摘要目的:建立基于 18F-FDG PET/MR诊断初诊甲状腺乳头状癌(PTC)淋巴结转移(LNM)的标准并评价其诊断效率。 方法:回顾性分析2021年5月至2023年8月于空军军医大学第一附属医院术前2周先后行 18F-FDG PET/MR和超声检查的14例PTC患者[均为女性，年龄(38.8±13.5)岁]资料。对所有患者进行逐级(Ⅱ～Ⅵ区)和逐颈(左侧、右侧和中央区)的视觉和半定量评估，在MRI-T 2加权成像(WI)上测量所有可疑淋巴结的尺寸，PET上测量SUV max。以术后病理作为参考标准，采用多因素logistic回归分析确定预测LNM的独立危险因素，通过ROC曲线分析评价各个模型的诊断效能。 结果:手术共清扫21个淋巴结宏观区域(恶性15个、良性6个)，178个淋巴结(恶性120个、良性58个)。多因素logistic回归分析显示，SUV max[比值比( OR)＝1.865，95% CI：1.323～2.630， P<0.001]和MRI短径(SD-MRI)( OR＝1.752，95% CI：1.189～2.580， P＝0.005)是预测LNM的独立危险因素。SD-MRI预测LNM的界值为5.7mm[AUC＝0.812，约登指数(YI)＝0.463]，当SD-MRI界值≥5.7或<5.7mm时，对应的SUV max界值分别为1.6和1.8。"双阈值"(SD-MRI≥5.7mm且SUV max≥1.6或SD-MRI<5.7mm且SUV max≥1.8)作为 18F-FDG PET/MR诊断标准，AUC和YI可提高至0.909和0.818。基于区域分析，超声、MRI与 18F-FDG PET/MR"双阈值"标准评估LNM的灵敏度、特异性和准确性分别为11/15与12/15与13/15、5/6与3/6与5/6、76.2%(16/21)与71.4%(15/21)与85.7%(18/21)。 结论:与超声和MRI相比， 18F-FDG PET/MR"双阈值"标准在诊断PTC患者LNM清扫范围方面较为准确，灵敏度较高。

abstractsObjective:To establish criteria for diagnosing lymph node metastasis (LNM) in newly diagnosed papillary thyroid cancer (PTC) patients based on 18F-FDG PET/MR and evaluate its diagnostic efficiency. Methods:The data of 14 patients with PTC (all females, age (38.8±13.5) years) who underwent 18F-FDG PET/MR and ultrasound sequentially 2 weeks before surgery at the First Affiliated Hospital of the Air Force Medical University from May 2021 to August 2023 were retrospectively analyzed. Visual and semi-quantitative assessments were performed on all patients step by step (Ⅱ-Ⅵ area) and neck by neck (left, right, and central area). The dimensions of all suspected lymph nodes were measured on T 2 weighted imaging (WI)-MRI and SUV max was measured on PET. Taking postoperative pathology as the reference standard, the independent risk factors for predicting LNM were determined by multivariate logistic regression analysis, and the diagnostic efficiency of each model was evaluated by ROC curve analysis. Results:A total of 21 macroscopic regions of lymph nodes(15 were malignant, 6 were benign) and 178 lymph nodes (120 were malignant, 58 were benign) were cleared by surgery. Multivariate logistic regression analysis showed that SUV max (odds ratio ( OR)=1.865, 95% CI: 1.323-2.630, P<0.001) and short diameter on MRI (SD-MRI) ( OR=1.752, 95% CI: 1.189-2.580, P=0.005) were independent predictors of LNM. The cut-off value of SD-MRI in predicting LNM was 5.7mm (AUC=0.812, Youden index (YI)=0.463). For the SD-MRI cut-off values ≥5.7 or <5.7mm, the corresponding SUV max cut-off values were 1.6 and 1.8, respectively. When " dual threshold" quantitative criteria (SD-MRI≥5.7mm + SUV max≥1.6 or SD-MRI<5.7mm + SUV max≥1.8) was used as the diagnostic criteria of 18F-FDG PET/MR, the AUC and YI could be improved to 0.909 and 0.818. Based on the regional level analysis, sensitivity, specificity, and accuracy of LNM diagnosis by ultrasound, MRI, and 18F-FDG PET/MR " dual threshold" criteria were 11/15 vs 12/15 vs 13/15, 5/6 vs 3/6 vs 5/6, 76.2%(16/21) vs 71.4%(15/21) vs 85.7%(18/21), respectively. Conclusion:Compared with the ultrasound and MRI, the 18F-FDG PET/MR " dual threshold" criteria exhibits higher sensitivity and accuracy in determining the scope of LNM clearance for PTC patients.