81.8%, respectively. Dependence of the sensitivity on the location of extra thyroidal invasion is summarized in Table 3. Except when
Discussion
Generally speaking, prognosis of patients with thyroid neoplasm is determined by histopathologic type, clinical stage, age, gender, etc. 8, 9, 10. The higher the clinical stage, the poorer the prognosis. US is a more sensitive technique than physical examination for determination of T and N categories [11]. For the staging of primary tumor, the presence of tumor extension beyond the thyroid capsule is highly significant [3]. Extrathyroidal extension into the soft tissues of the neck is found in
Conclusion
In conclusion, US was here shown to be useful for the preoperative investigation of thyroid papillary carcinomas, though several limitations still exist, particularly in evaluating extracapsular invasion to deep locations and lymph node metastasis.
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