Lack of Portovenous Phase Washout of Hepatocellular Carcinoma as a Predictor of Incomplete Lipiodol Uptake after Transarterial Chemoembolization

Purpose: To assess the value of absent portovenous phase washout in predicting incomplete radiologic response to Transarterial Chemoembolization (TACE).Patients and Methods: Forty seven patients with Hepatocellular Carcinomas (HCCs) were assessed for its distribution of lipiodol after TACE. Multiphase Computed Tomography (CT) was done one month after TACE to assess radiologic response.Results: Twenty five HCC lesions in 25 patients showed portal washout (53%), 2 HCC lesions in two patients displayed portal isodensity (4.5%), and 20 HCC lesions in 20 patients showed portal hypervascularity (42.5%). Using Response Evaluation Criteria in Solid Tumors (mRECIST) guidelines, complete response was noted in 27.7%, partial response in 53.2%, stable disease in 19.1% and progressive disease in 0%, one month after TACE. Only 18.1% of HCC with absent portal washout showed complete response. The lack of washout in portovenous phase predicts the presence of lipiodol defects with positive predictive value, prevalence weighted positive likelihood ratio, post test probability of a positive test and odd ratio of 81.8% [95% Confidence interval (CI): 61.5-92.7], 4.49 [95% CI:1.8-11.2], 92.2% and 11.8:1 respectively. The most common pattern of lipiodol deposition is heterogeneous that seen in 59.5% of lesions.Conclusion: Lack of portovenous phase washout is a strong predictor of incomplete radiologic response to TACE. These data has clinical implications regarding the decision to do TACE for aggressive tumors in patients showing borderline liver functions and performance status.