Hepatic artery aneurysms are rare; they have a high rate of spontaneous rupture and hemorrhage leading to mortality. The increase in the incidence of hepatic artery aneurysms may be attributed to the frequent use of imaging tests.
Most patients with hepatic artery aneurysms are asymptomatic and the aneurysm is discovered as an incidental finding on imaging being performed to work up unrelated symptoms or conditions. Patients with a hepatic artery aneurysm may present with abdominal pain, particularly epigastric discomfort, right upper quadrant pain, obstructive jaundice, and/or hemobilia [1] [2] [3]. In rare instances, a patient with a giant aneurysm may present with a pulsatile mass in the right upper abdomen. Patients often become clinically symptomatic when there is erosion into the biliary tree or the portal vein resulting in the development of portal hypertension or rupture of an aneurysm into the peritoneal or retroperitoneal cavity. Approximately one-third of patients present with hemobilia, characterized by jaundice, gastrointestinal bleeding, and biliary colic (Quincke's triad) [4]. Discovery of a hepatic artery aneurysm in an asymptomatic individual occurs as an incidental finding on a computed tomography or ultrasound exam being performed for an unrelated purpose [2] [3].
Most diagnostic algorithms for patients presenting with symptoms associated with hepatic artery aneurysm (e.g. mid-epigastric discomfort, abdominal pain) include imaging. The most common imaging modalities used to evaluate hepatic artery aneurysm (and generalized abdominal pain) are ultrasound scan (US), computed tomography (CT) scan with contrast, and angiogram.
On the US, a hepatic artery aneurysm may appear as a mixed echogenic mass with cystic and solid components. Calcifications are usually present in the wall of an aneurysm [5] [6]. Color doppler will demonstrate turbulent or arterial pulsatile flow that is suggestive of the lesion being vascular in origin. US can be used to rule out other vascular conditions such as arteriovenous malformations or fistulas [7] [8] [9].
Hepatic artery aneurysm can be diagnosed by a contrast-enhanced CT scan or three-dimensional CT scan. In general, a CT scan will demonstrate the characteristics of an aneurysm, adjacent anatomical structures, and any signs of rupture. Calcifications will usually be present in the vessel's wall. Thrombotic deposits in the vessel's lumen appear as ring-shaped or semilunar areas of hypodensity. Intravenous contrast allows a more definitive view of the vessel lumen.
A CT angiogram is able to further delineate small aneurysms and provide anatomical details including identification of the artery of origin. Use of CT angiogram often provides a definitive diagnosis, without the need of angiography, however, intravenous contrast is contraindicated in some patients with renal dysfunction [10] [11].
Three-dimensional contrast-enhanced magnetic resonance imaging (MRI) angiography may also be used for the diagnosis of hepatic artery aneurysm in lieu of angiography. Three-dimensional MRI is a quick, sensitive, accurate test and it provides better delineation of the arterial anatomy [12] [13].
Angiography is considered the gold standard diagnostic test for hepatic artery aneurysm. It is highly efficacious with a sensitivity of 100% [13]. Angiography, while invasive, permits diagnosis, identification of additional aneurysms, feeding vessels, and provides information necessary for treatment of an aneurysm [14].