感染性主動脈瘤是一少見但致死率高的疾病，因此早期診斷且給予適當的治療是很重要的。本篇報告一罕見病例:核磁共振掃描無法肯定診斷，我們利用鎵-67-檸檬酸鈉造影偵測出感染性胸主動脈瘤。

Gallium-67 (67Ga) citrate has been used for detecting infection and inflammation ever since its discovery in 1971. At the sites of inflammation， it is taken by leukocytes and bacterial siderophores. It has an affinity to lactoferrin which is released from degranulated neutrophils. To our knowledge， mycotic aneurym detected by 67Ga scan has rarely been reported. We report an interesting case of infected aneurysm of thoracic aorta detected by 67Ga citrate scan but was indeterminate on the MRI study.