The effect of catheter-directed CT angiography on yttrium-90 radioembolization treatment of hepatocellular carcinoma

PURPOSE: Yttrium 90 radioembolization is a transcatheter therapy for unresectable hepatocellular carcinoma (HCC) that delivers internal radiation to tumors. In contrast to the usual method of lobar regional delivery, catheter-directed computed tomographic (CT) angiography was investigated as a potentially useful technique to evaluate the administration of segmental ⁹⁰Y tumor radiation doses superselectively without significantly altering liver function or Child-Pugh classification. MATERIALS AND METHODS: Fourteen patients underwent ⁹⁰Y therapy for unresectable HCC. After standard angiographic placement of a 3-F microcatheter in a segmental hepatic artery supplying the tumor, each patient underwent CT angiography with use of segmental hepatic artery injection of iodinated contrast agent to confirm segmental perfusion and delineate segmental liver volume. ⁹⁰Y was later injected into the same segmental artery. Target dose was calculated according to infused ⁹⁰Y activity and targeted hepatic volume with standard lobar volume (before CT angiography) versus segmental liver volume (after CT angiography). The Wilcoxon signed-rank test (α = 0.05) was used to compare the estimated ⁹⁰Y dose before CT angiography with the actual ⁹⁰Y dose after CT angiography, as well as changes in serum bilirubin level and Child-Pugh classification as a result of treatment. RESULTS: The mean estimated tumor dose before CT angiography (SD) was 100 Gy ± 43 (range, 35-169 Gy). The mean actual tumor dose after CT angiography was 348 Gy ± 204 (range, 105-857 Gy), which was significantly greater (P < .001). The mean bilirubin level before treatment was 1.0 mg/dL ± 0.97 (range, 0.2-4.0 mg/dL), whereas the mean bilirubin level after treatment was 1.3 mg/dL ± 0.85 (range, 0.5-3.8 mg/dL). This difference, although statistically significant (P = .03), was not clinically important. Thirteen of 14 patients had no change in Child-Pugh class. CONCLUSION: CT angiography can be used to delineate the blood supply and volume to a targeted hepatic segment, allowing superselective ⁹⁰Y radioembolization. This approach significantly increases effective ⁹⁰Y tumor radiation dose without clinically altering liver function or Child-Pugh class.