摘要目的:探讨 18F-脱氧葡糖(FDG)PET/CT双时相显像(DTPI)在探测主动脉移植物感染(AGI)中的诊断价值。 方法:前瞻性纳入2014年10月至2021年10月临床初诊为可疑AGI并行PET/CT DTPI患者42例，男35例，女7例，年龄(54±15)岁(22~79岁)。PET/CT图像质量分5级。对AGI诊断效能的评估采用半定量分析，记录病灶早期显像最大标准化摄取值(SUVmax)、延迟显像SUVmax和DTPI保留指数(RI，早期和延迟显像SUVmax变化的百分比)。以主动脉移植物感染管理协作组织(MAGIC)的AGI确诊依据为参考标准判断DTPI对AGI的诊断效能。结果:27例(64%，27/42)患者确诊为AGI。AGI组RI值高于非AGI组[(26.7 ±18.9)%对(6.4 ±18.8)%， P<0.01]。以SUVmax≥6为最佳阈值，常规早期PET/CT显像对AGI诊断的敏感度、特异性和准确性分别为88.9%、73.3%和83.3%。而DTPI延迟显像提高了对AGI诊断的敏感度(96.3%)和准确性(88.1%)。以DTPI RI ≥15%为最佳阈值提高了对AGI诊断的特异性(93.3%)和准确性(90.5%)。此外，AGI组56%(15/27)的患者均通过DTPI延迟显像提高了图像质量分级，从而可以更精确评价移植物感染灶的范围和程度。 结论:18F-FDG PET/CT DTPI较常规单次早期PET/CT显像改善PET图像质量，提高对AGI的诊断效能，更加精准评估AGI病灶的范围和程度，指导进一步治疗方案的制订。

abstractsObjective:To explore the diagnostic value of 18F-deoxyglucose (FDG) PET/CT dual-time-point imaging (DTPI) in the diagnosis of aortic grafts infection (AGI). Methods:Forty-two patients with suspected AGI were prospectively recruited in this DTPI study from October 2014 to October 2021. There were 35(83%) males and 7 females, mean age (54±15) years old, range 22-79 years old. PET/CT image quality was scored as 5 grading scale. Semi-quantitative analysis of DTPI data was performed using maximum standardized uptake value (SUVmax) of suspected AGI lesions. The percentage of SUVmax change between initial and delayed images were recorded as retention index (RI). Management of Aortic Graft Infection Collaboration (MAGIC) criteria were used as the diagnostic reference criteria for AGI.Results:According to the MAGIC criteria, 27 patients (64%) were positive for AGI, and 15 patients (36%) were negative. The mean RI of AGI was higher than that of non-AGI ones[(26.7±18.9)% vs. (6.4 ±18.8)%, P<0.01]. The sensitivity, specificity, and accuracy of initial SUVmax ≥6 with the presence of AGI was 88.9%, 73.3%, and 83.3%, respectively. Delayed SUVmax ≥6 improved the sensitivity (96.3%) and accuracy (88.1%) for diagnosing AGI. DTPI with 15% increment as the optimal cut-off value of RI improved the specificity (93.3%) and accuracy (90.5%) for diagnosing AGI. Fifteen (56%, 15/27) AGI patients had improved image quality grading on the delayed images, leading to more accurately delineating the detailed extent of the infected aortic graft. Conclusion:18F-FDG PET/CT DTPI has better diagnostic performance for AGI than conventional Single-time-point PET/CT imaging by improving image quality as well as enhancing delineation of infected aortic graft extent.