Hepatocellular Carcinoma Tumor Dose Response following 90Y-radioembolization with glass microspheres using 90Y-SPECT/CT based Voxel Dosimetry

Publication date: Available online 2 June 2018
Source:International Journal of Radiation Oncology*Biology*Physics
Author(s): S.Cheenu Kappadath, Justin Mikell, Anjali Balagopal, Veera Baladandayuthapani, Ahmed Kaseb, Armeen Mahvash
PurposeTo investigate hepatocellular carcinoma (HCC) tumor dose-response characteristics based on voxel-level absorbed doses (D) and biological effective doses (BED) using quantitative ⁹⁰Y-SPECT/CT after ⁹⁰Y-radioembilization with glass-microspheres. We also investigated the relationship between normal liver D and toxicities.Methods⁹⁰Y-radioembolization activity distributions for 34 patients were based on quantitative ⁹⁰Y-bremsstrahlung SPECT/CT. D maps were generated using a local-deposition algorithm. Contrast-enhanced CTs or MRIs of the liver were registered to ⁹⁰Y-SPECT/CT and all tumor larger than 2.5 cm diameter (53 tumors) were segmented. Tumor mean D and BED (Dmean and BEDmean) and dose volume coverage from 0-100% in 10% steps (D0-D100 and BED0-BED100) were extracted. Tumor response was evaluated on follow-up using WHO, RECIST, and mRECIST. Differences in dose metrics for responders and non-responders were assessed using Mann-Whitney U test. Univariate logistic regression model was used to determine tumor dose metrics that correlated with tumor response. Correlations between tumor size, tumor Dmean, and tumor dose heterogeneity (defined as the coefficient of variation) were assessed.ResultsThe objective response rates were 14/53, 15/53, and 30/53 for WHO, RECIST, and mRECIST criteria, respectively. WHO and RECIST response statuses did not correlate with D or BED. D and BED between mRECIST responders and non-responders were significantly different for Dmean, D20-D80, BEDmean, and BED0-BED80. Threshold doses (and the 95% confidence interval) for 50% probability of mRECIST response (D50%) were 160 Gy (123-196 Gy) for Dmean and 214 Gy (146-280 Gy) for BEDmean. Tumor dose heterogeneity significantly correlated with tumor volume. No statistically significant association between Dmean to normal liver and complications related to bilirubin, albumin, or ascites was observed.ConclusionsHCC tumor dose-response curves following ⁹⁰Y-radioembolization with glass-microspheres showed Dmean of 160 Gy and BEDmean of 214 Gy for D50% with PPV of ∼70% and NPV of ∼62%. No complications were observed in our patient cohort for normal liver Dmean less than 44 Gy.



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