REGULAR CONTENT
Final ID
498
Type
Original Scientific Research-Oral or Pos
Authors
A Pasciak1, A Lin2, C Georgiades3, L Findeiss4, S Kauffman5, A Bourgeois6, Y Bradley7
Institutions
1Johns Hopkins School of Medicine, Baltimore, MD, 2The Johns Hopkins School of Medicine, Baltimore, MD, 3JOHNS HOPKINS UNIVERSITY, BALTIMORE, MD, 4University of Tennessee Graduate School of Medicine, Knoxville, TN, 5N/A, Dayton, OH, 6Medical University of South Carolina, mount pleasant, SC, 7University of Tennessee Graduate School of Medicine, knoxville, TN
Purpose
90Y PET/CT post-radioembolization imaging has demonstrated that the distribution of 90Y in the tumor can be non-uniform. Using computational modeling, we predicted the dosimetric impact of post-treatment 90Y PET/CT-guided percutaneous ablation of the portions of tumor receiving the lowest absorbed-dose.
Materials & Methods
14 patients with non-resectable liver cancer treated using 90Y glass or resin microspheres were included in this retrospective study. Each patient exhibited potentially under-treated areas of tumor following treatment based on quantitative 90Y PET/CT. 90Y PET/CT was used to guide electrode placement for simulated adjuvant radiofrequency ablation in areas of tumor receiving the lowest dose. The finite element method was used to solve Penne's bioheat transport equation, coupled with the Arrhenius thermal cell-death model to determine 3D thermal ablation zones. Tumor absorbed-dose metrics (average dose, D50, D70, D90, V100) were compared with and without adjuvant ablation, where D70 is the minimum dose to 70% of tumor and V100 is the fractional tumor volume receiving more than 100Gy. The paired-sample T-test and linear regression analysis were used to confirm statistical significance and evaluate correlation between dosimetry and disease characteristics.
Results
Compared to radioembolization alone, 90Y radioembolization with simulated adjuvant ablation was associated with increases in all tumor dose metrics evaluated. The mean average absorbed-dose increased by 11.2±6.9 Gy. Increases in D50, D70 and D90 were 11.0±6.9 Gy, 13.3±10.9 Gy and 11.8±10.8 Gy, respectively. The mean increase in V100 was 7.2±4.2%. All changes were statistically significant (P<0.01). A negative correlation between pre-ablation tumor volume and D50, average dose and V100 was identified (ρ<-0.5, P<0.05) suggesting that adjuvant percutaneous ablation may be less beneficial to patients with large tumor burdens.
Conclusions
This study has demonstrated that adjuvant 90Y PET/CT-guided radiofrequency ablation may improve tumor absorbed-dose metrics. These data may justify a prospective clinical trial to evaluate this hybrid approach in-vivo.
Final ID
498
Type
Original Scientific Research-Oral or Pos
Authors
A Pasciak1, A Lin2, C Georgiades3, L Findeiss4, S Kauffman5, A Bourgeois6, Y Bradley7
Institutions
1Johns Hopkins School of Medicine, Baltimore, MD, 2The Johns Hopkins School of Medicine, Baltimore, MD, 3JOHNS HOPKINS UNIVERSITY, BALTIMORE, MD, 4University of Tennessee Graduate School of Medicine, Knoxville, TN, 5N/A, Dayton, OH, 6Medical University of South Carolina, mount pleasant, SC, 7University of Tennessee Graduate School of Medicine, knoxville, TN
Purpose
90Y PET/CT post-radioembolization imaging has demonstrated that the distribution of 90Y in the tumor can be non-uniform. Using computational modeling, we predicted the dosimetric impact of post-treatment 90Y PET/CT-guided percutaneous ablation of the portions of tumor receiving the lowest absorbed-dose.
Materials & Methods
14 patients with non-resectable liver cancer treated using 90Y glass or resin microspheres were included in this retrospective study. Each patient exhibited potentially under-treated areas of tumor following treatment based on quantitative 90Y PET/CT. 90Y PET/CT was used to guide electrode placement for simulated adjuvant radiofrequency ablation in areas of tumor receiving the lowest dose. The finite element method was used to solve Penne's bioheat transport equation, coupled with the Arrhenius thermal cell-death model to determine 3D thermal ablation zones. Tumor absorbed-dose metrics (average dose, D50, D70, D90, V100) were compared with and without adjuvant ablation, where D70 is the minimum dose to 70% of tumor and V100 is the fractional tumor volume receiving more than 100Gy. The paired-sample T-test and linear regression analysis were used to confirm statistical significance and evaluate correlation between dosimetry and disease characteristics.
Results
Compared to radioembolization alone, 90Y radioembolization with simulated adjuvant ablation was associated with increases in all tumor dose metrics evaluated. The mean average absorbed-dose increased by 11.2±6.9 Gy. Increases in D50, D70 and D90 were 11.0±6.9 Gy, 13.3±10.9 Gy and 11.8±10.8 Gy, respectively. The mean increase in V100 was 7.2±4.2%. All changes were statistically significant (P<0.01). A negative correlation between pre-ablation tumor volume and D50, average dose and V100 was identified (ρ<-0.5, P<0.05) suggesting that adjuvant percutaneous ablation may be less beneficial to patients with large tumor burdens.
Conclusions
This study has demonstrated that adjuvant 90Y PET/CT-guided radiofrequency ablation may improve tumor absorbed-dose metrics. These data may justify a prospective clinical trial to evaluate this hybrid approach in-vivo.