PT  - JOURNAL ARTICLE
AU  - Vogt, Florian M.
AU  - Antoch, Gerald
AU  - Veit, Patrick
AU  - Freudenberg, Lutz S.
AU  - Blechschmid, Nina
AU  - Diersch, Olaf
AU  - Bockisch, Andreas
AU  - Barkhausen, Jörg
AU  - Kuehl, Hilmar
TI  - Morphologic and Functional Changes in Nontumorous Liver Tissue After Radiofrequency Ablation in an In Vivo Model: Comparison of <sup>18</sup>F-FDG PET/CT, MRI, Ultrasound, and CT
AID  - 10.2967/jnumed.107.042846
DP  - 2007 Nov 01
TA  - Journal of Nuclear Medicine
PG  - 1836--1844
VI  - 48
IP  - 11
4099  - http://jnm.snmjournals.org/content/48/11/1836.short
4100  - http://jnm.snmjournals.org/content/48/11/1836.full
SO  - J Nucl Med2007 Nov 01; 48
AB  - Rimlike contrast enhancement on morphologic imaging and increased tracer uptake on 18F-FDG PET in the periphery of the necrosis can hamper differentiation of residual tumor from regenerative tissue after radiofrequency ablation of liver lesions. This study used MRI, CT, ultrasound, and 18F-FDG PET/CT to assess the typical appearance of lesions in nontumorous animal liver tissue after radiofrequency ablation. Methods: Lesions were created by radiofrequency ablation of normal liver parenchyma in 21 minipigs. Follow-up was performed by 3 contrast-enhanced morphologic modalities—MRI, CT, and ultrasound—and by 18F-FDG PET/CT immediately, 3 and 10 d, and 1, 2, 3, and 6 mo after radiofrequency ablation. Images were evaluated qualitatively for areas of increased enhancement and regions of elevated tracer uptake. Furthermore, all images were assessed quantitatively by determination of ratios comparing enhancement/tracer uptake in the periphery of the necrosis with enhancement/tracer uptake in normal liver parenchyma. Imaging findings were compared with histopathology findings. Results: Immediately after radiofrequency ablation, no increase in 18F-FDG uptake was visible, whereas elevated enhancement was noticed in the periphery of the necrosis on all morphologic imaging procedures. At further follow-up, an area of rimlike increase in 18F-FDG uptake surrounding the necrosis was detected on PET/CT. The rimlike pattern of increased enhancement in the arterial phase was present for all liver lesions on CT, MRI, and ultrasound, especially between day 3 and month 1 after the radiofrequency ablation. Both elevated glucose metabolism and enhancement persisted for 6 mo postinterventionally. Histologic examination showed a hemorrhagic border converting into a regeneration capsule. Conclusion: If performed immediately after radiofrequency ablation, 18F-FDG PET/CT probably has benefits over those of morphologic imaging procedures when assessing liver tissue for residual tumor. Later follow-up may be hampered by visualization of peripheral hyperperfusion and tissue regeneration. Further studies on a patient population are essential.