Czepczyński Rafał, Stangierski Adam, Oleksa Robert, Janicka-Jedyńska Małgorzata, Czarnywojtek Agata, Ruchała Marek, Sowiński Jerzy
Department of Endocrinology and Metabolism, Poznan University of Medical Sciences, Poznan, Poland.
Nucl Med Rev Cent East Eur. 2011;14(2):68-72. doi: 10.5603/nmr.2011.00018.
The value of PET/CT imaging in diagnosis of different cancers has been widely described. PET/CT may contribute to visualization of additional findings that were not the indication to the study and did not refer to initial diagnosis. In a small number of PET/CT scans an incidentally found focal ¹⁸F-FDG uptake in the thyroid gland is found. The goal of the study was to estimate the prevalence and evaluate the clinical significance of incidental thyroid ¹⁸F-FDG uptake in a cohort of patients diagnosed for different malignancies.
2478 PET/CT scans using ¹⁸F-FDG were performed in 1925 subjects for evaluation of different, non-thyroid malignancies. For PET/CT examination, a Discovery ST (General Electric) PET/CT scanner was used. Patients with focal ¹⁸F-FDG activity were further evaluated by means of fine needle aspiration biopsy (FNAB). If cytological examination disclosed malignancy or suspicion of malignancy, thyroidectomy was performed. Both cytological and histopathological results were then analyzed.
Focal increased ¹⁸F-FDG uptake was found in 71 patients (3.7%), and cytological or histopathological results were evaluable in 20 of them. In general, 8 cases of thyroid cancer were found, which accounts for 40% probability of malignancy. The predominant histopathological diagnosis was papillary thyroid carcinoma (5 out of 8 cases). Additionally, in one case (5%) thyroid metastasis of lung cancer was detected. Diffused ¹⁸F-FDG activity in both thyroid lobes was observed in 120 subjects (6.2%)--in most cases chronic thyroiditis was confirmed.
The probability of malignancy of focal thyroid incidentalomas in ¹⁸F-FDG PET/CT scans is rather high. Therefore, thorough evaluation of such lesions is highly recommended in each case. Most thyroid malignancies incidentally detected in PET/CT are papillary carcinomas.
PET/CT成像在不同癌症诊断中的价值已得到广泛描述。PET/CT可能有助于发现一些额外的病变，这些病变并非该检查的适应证，也与初始诊断无关。在少数PET/CT扫描中，会偶然发现甲状腺内有局灶性¹⁸F-FDG摄取。本研究的目的是估计在一组被诊断为不同恶性肿瘤的患者中，甲状腺偶然出现¹⁸F-FDG摄取的发生率，并评估其临床意义。
对1925名受试者进行了2478次使用¹⁸F-FDG的PET/CT扫描，以评估不同的非甲状腺恶性肿瘤。PET/CT检查使用Discovery ST（通用电气）PET/CT扫描仪。对有局灶性¹⁸F-FDG活性的患者进一步采用细针穿刺活检（FNAB）进行评估。如果细胞学检查发现恶性肿瘤或疑似恶性肿瘤，则进行甲状腺切除术。然后对细胞学和组织病理学结果进行分析。
71例患者（3.7%）发现局灶性¹⁸F-FDG摄取增加，其中20例患者的细胞学或组织病理学结果可评估。总体而言，发现8例甲状腺癌，恶性概率为40%。主要的组织病理学诊断为乳头状甲状腺癌（8例中的5例）。此外，1例（5%）检测到肺癌甲状腺转移。120名受试者（6.2%）双侧甲状腺叶出现弥漫性¹⁸F-FDG活性，大多数病例确诊为慢性甲状腺炎。
¹⁸F-FDG PET/CT扫描中甲状腺偶然发现的局灶性病变恶性概率相当高。因此，强烈建议对每例此类病变进行全面评估。PET/CT偶然发现的大多数甲状腺恶性肿瘤为乳头状癌。
