Pictorial essay: imaging findings following Y90 radiation segmentectomy for hepatocellular carcinoma.

Transarterial radioembolization is a novel therapy that has gained rapid clinical acceptance for the treatment of hepatocellular carcinoma (HCC). Segmental radioembolization [also termed radiation segmentectomy (RS)] is a technique that can deliver high doses (> 190 Gy) of radiation selectively to the hepatic segment(s) containing the tumor. The aim of this comprehensive review is to provide an illustrative summary of the most relevant imaging findings encountered after radiation segmentectomy. A 62-patient cohort of Child-Pugh A patients with solitary HCC < 5 cm in size was identified. A comprehensive retrospective imaging review was done by interventional radiology staff at our institution. Important imaging findings were reported and illustrated in a descriptive account. For the purposes of completeness, specific patients outside our initial cohort with unique educational imaging features that also underwent segmentectomy were included in this pictorial essay. This review shows that response assessment after RS requires a learning curve with common drawbacks that can lead to false-positive interpretations and secondary unnecessary treatments. It is important to recognize that treatment responses and pathological changes both are time dependent. Findings such as benign geographical enhancement and initial benign pathological enhancement can easily be misinterpreted. Capsular retraction and segmental atrophy are some other examples of unique post-RS response that are not seen in any other treatment.