Growth rate of new hepatocellular carcinoma after percutaneous radiofrequency ablation: evaluation with multiphase CT.
OBJECTIVE
The purpose of this study was to evaluate with serial follow-up CT examinations the growth rate of new hepatocellular carcinoma (HCC) developing after percutaneous radiofrequency ablation and to determine an appropriate follow-up interval for imaging.


METHODS
Sixty-two new HCCs appearing after percutaneous radiofrequency ablation in 59 patients who underwent follow-up multiphase CT were retrospectively identified. The volume of the new HCCs at follow-up CT was measured on a PACS monitor with an area measuring tool and summation-of-areas technique. We calculated tumor volume doubling time and tumor diameter doubling time. The growth rate was represented by tumor volume doubling time. We also used stepwise multiple linear regression analysis to evaluate the relation between clinical variables and tumor volume doubling time.


RESULTS
Mean baseline and follow-up tumor volumes were 580 mm(3) (range, 85-13,861 mm(3)) and 2,072 mm(3) (range, 535-35,937 mm(3)). Mean baseline and follow-up tumor diameters were 9.9 mm (range, 5.5-29.8 mm) and 15.0 mm (range, 10.1-40.9 mm). Mean tumor volume and tumor diameter doubling times were 75 days (range, 21-209 days) and 219 days (range, 57-897 days). Volume doubling times of baseline tumors with a diameter of 1 cm or less were significantly shorter than those of the larger baseline tumors (mean, 55 vs 88 days; p = 0.024).


CONCLUSIONS
The growth rate of new HCCs after percutaneous radiofrequency ablation was higher than that reported in natural outcome studies of untreated HCCs. The results of our study suggest that a shorter follow-up interval for imaging, 2.5 months (75 days), is appropriate.
Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, 50 Ilwon-Dong, Kangnam-Ku, Seoul 135-710, Republic of Korea.
Yulri
Y
Park
Dongil
D
Choi
Hyo K
HK
Lim
Hyunchul
H
Rhim
Young-Sun
YS
Kim
Seong Hyun
SH
Kim
Won Jae
WJ
Lee
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D006528:Carcinoma, Hepatocellular / Q000000981:diagnostic imaging* / Q000601:surgery*; D017115:Catheter Ablation / Q000379:methods*; D005260:Female; D006801:Humans; D008113:Liver Neoplasms / Q000000981:diagnostic imaging* / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000000981:diagnostic imaging* / Q000517:prevention & control*; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D014057:Tomography, X-Ray Computed / Q000379:methods*; D016896:Treatment Outcome