Hideo Gobara MD, Presenter: Nothing to Disclose

Takao Hiraki MD, Abstract Co-Author: Nothing to Disclose

Hiroyasu Fujiwara MD, PhD, Abstract Co-Author: Nothing to Disclose

Nobuhisa Tajiri MD, Abstract Co-Author: Nothing to Disclose

Jun Sakurai, Abstract Co-Author: Nothing to Disclose

Susumu Kanazawa MD, Abstract Co-Author: Nothing to Disclose

Hidefumi Mimura MD, Abstract Co-Author: Nothing to Disclose

Kotaro Yasui MD, Abstract Co-Author: Nothing to Disclose

et al, Abstract Co-Author: Nothing to Disclose

et al, Abstract Co-Author: Nothing to Disclose

To report CT imaging features of the lung tumors with and without local tumor progression after radiofrequency (RF) ablation.

From Jun 2001 to December 2005, five hundred and fifty nine tumors in 196 patients were treated with RF ablation. Among these tumors, no local tumor progression was confirmed in 47 tumors more than 24 months after RF ablation (range, 24-59 months; mean, 32 months), whereas local tumor progression was demonstrated in 81 tumors 3-30 months (mean 10 months) after RF ablation. These 126 tumors in 72 patients (46 men and 26 women, mean age 63 years; range 36-84 years) were included in this study. CT features of the tumors at 6, 12, 24 months after RF ablation were classified into 3 groups according to morphologic appearance: "Round (round or lobulated shape)", "Band (band or star-like shape)", and "Linear (linear or stellate shape with little tumor volume)". Further, CT features of the tumors at the time of local tumor progression were classified into 3 groups: "Round", "Satellite", and "Signet-ring".

The tumors with no local tumor progression showed "Round" in 13 tumors, "Band" in 18, "Linear" in 6 at 6 months after RF ablation, and "Round" in 4 tumors, "Band" in 8, "Linear" in 33 at 24 months. The tumors with local tumor progression showed "Round" in 55 tumors, "Band" in 9, "Linear" in 3 at 6 months. "Band" and "Linear" shape were more frequently (p<0.01) observed in the tumors with no local tumor progression. CT images at the time of local tumor progression showed "Round" in 59 tumors, "Satellite" in 18, "Signet-ring" in 4. Among the 34 tumors that were demonstrated with "Linear" shape during follow-up period, only four tumors (12%) showed local tumor progression, and 3 of the 4 showed "Satellite" shaped progression.

The tumor with no local tumor progression tended to shrink over time. Round-shaped tumor should be carefully observed because of a higher risk of local tumor progression, and "Linear" shaped tumor rarely showed local tumor progression, but still should be given attention to develop "satellite" shaped progression.

Morphological appearance of CT image can be a predictor of local tumor progression after RF ablation for lung tumors.

Gobara, H, Hiraki, T, Fujiwara, H, Tajiri, N, Sakurai, J, Kanazawa, S, Mimura, H, Yasui, K, et al, , et al, , CT Imaging Findings after Radiofrequency Ablation for Lung Tumors: Morphological Features of the Tumors with and without Local Tumor Progression.  Radiological Society of North America 2007 Scientific Assembly and Annual Meeting, November 25 - November 30, 2007 ,Chicago IL. http://archive.rsna.org/2007/5007723.html