Kim Bo Kyu, You Sung-Hye, Kim Byungjun
Department of Radiology, Anam Hospital, Korea University College of Medicine, #126-1, 5-Ka Anam-dong, Sungbuk ku, Seoul 136-705, Republic of Korea.
Diagnostics (Basel). 2025 Jan 31;15(3):344. doi: 10.3390/diagnostics15030344.
The cavernous sinus air sign, historically linked to trauma or venous sinus thrombosis, has recently been reported in association with retrograde venous air embolism, often without clinical significance. Despite this, its exact prevalence, etiology, and clinical relevance remain unclear. This study aims to systematically evaluate the incidence of the cavernous sinus air sign in patients undergoing CT angiography (CTA) and to assess its potential clinical implications. We retrospectively analyzed data from patients who underwent CTA between January 2021 and December 2021. The cavernous sinus air sign was defined radiologically as air-density foci within the cavernous sinus, with Hounsfield units lower than those of orbital fat. Key variables included clinical indications for CTA, evidence of venous reflux of contrast media, the laterality of contrast injection, and the presence of brachiocephalic vein stenosis. Comparative analyses were performed to identify factors associated with the occurrence of the cavernous sinus air sign. Among the 2,821 patients evaluated, the cavernous sinus air sign was identified in 35 cases (1.2%). Notably, none of these patients had a history of trauma or venous sinus thrombosis. Follow-up CT imaging was available for 27 of the 35 cases (77.1%), and in all instances, the cavernous sinus air sign resolved spontaneously. A statistically significant association was found between the cavernous sinus air sign and left-sided peripheral intravenous contrast injection, observed in 8.6% of affected patients compared to 1.5% in those without the sign ( = 0.001). Venous reflux into the internal jugular vein was also more frequent in patients with the air sign (34.3% vs. 14.1%, = 0.001). These findings suggest a mechanical component, likely related to retrograde air embolism, influenced by anatomical and procedural factors. The isolated presence of the cavernous sinus air sign, in the absence of relevant clinical conditions, is most likely a benign, incidental finding associated with retrograde air embolism.
海绵窦空气征，在历史上与创伤或静脉窦血栓形成有关，最近有报道称其与逆行性静脉空气栓塞有关，通常无临床意义。尽管如此，其确切的发生率、病因及临床相关性仍不明确。本研究旨在系统评估接受CT血管造影（CTA）患者中海绵窦空气征的发生率，并评估其潜在的临床意义。我们回顾性分析了2021年1月至2021年12月期间接受CTA检查的患者数据。海绵窦空气征在影像学上定义为海绵窦内的空气密度灶，其亨氏单位低于眶内脂肪。关键变量包括CTA的临床指征、造影剂静脉反流的证据、造影剂注射的侧别以及头臂静脉狭窄的存在情况。进行比较分析以确定与海绵窦空气征发生相关的因素。在评估的2821例患者中，35例（1.2%）发现有海绵窦空气征。值得注意的是，这些患者均无创伤或静脉窦血栓形成病史。35例中有27例（77.1%）可获得随访CT影像，所有病例中海绵窦空气征均自发消失。在海绵窦空气征与左侧外周静脉注射造影剂之间发现有统计学意义的关联，有该征象的患者中8.6%出现此情况，而无该征象的患者中为1.5%（P = 0.001）。有空气征的患者中静脉反流至颈内静脉的情况也更常见（34.3%对14.1%，P = 0.001）。这些发现提示存在一个机械因素，可能与逆行性空气栓塞有关，受解剖和操作因素影响。在无相关临床情况时，孤立出现的海绵窦空气征很可能是与逆行性空气栓塞相关的良性偶然发现。
