Department of Nuclear Medicine, Ankara Oncology Education and Research Hospital, Ankara, Turkey.
Clin Nucl Med. 2012 Oct;37(10):953-9. doi: 10.1097/RLU.0b013e31825b2057.
This study aimed (a) to determine the clinical and histopathologic factors that are related to FDG avidity in the recurrence/metastases of patients with differentiated thyroid carcinoma (DTC) who present with elevated thyroglobulin (Tg) levels and negative 131I whole-body scans (WBSs), (b) to clarify Tg cutoff levels in this setting, and (c) to evaluate the impact of PET/CT on patient management strategies and hence to critically look into the importance of PET/CT in combination with Tg in clinical decision making.
A total of 105 patients with DTC with negative 131I WBS and neck ultrasound but elevated Tg, who underwent FDG PET/CT for the suspicion of recurrent/metastatic disease, were included in this analysis. All patients had previously undergone total thyroidectomy and radioiodine ablation/therapy. PET/CT results were correlated with Tg levels and clinical and histopathologic characteristics of the primary tumor compared with the follow-up data.
PET/CT was true-positive in 69 patients (of which 23 had surgically amenable disease), true-negative in 20, false-positive in 6 patients and false-negative in 10 patients. Extrathyroidal spread was an independent risk factor related to FDG-avid recurrence. Tumor size was significantly higher in PET-positive patients than others, 2.25 (1.8) versus 1.5 (1.1) cm, P = 0.02. Significant correlation was observed between PET positivity and high Tg levels (P = 0.0001). Receiver operating characteristic curve analysis demonstrated a Tg cutoff of 1.9 ng/mL under thyroid-stimulating hormone suppression, 38.2 ng/mL with thyroid-stimulating hormone stimulation. Among PET-negative patients, no recurrence was detected in patients with undetectable/suppressible Tg in on-therapy state.
PET positivity correlated with extrathyroidal spread, and elevated Tg in recurrent/metastatic DTC. FDG PET/CT in combination with Tg levels was crucial in defining management strategies in patients with DTC with negative 131I WBS. A negative FDG PET/CT scan predicts a favorable prognosis and lack of recurrence on follow-up in patients with "suppressible Tg" levels in the on-therapy state despite significant elevation of Tg in the off-therapy state.
本研究旨在：(a)确定与甲状腺球蛋白 (Tg) 水平升高且 131I 全身扫描 (WBS) 阴性的分化型甲状腺癌 (DTC) 患者复发/转移时 FDG 摄取相关的临床和组织病理学因素；(b) 阐明该情况下的 Tg 截断值；(c) 评估 PET/CT 对患者管理策略的影响，从而批判性地探讨 PET/CT 结合 Tg 在临床决策中的重要性。
共纳入 105 例 DTC 患者，131I WBS 和颈部超声阴性但 Tg 升高，怀疑复发/转移行 FDG PET/CT。所有患者均行甲状腺全切除术和放射性碘消融/治疗。将 PET/CT 结果与 Tg 水平以及与原发肿瘤的临床和组织病理学特征进行比较，并与随访数据进行比较。
69 例患者 PET/CT 阳性（其中 23 例有手术可切除的疾病），20 例阴性，6 例假阳性，10 例假阴性。甲状腺外扩散是与 FDG 摄取阳性复发相关的独立危险因素。PET 阳性患者肿瘤直径明显大于阴性患者，分别为 2.25(1.8)cm 和 1.5(1.1)cm，P=0.02。PET 阳性与 Tg 水平显著相关(P=0.0001)。受试者工作特征曲线分析显示，TSH 抑制时 Tg 截断值为 1.9ng/mL，TSH 刺激时 Tg 截断值为 38.2ng/mL。在 PET 阴性患者中，治疗期间 Tg 水平不可测/可抑制的患者未发现复发。
DTC 复发/转移时，PET 阳性与甲状腺外扩散和 Tg 升高相关。FDG PET/CT 结合 Tg 水平对 131I WBS 阴性的 DTC 患者的管理策略具有重要意义。在治疗期间 Tg 水平升高但可抑制的患者中，FDG PET/CT 扫描阴性预测预后良好，且随访中无复发。
