Catheter angiography is performed to establish a specific diagnosis of abdominal neoplasms and splanchnic vascular lesions (including arterial occlusive lesions, vasculitis, aneurysms and pseudoaneurysms, arteriovenous fistula, and malformations), to evaluate complications of cirrhosis and portal hypertension, to diagnose portomesenteric thrombosis, and to obtain specific information about hepatoportal hemodynamics, vascular anatomy and variation before endovascular or surgical intervention. In this chapter, the technique and use of catheter angiography in the diagnosis and management of gastrointestinal, pancreatic, hepatic, and splenic lesions are illustrated.

General angiographic technique

Gastrointestinal angiography is performed by means of percutaneous retrograde femoral arterial catheterization (Seldinger technique). The common femoral artery usually is punctured with a 21 gauge (0.032 inch) single‐wall puncture needle under ultrasound guidance. When the femoral artery cannot be used because of occlusion, the brachial or radial artery is used. Most visceral angiography is performed with 4 Fr or 5 Fr catheters with preshaped configurations. Three commonly used preshaped catheter configurations for visceral angiography are the shepherd’s hook, cobra, and sidewinder catheters.

Intraarterial digital subtraction angiography (IA DSA) is currently used for visceral angiography. Both iodinated contrast medium and carbon dioxide (CO₂) are used as contrast agents. CO₂ is the preferred contrast agent for visualization of the origins of the celiac and superior mesenteric arteries and their occlusive lesions (Figure 93.1), detection of gastrointestinal (GI) bleeding (Figure 93.2), wedged hepatic venography, bleeding from traumatic injury of the spleen and liver, and splenoportography. Because CO₂ causes no known allergic reactions or nephrotoxicity, it should be used as an alternative contrast agent in patients with hypersensitivity to iodinated contrast material or renal insufficiency. A basic knowledge of the physical properties of CO₂ (including high solubility, buoyancy, low viscosity, and compressibility) is essential in obtaining a safe and successful angiogram. Air contamination must be avoided during CO₂ delivery for angiography. CO₂ should not be used in the arterial circulation above the diaphragm. In general, the rate of injection for CO₂ angiography should be slightly greater than the expected blood flow of the vessel being injected.

The techniques used in visceral angiography are aortography, selective and superselective visceral angiography, indirect portography (arterial portography), direct portography (transhepatic, transjugular, transsplenic or transumbilical approach), hepatic venography, and wedged hepatic venography. The coaxial catheterization method using a 3 Fr microcatheter is used for superselective catheterization for embolization of GI bleeding, tumors, and vascular lesions. When visceral artery aneurysms and pseudoaneurysms cannot be accessed transarterially, percutaneous direct access using a 22 gauge Chiba needle is used for embolization therapy. Wedged hepatic venography and manometry are two of the most important techniques for the evaluation of patients with cirrhosis and portal hypertension, and hepatic venous outflow obstruction. Wedged hepatic venous pressure is measured using an end‐hole catheter or balloon occlusion, usually from the internal jugular venous approach, and is a direct reflection of sinusoidal pressure and, in the absence of presinusoidal obstruction, of portal venous pressure.

Gastrointestinal angiography

Visceral angiography often begins with lateral aortography to visualize the origins of the celiac and superior mesenteric arteries in patients suspected of having mesenteric ischemia (Figure 93.3). Visceral angiography includes injection into the celiac and superior mesenteric arteries to demonstrate vascular anatomy (Figures 93.4–93.7). Visceral angiography is used for the diagnosis of pancreatic endocrine tumors, the source of GI bleeding, traumatic bleeding, arterial occlusive disease (Figure 93.8), collateral circulation (Figure 93.9), aneurysms (Figure 93.10), arteriovenous malformations and fistulas (Figure 93.11), portal and mesenteric venous thrombosis, splenic vein thrombosis, portosystemic collateral veins, and portal vein aneurysm (Figure 93.12).

Angiography plays an important role in the diagnosis of upper and lower gastrointestinal bleeding (Figures 93.13–93.16). Angiography is especially useful in identifying chronic gastrointestinal bleeding from tumors (Figure 93.17), vascular malformations (Figure 93.18), and colonic vascular ectasia (Figure 93.19). Visualization of the portal venous system is important in the evaluation of cirrhosis and portal hypertension, and pancreatic, biliary, and hepatic tumors.

The portal vein can be evaluated by means of indirect portography (arterial portography with the injection of contrast medium in the superior mesenteric or splenic artery) (Figures 93.20 and 93.21) or direct portography (using a transhepatic, transjugular or transsplenic approach) (Figures 93.22 and 93.23). Angiography is used to differentiate occlusive from nonocclusive mesenteric ischemia. It is also useful in the diagnosis of carcinoid tumor (Figure 93.24) and both pancreatic (Figure 93.25) and hepatic (Figure 93.26) metastases. Diagnostic angiography is performed prior to balloon angioplasty of superior mesenteric artery stenosis and transcatheter embolization for control of upper and lower GI bleeding, and occlusion of splanchnic artery aneurysms and pseudoaneurysms (Figure 93.27).

Pancreatic angiography

Ultrasound, computed tomography (CT), and magnetic resonance imaging (MRI) are the initial diagnostic procedures for inflammatory and neoplastic pancreatic lesions. Endoscopic retrograde cholangiopancreatography with cytological examination is commonly performed for suspected pancreatic cancer. If endoscopy is unsuccessful in patients with a mass in the pancreatic head and obstructive jaundice, percutaneous transhepatic cholangiogram with biliary drainage is performed. Once pancreatic lesions have been demonstrated by other imaging modalities, angiography may be performed to obtain a specific diagnosis and assess the vascular anatomy and resectability of the tumor before surgical intervention.

Endoscopic ultrasound scanning is commonly used to localize pancreatic islet cell tumors. When it reveals a pancreatic mass in a patient with hyperinsulinism, surgical therapy is possible without additional localization procedures. For occult insulinomas, selective arterial calcium stimulation localizes the source of hyperinsulinism through assay of insulin from the hepatic vein at 30 s and 60 s, following stimulation of the potential supplying arteries. Angiography localizes insulinoma in approximately 60% of cases (Figure 93.28). Angiography is often negative for gastrinomas because they are usually hypovascular. However, selective secretin injection regionalizes occult gastrinomas through blood sampling from the hepatic vein at 30 s and 60 s following stimulation of the potential feeding artery. Angiography is usually positive for other neuroendocrine tumors, including vasoactive intestinal polypeptide‐secreting tumor (VIPoma), pancreatic polypeptide‐producing tumor (PPoma), somatostatinoma, and glucagonoma (Figure 93.29).

Angiography is important in the diagnosis and management of gastrointestinal bleeding complicating pancreatitis and pseudocysts (Figure 93.30). In this setting, bleeding may originate from an aneurysm or varices associated with portal or splenic venous thrombosis.

Hepatic angiography

Ultrasound, CT (with and without contrast enhancement), and MRI are used for the diagnosis of hepatic mass lesions. Angiography is sensitive in detecting vascular tumors in the liver, including hepatoma, cavernous hemangioma (Figure 93.31), focal nodular hyperplasia (Figure 93.32), and bleeding associated with hepatic adenoma (Figure 93.33).

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