E3300. Lung Shunt Fraction Predictors and Associations with Survival in Hepatocellular Carcinoma and Liver Metastases
  1. Johnny Yang; University of Mississippi Medical Center
  2. Logan Ryals; University of Mississippi Medical Center
  3. Gregory Vance; University of Mississippi Medical Center
  4. Chanukya Cherukuri; University of Mississippi Medical Center
  5. Bradley Hathaway; University of Mississippi Medical Center
  6. John Salvemini; University of Mississippi Medical Center
  7. Vani Vijayakumar; University of Mississippi Medical Center
Hepatocellular carcinoma (HCC) is related to more than 830,000 deaths annually. Given that majority of cases present at the intermediate to advanced stage, surgery, ablation, and transplant are no longer the most common recommended treatments. Transarterial radioembolization (TARE) with Yittrium-90 (Y90) microspheres is the mainstay treatment for unresectable HCC and liver metastases. Imaging studies for these purposes typically include contrast-enhanced abdominal CT or MRI, hepatic and mesenteric angiography, and <sup>99m</sup>Tc macroaggregated albumin (MAA) scintigraphy. The current standard of care is to perform a planning angiographic study with <sup>99m</sup>Tc-MAA prior to Y90 TARE to mimic Y90 accumulation and assess splanchnic and pulmonary shunting. For resin microspheres, the manufacturer recommends dose reduction for patients with lung shunt fraction (LSF) > 10% and no treatment for patients with LSF >20%. For glass microspheres, the manufacturer recommends limiting the single treatment estimated lung dose to 30 Gy and the cumulative estimated lung dose to 50 Gy.

Educational Goals / Teaching Points
Review HCC in relation to staging, treatment strategies, and prognosis. Discuss LSF and survival in HCC and liver metastases post-Y90 TARE. Discuss TARE treatment in the presence of high LSF and the optimal threshold by Tc-MAA mapping. Highlight the predisposing factors for high LSF by Tc-MAA.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
The noninvasive predictors of increased LSF include tumor type, size, burden, neovascularity, arterioportal shunting, portal vein tumor thrombus, hepatic venous shunting, hepatic vein thrombus. LSF is a statistically significant covariate in a univariate proportional hazards model and contributes as an independent risk factor for poor survival in a multivariate model.

Increased LSF may serve as a useful preprocedural predictor of worse survival in patients with HCC or liver metastases. Tc-MAA serves as an important tool for evaluating safety prior to employing Y90 TARE.