title: Intrahepatic distant recurrence following complete radiofrequency ablation of small hepatocellular carcinoma: risk factors and early MRI evaluation.
abstract: BACKGROUND
  Radiofrequency ablation (RFA) is related to a high intrahepatic distant recurrence (IDR) rate, and the associations between IDR and relevant imaging features have not yet been fully investigated. This study aimed to determine both clinical and imaging risk factors of IDR after complete RFA for HBV-related small hepatocellular carcinoma (HCC) (≤ 3 cm).
  
  
  METHODS
  Thirty-five patients (29 men and 6 women; mean age 60.7 years) with 40 HBV-related small HCCs who underwent complete RFA were included in our study. The incidence and potential clinical and MR imaging risk factors for IDR after RFA were assessed using the Kaplan-Meier method, the log-rank test and a stepwise Cox hazard model.
  
  
  RESULTS
  The median follow-up period was 25 (4-45) months, and IDR was observed in 20 (57.1%) patients. The 12- and 24-month cumulative IDR-free survival rates were 76.7% and 61.3%, respectively. Univariate analysis revealed that pretreatment albumin < 3.5 g/dL (P = 0.026), multinodular tumor (P = 0.032), ablative margin < 3 mm (P = 0.007), no or disrupted periablational enhancement within 24 hours (P = 0.001) and at 1 month (P = 0.043) after RFA, and hyperintensity of the central ablative zone on T1-weighted images (T1WI) at 1 month after RFA (P = 0.004) were related to IDR. Multivariate analysis showed that pretreatment albumin < 3.5 g/dL (P = 0.032), multinodular tumor (P = 0.012), no or disrupted periablational enhancement within 24 hours after RFA (P = 0.001), and hyperintensity of the central ablative zone on T1WI at 1 month after RFA (P = 0.003) were independent risk factors for IDR. During the 1-month follow-up, the apparent diffusion coefficient exhibited an up-and-down evolution without significant value in the prediction of IDR following RFA.
  
  
  CONCLUSIONS
  Patients with HBV-related small HCC had a high IDR rate after RFA. The risk factors included low serum albumin, multiple nodules, lesions with no or disrupted periablational enhancement and persistent hyperintensity in the central ablative zone on T1WI within 1 month after RFA.
authors.affiliation: Department of Radiology, Zhongshan Hospital, Fudan University; Shanghai Institute of Medical Imaging; Department of Medical Imaging, Shanghai Medical College, Fudan University, Shanghai 200032, China. zeng.mengsu@zs-hospital.sh.cn.
authors.forename: Ruo-Fan
authors.initials: RF
authors.lastname: Sheng
authors.forename: Meng-Su
authors.initials: MS
authors.lastname: Zeng
authors.forename: Zheng-Gang
authors.initials: ZG
authors.lastname: Ren
authors.forename: Sheng-Long
authors.initials: SL
authors.lastname: Ye
authors.forename: Lan
authors.initials: L
authors.lastname: Zhang
authors.forename: Cai-Zhong
authors.initials: CZ
authors.lastname: Chen
mesh_terms: D000328:Adult; D000368:Aged; D006528:Carcinoma, Hepatocellular / Q000473:pathology / Q000601:surgery* / Q000821:virology; D017115:Catheter Ablation / Q000009:adverse effects; D016208:Databases, Factual; D018572:Disease-Free Survival; D055088:Early Detection of Cancer / Q000379:methods*; D005260:Female; D006509:Hepatitis B / Q000150:complications; D006801:Humans; D053208:Kaplan-Meier Estimate; D008113:Liver Neoplasms / Q000473:pathology / Q000601:surgery* / Q000821:virology; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009364:Neoplasm Recurrence, Local; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D012307:Risk Factors; D013997:Time Factors; D016896:Treatment Outcome; D047368:Tumor Burden