title: Central lower attenuating lesion in the ablation zone on immediate follow-up CT after percutaneous radiofrequency ablation for hepatocellular carcinoma: incidence and clinical significance.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the incidence of central lower attenuating (CLA) lesion in the ablation zone seen on immediate follow-up CT images after percutaneous radiofrequency ablation (RFA) for hepatocellular carcinoma (HCC), and the correlation of CLA lesions and local tumor progression (LTP).
  
  
  METHODS
  The study group included 146 patients with 167 ablation zones that had undergone follow-up CT examinations for more than 12 months after percutaneous RFA. CLA lesions corresponding to index tumors and ablative margins (safety margins) were evaluated in the ablation zones seen on immediate follow-up CT including coronal and sagittal multiplanar reformatted (MPR) images with narrow window width settings.
  
  
  RESULTS
  CLA lesions were depicted on 48 of 167 ablation zones (28.7%) on immediate follow-up CT images. Among the 48 ablation zones with CLA lesions, 27 (56.3%, 27/48) had ablative margins on all three of the orthogonal MPR images and they showed no LTP (0%) on follow-up CT examinations. Three of the ablation zones with CLA lesions (6.3%, 3/48) having an ablative margin on one plane only also showed no LTP (0%). LTP was observed in 2 of 18 ablation zones (11.1%) that had CLA lesions without ablative margins on all three planes. In the remaining 119 ablation zones without CLA lesions, 5 (4.2%, 5/119) showed LTP.
  
  
  CONCLUSIONS
  CLA lesions in ablation zones were occasionally (28.7%) seen on immediate follow-up CT images after RFA for HCCs. The presence of CLA lesions with ablative margins might be a negative predictor of LTP.
authors.affiliation: Department of Radiology, Samsung Medical Center, Sungkyunkwan University School of Medicine, #50, Ilwon-dong, Gangnam-gu, Seoul 135-710, Republic of Korea.
authors.forename: Yulri
authors.initials: Y
authors.lastname: Park
authors.forename: Dongil
authors.initials: D
authors.lastname: Choi
authors.forename: Hyunchul
authors.initials: H
authors.lastname: Rhim
authors.forename: Young-sun
authors.initials: YS
authors.lastname: Kim
authors.forename: Ji Young
authors.initials: JY
authors.lastname: Lee
authors.forename: Ilsoo
authors.initials: I
authors.lastname: Chang
authors.forename: Hyo K
authors.initials: HK
authors.lastname: Lim
authors.forename: Cheol Keun
authors.initials: CK
authors.lastname: Park
mesh_terms: D000328:Adult; D000368:Aged; D002058:Burns, Electric / Q000453:epidemiology*; D006528:Carcinoma, Hepatocellular / Q000000981:diagnostic imaging* / Q000601:surgery*; D017115:Catheter Ablation; D015897:Comorbidity; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D007723:Korea / Q000453:epidemiology; D008113:Liver Neoplasms / Q000000981:diagnostic imaging* / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000453:epidemiology*; D012307:Risk Factors; D014057:Tomography, X-Ray Computed / Q000706:statistics & numerical data*