目的： 探讨甲状腺乳头状癌（papillary thyroid cancer， PTC）伴肺转移行甲状腺全切术，并行¹³¹I治疗清除手术后残留的甲状腺组织（简称清甲）后伴随肺转移的患者，在¹³¹I清除手术不能切除的远处或近处的转移癌灶（简称清灶）治疗后，全身扫描（post-therapy whole body scan，Rx-WBS）图像上的肝脏弥漫性¹³¹I摄取（diffuse hepatic uptake，DHU）水平对肿瘤转移负荷评估的辅助价值。方法： 回顾性纳入2020年6月至2025年2月上海交通大学医学院附属瑞金医院核医学科收治的22例PTC伴肺转移，拟进行¹³¹I清灶治疗的患者。患者同时满足如下3个条件，①实行甲状腺全切术；②完成¹³¹I清甲治疗；③¹³¹I清甲治疗期间全身扫描或胸部CT发现肺部多发结节，且刺激性甲状腺球蛋白（stimulated thyroglobulin，sTg）>10 ng/mL。采用双变量相关及多重线性回归模型分析Rx-WBS中肝脏¹³¹I摄取靶本比（target-to-background ratios，TBR_liver）、肺转移¹³¹I摄取靶本比（TBR_lung）与sTg、甲状腺球蛋白抗体（thyroglobulin antibody，TgAb）及¹³¹I治疗剂量等临床参数间的相关性。结果： TBR_liver与TBR_lung显著正相关（r=0.510，P<0.05），TBR_liver与sTg水平（r=0.218，P=0.331）及治疗剂量（r=0.334，P=0.128）不相关。多重线性回归分析显示，TBR_lung是TBR_liver独立影响因素（β=0.511，95%CI为0.053~0.453，P<0.05）。结论： PTC术后肺转移完成清甲的患者TBR_liver与肺转移灶¹³¹I摄取的功能状态有良好的相关性。尤其是当¹³¹I扫描肺结节阴性时，较高的TBR_liver有助于提示存在肺转移灶。

Objective To investigate the auxiliary value of diffuse hepatic ¹³¹I uptake (DHU) levels on post-therapy whole-body scan (Rx-WBS) images in assessing metastatic tumor burden in patients with papillary thyroid cancer (PTC) accompanied by lung metastases who underwent total thyroidectomy followed by radioiodine remnant ablation (RRA) and subsequently received ¹³¹I therapy for non-resectable distant or regional metastases. Methods A total of 22 PTC patients with lung metastases scheduled for ¹³¹I metastatic ablation therapy were retrospectively enrolled from the Department of Nuclear Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, between June 2020 and February 2025. The patients met the following three criteria: (1) total thyroidectomy; (2) completion of ¹³¹I RRA; (3) multiple pulmonary nodules detected on ¹³¹I RRA-period whole-body scan or chest CT, with stimulated thyroglobulin (sTg) >10 ng/mL. Bivariate correlation and multiple linear regression models were used to analyze the correlations of target-to-background ratios (TBR) of liver (TBR_liver) and lung metastases (TBR_lung) for ¹³¹I uptake with clinical parameters including sTg, thyroglobulin antibody (TgAb), and administered ¹³¹I dose. Results TBR_liver showed a significant positive correlation with TBR_lung (r=0.510, P<0.05). No significant correlations were found between TBR_liver and sTg (r=0.218, P=0.331) or administered dose (r=0.334, P=0.128). Multiple linear regression analysis identified TBR_lung as an independent influencing factor of TBR_liver (β=0.511, 95% CI: 0.053-0.453, P<0.05). Conclusion In PTC patients with lung metastases after thyroidectomy and RRA, TBR_liver demonstrates a significant correlation with the functional status of ¹³¹I uptake in lung metastases. Particularly when ¹³¹I scanning shows negative pulmonary nodules, elevated TBR_liver may serve as an indicator of the presence of lung metastases.