E4709. Watch Out for That Parasite: Extrahepatic Arterialization of Intrahepatic Tumors
  1. Ruchika Khot; University of Nebraska Medical Center
  2. Mark Wright; University of Nebraska Medical Center
  3. Lei Yu; University of Nebraska Medical Center
Transarterial embolization is an important locoregional therapy for unresectable primary and metastatic hepatic neoplasms. Successful treatment relies on selecting and embolizing all the vessels feeding the tumor. Although most liver tumors are supplied by hepatic arteries, up to 30% of tumors can recruit extrahepatic collateral (EHC) arteries. Focusing solely on hepatic arteries for treatment planning can lead to incomplete or ineffective treatment. Angiography of every possible EHC pathway during treatment would be cumbersome and is not always feasible. Therefore, it is important for the interventional radiologists to know when to suspect and how to look for EHC vessels in patients with liver tumors.

Educational Goals / Teaching Points
This educational exhibit reviews imaging findings associated with the presence of EHC vessels and tumor characteristics that may increase suspicion for extrahepatic arterialization. Through case presentation, we will review procedural considerations during EHC embolization and common complications.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
An important step to treat a tumor with EHC supply is to know when to suspect it. Certain image features on CT and MRI are predictive of EHC, including large tumor size, hypertrophied artery, and evidence of tumor invasion into surrounding structures. Tumors in particular locations have increased likelihood of EHC recruitment, such as the bare area of the liver, near the dome of the liver, near the kidney and other abdominal viscera. On angiogram, large peripheral tumor blush defect, smaller than expected tumor blush, poor tumor retainment of contrast, and peripheral recurrence of a treated tumor are all signs of EHC involvement. A variety of EHC have been reported, such as right and left inferior phrenic, omental, right suprarenal, right renal, right internal thoracic, intercostals, cystic, right and left gastric, lumbar, superior mesenteric, and gastroduodenal arteries. Transarterial embolization of EHC vessels can carry significant risk, as those vessels also supply vital organs. Nontarget embolization of EHC arteries can lead to serious complications. Therefore, prophylactic coil embolization of EHC branches supplying important structures is often performed. We will present three liver tumor cases, discuss imaging findings that led to the investigation of EHC arteries, and highlight procedural considerations during transarterial embolization.

Recognition of EHC arteries of liver tumors plays a key role in increasing the efficacy of transarterial treatment. Interventional radiologists need to be familiar with imaging features suggestive of parasitic blood supply and procedural techniques to avoid serious complications.