HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Figures Only Full Text Full Text (PDF) All Versions of this Article: jnumed.108.052886v1 49/10/1723    most recent Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Related articles in JNM Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Bao, A. Articles by Phillips, W. T. PubMed PubMed Citation Articles by Bao, A. Articles by Phillips, W. T.

Real-Time Iterative Monitoring of Radiofrequency Ablation Tumor Therapy with ¹⁵O-Water PET Imaging

¹ Department of Radiology, University of Texas Health Science Center at San Antonio, San Antonio, Texas; ² Department of Otolaryngology–Head and Neck Surgery, University of Texas Health Science Center at San Antonio, San Antonio, Texas; and ³ Research Imaging Center, University of Texas Health Science Center at San Antonio, San Antonio, Texas

Correspondence: For correspondence or reprints contact: William T. Phillips, Department of Radiology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Dr., MSC7800, San Antonio, TX 78229-3900. E-mail: phillips{at}uthscsa.edu

A method that provides real-time image-based monitoring of solid tumor therapy to ensure complete tumor eradication during image-guided interventional therapy would be a valuable tool. The short, 2-min half-life of ¹⁵O makes it possible to perform repeated PET imaging at 20-min intervals at multiple time points before and after image-guided therapy. In this study, ¹⁵O-water PET was evaluated as a tool to provide real-time feedback and iterative image guidance to rapidly monitor the intratumoral coverage of radiofrequency (RF) ablation therapy. Methods: Tumor RF ablation therapy was performed on head and neck squamous cell carcinoma (SCC) xenograft tumors (length, 23 mm) in 6 nude rats. The tumor in each animal was ablated with RF (1-cm active size ablation catheter, 70°C for 5 min) twice in 2 separate tumor regions with a 20-min separation. The ¹⁵O-water PET images were acquired before RF ablation and after the first RF and second RF ablations using a small-animal PET scanner. In each PET session, approximately 100 MBq of ¹⁵O-water in 1.0 mL of saline were injected intravenously into each animal. List-mode PET images were acquired for 7 min starting 20 s before injection. PET images were reconstructed by 2-dimensional ordered-subset expectation maximization into single-frame images and dynamic images at 10 s/frame. PET images were displayed and analyzed with software. Results: Pre–RF ablation images demonstrate that ¹⁵O-water accumulates in tumors with ¹⁵O activity reaching peak levels immediately after administration. After RF ablation, the ablated region had almost zero activity, whereas the unablated tumor tissue continued to have a high ¹⁵O-water accumulation. Using image feedback, the RF probe was repositioned to a tumor region with residual ¹⁵O-water uptake and then ablated. The second RF ablation in this new region of the tumor resulted in additional ablation of the solid tumor, with a corresponding decrease in activity on the ¹⁵O-water PET image. Conclusion: ¹⁵O-water PET clearly demonstrated the ablated tumor region, whereas the unablated tumor continued to show high ¹⁵O-water accumulation. ¹⁵O-water imaging shows promise as a tool for on-site, real-time monitoring of image-guided interventional cancer therapy.

Key Words: RF ablation • real-time monitoring • ¹⁵O-water • PET • cancer

COPYRIGHT © 2008 by the Society of Nuclear Medicine, Inc.

Related articles in JNM:

This Month in JNM

JNM 2008 49: 11A-12A. [Full Text]