Imaging description

The arc of Buhler is a persistent embryological communication between the proximal celiac axis and the superior mesenteric artery (SMA). It is short in length, arising from the proximal SMA and coursing vertically to anastomose with the proximal common hepatic artery. The arc of Buhler is a developmental variant, and can be present with or without associated celiac trunk stenosis. However, when present, it provides important collateral flow between the SMA and celiac trunk in the setting of celiac trunk occlusion or high-grade stenosis. Arterial phase CT angiography with the use of multiplanar reconstructions and three-dimensional volume rendered images will clearly demonstrate the anomalous vessel, which will be prominent in the setting of celiac artery disease (Figures 83.1 and 83.2).

Importance

Communication between the celiac axis, common hepatic artery, splenic artery, and the SMA known as the arc of Buhler represents a failure of embryologic regression of the ventral anastomosis between the celiac axis and the SMA. This persistent communication is seen in up to 4% of individuals. The presence of this anastomotic variant leads to a change in the normal hemodynamics of the upper visceral circulation. The size of the arc of Buhler is usually less than 2.5 mm and may be considered significant when it preferentially fills the communicating visceral branches on diagnostic angiography. The preoperative knowledge of this variant is essential for surgical planning in cases of livertransplantation, hepatic arterychemoembolization,and pancreaticoduodenal surgeriessuch asthe Whippleprocedure ortotal pancreatectomy, especially when the gastroduodenal artery needs to be ligated in the presence of celiac axis or SMA stenosis.

Typical clinical scenario

This rare variant may be incidentally seen on routine angiography for the evaluation of gastrointestinal bleed or on CT angiography performed for liver or pancreas evaluation.

Differential diagnosis

A variant of the arc of Buhler is the Kirk's arcade, which is a communication of the splenic artery with the anterior and posterior pancreaticoduodenal arcades via the dorsal pancreatic artery.