Hepatic Gas: Widening Spectrum of Causes De-tected at CT and US in the Interventional Era

RadioGraphics 2011; 31:1403-1413

Priti A. Shah, MD , Steven C. Cunningham, MD , Tara A. Morgan, MD Barry D. Daly, MD

The spectrum of causes of hepatic gas detected at computed tomog­raphy (CT) and ultrasonography (US) is widening. There are many iatrogenic and noniatrogenic causes of hepatic parenchymal, biliary, he­patic venous, and portal venous gas. Hepatic gas may be an indicator of serious acute disease (infarct, infection, abscess, bowel inflammation, or trauma). In other clinical scenarios, it may be an expected finding related to therapeutic interventions (such as surgery; hepatic artery emboliza­tion for a tumor or for active bleeding in acute trauma cases; percutane­ous tumor ablation performed with radiofrequency, cryotherapy, laser photocoagulation, or ethanol). In some cases, hepatic gas is an inciden­tal finding of no clinical significance. Familiarity with the expanding list of newer intervention-related causes of hepatic gas detected at CT and US, knowledge of the patient's clinical history, and a careful search for associated clues on images are all factors that may allow the radiologist to better determine the clinical relevance of this finding.