Dosimetry Assessment in Predicting Treatment Outcomes Following Yttrium-90 Transarterial Radioembolization of Hepatic Tumors.

Purpose: To evaluate the use of yttrium-90 (Y90) dosimetry in predicting treatment outcomes when used following transarterial radioembolization with SIR-Spheres® (Resin Y90) in patients with hepatic tumors. Materials and Methods: This single institution retrospective analysis included 100 patients with hepatocellular carcinoma, colorectal carcinoma or other liver metastases who underwent transarterial radioembolization with resin Y90 and had imaging follow-up within one year of treatment. Mean tumor dose and mean dose to nontumor was calculated using voxel-based dosimetry software. Descriptive statistics were reported and methods of analyses included simple and multivariable linear regression, contingency table analyses, Kaplan-Meier estimation, and Cox proportional hazards models. Results: Of 100 patients included, 65 demonstrated tumor shrinkage following transarterial radioembolization. Of these, 20 (30.8%) had hepatocellular carcinoma, 22 (33.8%) had colorectal carcinoma, and 23 (35.4%) had other types of metastases. There was an association between tumor shrinkage and mean tumor dose (p = 0.0285) and mean dose to nontumor (p = 0.0028) in hepatocellular carcinoma patients, but not colorectal carcinoma, or the other subgroup. For all 100 patients, time to death and mean tumor dose was associated only in the other subgroup (p = 0.0260), but not in the hepatocellular or colorectal carcinoma groups. Time to death and mean dose to nontumor was associated in hepatocellular carcinoma patients (p = 0.0421), but not the colorectal carcinoma or other subgroup. Conclusions: Voxel-based dosimetry assessment is a tool that may be utilized to assist in predicting treatment outcomes in responders to transarterial radioembolization.