Hayden Wilson Head MD, Presenter: Research grant, Tyco Healthcare (Valleylab), Boulder, CO

Gerald Dewey Dodd MD, Abstract Co-Author: Stock options, RITA Medical Systems, Inc, Mountain View, CA

Ande Bao PhD, Abstract Co-Author: Nothing to Disclose

Beth A. Goins PhD, Abstract Co-Author: Nothing to Disclose

William T. Phillips MD, Abstract Co-Author: Nothing to Disclose

To determine, using small animal SPECT (micro-SPECT), if RF ablation increases uptake of IV-administered Tc-99m radiolabeled liposomal doxorubicin (Doxil®) in xenografts of human tumors compared with IV Tc-99m-Doxil alone, and to depict the zone of radiopharmaceutical accumulation, as the initial step of an NCI Image-Guided Intervention Supplemental Award project.

Single tumors (human head and neck SCC-4 squamous cell carcinoma) were grown in the dorsal neck of male athymic nude rats to a mean diameter of 1.7 cm. Animals were treated with IV Tc-99m-Doxil and immediate RF tumor ablation at 70±1°C for 5 min (n=7), or with IV Tc-99m-Doxil alone (n=3). Micro-SPECT was performed at 0, 4, and 20 h after therapy. In a second phase of the study, rats (n=2) were implanted with 2 tumors each; only one tumor was ablated after IV Tc-99m-Doxil, and micro-SPECT was performed. After imaging, biodistribution in excised tumors of all animals was analyzed. Radiopharmaceutical uptake, as assessed by biodistribution and imaging, was characterized and compared.

In the first phase of the study, mean (±SD) uptake was 0.979% (±0.223%) per g/tissue and 2.099% (±0.626%) per tumor after treatment with combination RF ablation and IV Tc-99m-Doxil, versus 0.388% (±0.056%) per g/tissue and 0.842% (±0.225%) per tumor after IV Tc-99m-Doxil alone (p=0.0008 and 0.001, respectively). In the second phase, despite small sample size, difference in uptake was substantial and approached significance. In both phases, visual and quantitative analysis of micro-SPECT images at all time points confirmed greater uptake in RF ablation-treated tumors. Furthermore, images enabled visual inspection of the zone of radiopharmaceutical accumulation in the region of ablated tumors.

RF ablation increases uptake of IV-administered Tc-99m-Doxil in tumors compared to those treated with IV Tc-99m-Doxil alone, and micro-SPECT can be useful for evaluation of radiopharmaceutical uptake in ablated tumors.

Combination therapy with therapeutic radiopharmaceuticals may be able to potentiate tumor ablation in patients, and enable imaging methods that may be useful to assess treatment response.

Head, H, Dodd, G, Bao, A, Goins, B, Phillips, W, Micro-SPECT Imaging of Combination Radiofrequency Ablation and Intravenous Tc-99m–labeled Liposomal Doxorubicin: Preliminary Results—Increased Radiopharmaceutical Uptake in Human Tumor Xenografts.  Radiological Society of North America 2006 Scientific Assembly and Annual Meeting, November 26 - December 1, 2006 ,Chicago IL. http://archive.rsna.org/2006/4435309.html