Abstract
ObjectivesThe aim of the current study was to evaluate the value of preoperative 18F-FDG (FDG) PET/CT in predicting cervical lymph node (LN) metastasis in patients with papillary thyroid carcinoma (PTC).MethodsOne hundred and ninety-three newly diagnosed PTC patients (M: F = 25:168, age = 46.8 ± 12.2) who had undergone pretreatment FDG PET/CT and had neck node dissection were included in this study. The FDG avidity of the primary tumor and the SUVmax of the primary tumor (pSUVmax) were analyzed for prediction of LN metastasis. Detectability by ultrasonography (US) and FDG PET/CT for cervical LN metastasis were also assessed and compared with the pSUVmax.ResultsThe FDG avidity of the primary tumor was identified in 118 patients (FDG avid group: 61.0%, M: F = 16:102, age 47.0 ± 12.7 years) and pSUVmax ranged from 1.3 to 35.6 (median 4.6) in the FDG avid group. The tumor size in the FDG avid group was bigger and there was a higher incidence of LN metastasis compared to the FDG non-avid group (0.93 vs. 0.59 cm, p <0.001 and 49.2 vs. 33.3%, p <0.05). In the FDG avid group, patients with LN metastasis had higher pSUVmax than patients without LN metastasis (8.7 ± 8.3 vs. 5.7 ± 5.1, p <0.001). The incidence of central LN metastasis in patients with a pSUVmax >4.6 was 54%; however, the detectability of central LN metastasis by US and FDG PET/CT were 10.3% and 3.6%, respectively.ConclusionA high FDG avidity of the primary tumor was related to LN metastasis in PTC patients. Therefore, patients with a high pSUVmax should be cautiously assessed for LN metastasis and might need a more comprehensive surgical approach.
Highlights
Papillary thyroid carcinoma (PTC) is an endocrine neoplasm with a high incidence of lymphatic metastasis
A high FDG avidity of the primary tumor was related to lymph node (LN) metastasis in PTC patients
Pathologic tumor size was 0.8 ± 0.5 cm, microcarcinoma was seen in 78.2% (n = 151) of the patients and 43.0% (n = 83) had LN metastasis
Summary
Papillary thyroid carcinoma (PTC) is an endocrine neoplasm with a high incidence of lymphatic metastasis. The incidence of cervical lymph node (LN) metastasis in patients with well-differentiated thyroid carcinoma has been reported to be 20–90% [1]. Some large studies even reported reduced survival because of cervical LN metastases in PTC patients [4, 5]. Since determining the presence of cervical LN metastasis may suggest a different operation method, it is clinically important. Current guidelines recommend removal of all clinically involved metastatic LNs in the central and lateral compartments, which are visualized by preoperative radiological investigations using, for example, ultrasonography (US), enhanced computed tomography (CT), and magnetic resonance imaging (MRI) [6]. Preoperative CT, MRI, cervical US and 18F-fluoro-2-deoxy-D-glucose-positron emission tomography–computerized tomography (FDG PET/CT) has a low sensitivity (30–40%) for detecting cervical LN metastasis [7]
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