title: Small hepatocellular carcinoma treated with percutaneous RF ablation: MR imaging follow-up.
abstract: OBJECTIVE
  The purpose of our study was to determine the usefulness of MR imaging in the follow-up evaluation of small hepatocellular carcinoma lesions treated with RF ablation.
  
  
  METHODS
  The study group included 37 patients with a single hepatocellular carcinoma lesion less than 3 cm in diameter. A strict protocol required follow-up MR imaging every 6 months after RF treatment. At each follow-up visit, the findings on unenhanced and dynamic gadolinium-enhanced MR images were correlated with those on contrast-enhanced CT images and with results of fine-needle aspiration biopsy. In five patients who underwent surgical resection after the 6-month follow-up examination, comparison with histologic findings of surgical specimens was also performed.
  
  
  RESULTS
  Correct diagnosis of complete or partial tumor necrosis was made in 32 (86%) of the 37 patients with the use of unenhanced and dynamic gadolinium-enhanced MR images. Hypointensity on T2-weighted images and loss of enhancement on dynamic MR images corresponded to completely necrotic lesions in all patients. Conversely, intratumoral regions of hyperintensity on T2-weighted images and enhancement on dynamic MR images did not always correlate to residual viable tumor. MR imaging and CT findings agreed in the evaluation of therapeutic response in all patients.
  
  
  CONCLUSIONS
  Our experience confirms that MR imaging is useful for evaluating the effectiveness of RF therapy in achieving tumor regression.
authors.affiliation: Department of Radiology, Multimedica University Hospital, Milan, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Sironi
authors.forename: T
authors.initials: T
authors.lastname: Livraghi
authors.forename: F
authors.initials: F
authors.lastname: Meloni
authors.forename: F
authors.initials: F
authors.lastname: De Cobelli
authors.forename: C
authors.initials: C
authors.lastname: Ferrero
authors.forename: A
authors.initials: A
authors.lastname: Del Maschio
mesh_terms: D000368:Aged; D001707:Biopsy, Needle / Q000295:instrumentation; D006528:Carcinoma, Hepatocellular / Q000175:diagnosis / Q000601:surgery*; D004598:Electrosurgery / Q000295:instrumentation*; D004867:Equipment Design; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007089:Image Enhancement; D008099:Liver / Q000473:pathology / Q000601:surgery; D008113:Liver Neoplasms / Q000175:diagnosis / Q000601:surgery*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome