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

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Okuma, T. Articles by Inoue, Y. Search for Related Content PubMed PubMed Citation Articles by Okuma, T. Articles by Inoue, Y.

¹⁸F-FDG Small-Animal PET for Monitoring the Therapeutic Effect of CT-Guided Radiofrequency Ablation on Implanted VX2 Lung Tumors in Rabbits

¹ Department of Radiology, Osaka City University Graduate School of Medicine, Osaka, Japan; ² Saiseikai Nakatsu PET Center, Osaka, Japan; ³ Department of Physiology, Osaka City University Graduate School of Medicine, Osaka, Japan; and ⁴ Frontier Research System, RIKEN, Tokyo, Japan

Correspondence: For correspondence or reprints contact: Tomohisa Okuma, MD, Department of Radiology, Osaka City University Graduate School of Medicine, 1-4-3 Asahimachi, Abeno-ku, Osaka 545-8585, Japan. E-mail: o-kuma{at}msic.med.osaka-cu.ac.jp

The primary goals of this study were to investigate the behavior of normal lung tissues after radiofrequency ablation (RFA) and to determine the suitability of ¹⁸F-FDG PET, using a dedicated small-animal scanner, for monitoring the early therapeutic effects of RFA on VX2 lung tumors (VX2s) in rabbits. Methods: Fourteen Japanese white rabbits with normal lungs underwent RFA, followed by ¹⁸F-FDG PET at 1 d and at 1, 2, 4, and 8 wk. In addition, 7 rabbits with untreated VX2s underwent ¹⁸F-FDG PET, and 13 rabbits with RFA-treated VX2s underwent ¹⁸F-FDG PET at 1 d (n = 7) or 1 wk (n = 6) after the treatment. Results: After RFA of normal lungs, ring-shaped accumulations of ¹⁸F-FDG, which coincided with inflammation caused by ablation, were observed. The mean early- (40–60 min after injection) and delayed (100–120 min)-phase ablated lesion-to-muscle ratios were, respectively, 2.9 ± 1.0 and 3.3 ± 0.8 (1 d), 4.1 ± 0.6 and 5.2 ± 0.9 (1 wk), 4.1 ± 1.0 and 5.3 ± 1.5 (2 wk), 3.1 ± 0.5 and 3.6 ± 1.1 (4 wk), and 1.8 ± 0.1 and 2.3 ± 0.1 (8 wk). At 4 and 8 wk, the uptake was less than that at 1 and 2 wk (P < 0.05). VX2s showed mean tumor-to-muscle ratios of 6.6 ± 2.1 and 8.6 ± 3.3 at the early and delayed phases, respectively. For ablated tumors, the respective ratios were 0.8 ± 0.4 and 1.1 ± 0.7 (1 d) and 1.2 ± 0.5 and 1.5 ± 0.7 (1 wk). These values were significantly lower than those for nonablated tumors (P < 0.001). Histopathologic examination confirmed the absence of viable tumors. ¹⁸F-FDG accumulation around ablated tumors reflected thermally damaged normal tissues and was significantly lower than that of control VX2s (P < 0.01). Conclusion: Our data suggest that ¹⁸F-FDG PET is promising for evaluating the therapeutic response of lung malignancies to RFA: Accumulation of ¹⁸F-FDG in surrounding normal tissues appears to be time dependent, and the data suggest that, clinically, ¹⁸F-FDG PET should be performed 4 wk or more after RFA. Delayed-phase images seem to better distinguish tumor from inflammation than do early-phase images.

Key Words: radiofrequency ablation • microPET • lung • animal model • VX2 carcinoma

This article has been cited by other articles:

				N. Avril 18F-FDG PET After Radiofrequency Ablation: Is Timing Everything? J. Nucl. Med., August 1, 2006; 47(8): 1235 - 1237. [Full Text] [PDF]