May be of interest to the medcos....

May be of interest to the medcos.

http://www.sciencedirect.com/science/article/pii/S2211568415004027

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Hepatopulmonary shunt reduction with bland embolization for yttrium-90 radioembolization

• N. Kwok^{a, ,} ,
• Z. Irani^b, ,
• R. Sheth^b, ,
• R.S. Arellano^b,

Dear Editor,
Uveal melanoma is the most common primary intraocular malignancy in adults, and often metastasizes to the liver. Radioembolization with yttrium-90 is a treatment option, but is contraindicated when hepatopulmonary shunt fractions are greater than 20% [1] and [2]. We present a case of successful radioembolization of metastatic uveal melanoma following reduction of hepatopulmonary shunt fraction of more than 20%.
A 64-year-old man with uveal melanoma developed bilateral hepatic metastases measuring up to 12 × 10 cm. The patient refused surgical resection, but agreed to undergo radioembolization with yttrium-90. Initial hepatic arteriography revealed a modal distribution of the hepatic vasculature with the right branch of the hepatic artery arising from the proper hepatic artery. The cystic artery arose from the proper hepatic artery and the right gastric artery from the common hepatic artery. Selective catheterization of the right branch of the hepatic artery showed abnormal vascularity consistent with tumors in segments 5 and 6 but no obvious shunting. Coil embolization of the gastroduodenal artery was performed, followed by administration of 4.18 mCi technetium-99 m macroaggregated albumin (^99mTc-MAA). Single photon emission computed tomography (SPECT) revealed bilateral pulmonary uptake of ^99mTc-MAA and a calculated shunt fraction of 34.4% (Fig. 1). Reduction of the total radiation dosage was considered but denied due to concerns of delivering subtherapeutic levels of yttrium-90. Therefore, an attempt was made to decrease the shunt fraction using bland embolization. Selective partial embolization of the right branch of the hepatic artery was performed with approximately 1/5 vial of 500–700 μm Embospheres^® (Merit Medical System, South Jordan, Utah, USA). Selection of 500–700 μm particles was decided in part according to Mei and Li [3]. Because a shunt was not identified at the time of angiography, we considered the shunt to be high flow and intratumoral (Fig. 2). The use of 1/5 vial was based on the desired goal of reducing shunt fraction while maintaining vascular patency for subsequent radioembolization. Post-embolization angiography showed reduction in tumor vascularity and reduction of the hepatopulmonary shunt fraction to 5.7% (Fig. 3). This allowed subsequent radioembolization of the right branch of the hepatic artery with 49.94 mCi of Yttrium 90 coated SIRTeX^®, SIR-spheres (Sirtex, Wilmington, MA, USA). One month later PET-CT imaging demonstrated decrease in tumor size and reduction in fluorodeoxyglucose (FDG) uptake when compared to baseline PET-CT. Twelve months post radioembolization repeat PET-CT revealed continued decrease in tumor size, absence of FDG activity in the treated tumors and no new lesions in the chest, abdomen or pelvis.

Figure 1.
64-year-old man with uveal melanoma metastatic to the liver. Static images of the right anterioposterior projection of the liver (a), and the chest (b) from ⁹⁹Tc MAA scan demonstrate 34% shunt fraction to the lung.
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Figure 2.
Static images of the right anterioposterior projection of the liver (a) and the chest (b) from ⁹⁹Tc MAA scan demonstrate 5.7% shunt fraction after bland embolization.
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Figure 3.
Celiac axis arteriogram shows hepatic vasculature and vascularization of hepatic metastases from uveal melanoma. Arrows indicate dominant metastatic lesion in the right liver.
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Yttrium-90 radioembolization is increasingly used to treat primary and metastatic liver tumors. It is contraindicated when hepatopulmonary shunt fractions are greater than 20% [1] and [2]. Arteriovenous shunting between the hepatic arterial circulation and systemic venous system occurs within tumors due to their immature vascular tree and lack of organized capillary beds. Radioembolization of tumors with high hepatopulmonary shunt fractions can result in high radiation exposure to the lungs, leading to radiation pneumonitis because the lung is a very radiation sensitive organ. No clear guidelines exist for rectifying situations for patients with an unacceptably high level of hepatopulmonary shunting. While previous reports have described the use of chemoembolization or drug eluting beads to reduce shunt fractions [4] and [5], the types and amount of embolic agents necessary to achieve successful shunt reduction are not clearly defined. Further investigation on the optimal method of shunt reduction is warranted in order to fully understand the safety and clinical outcomes of shunt reduction prior to radioembolization. This case highlights the effectiveness of bland embolization to successfully reduce an elevated hepatopulmonary shunt fraction to a level that allowed subsequent radioembolization of metastatic uveal melanoma.
Disclosure of interest

The authors declare that they have no competing interest.