Abstract No. 359 - Management of high hepatopulmonary shunt fractions in patients undergoing radioembolization

Abstract

Purpose Consensus guidelines dictate that patients with high hepatopulmonary shunt fractions should not undergo Y-90 radioembolization (RE), or should have administered activity reduced 20-40% to decrease the risk of radiation pneumonitis. We reviewed our experience of managing and treating patients with high shunt fractions. Materials and Methods We retrospectively reviewed 247 patients treated from 2004-11. We calculated pulmonary radiation dose based on technetium macroaggregated albumin (TcMAA) scintigraphy, and reviewed dose calculations and reductions as well as adjunctive prophylactic techniques utilized to reduce lung exposure during the delivery of RE microspheres. Results A total of 50/247 patients (20%) had shunt fractions > 10%. Glass microspheres were used to treat 20 and resin to treat 30 patients. 18 patients were treated with recommended dose reduction only. 4 patients with high shunt fractions (25-44%) were treated prior to RE with bland embolization and/or sclerosis, and repeat TcMAA scintigraphy demonstrated median shunt reduction of 34% (range 0 - 51%). 15 patients (including these 4) were treated using various prophylactic techniques such as hepatic vein balloon occlusion, variceal embolization, and bland arterial embolization before or during RE delivery, and 10/15 received full dose without reduction. An additional 17 patients received no dose reduction or adjuvant maneuvers because the calculated lung dose was well below 30 Gy. Of the 50 patients, only 7 would have received calculated lung exposures > 30 Gy without dose adjustment. Calculated median expected lung dose for the prophylactic treatment group was 16 Gy (range 8-68 Gy). In follow up, 1 heavily pretreated patient developed radiation pneumonitis requiring corticosteroid therapy (shunt 28%, lung exposure 16 Gy). Conclusion Standard recommendations for RE dose reductions for high hepatopulmonary shunt fractions are not mathematically justifiable, may compromise therapeutic efficacy in the liver, and are most often avoidable without substantial increase in risk. Shunting high enough to exceed the 30 Gy pulmonary threshold can be reduced by adjunctive techniques.