title: Computed tomographic appearance of lung tumors treated with percutaneous cryoablation.
abstract: OBJECTIVE
  To describe the computed tomographic (CT) appearance of lung tumors treated with cryoablation to establish a reliable reference profile.
  
  
  METHODS
  CT images of 56 patients who underwent follow-up CT for at least 1 year for treatment with cryoablation of 79 tumors from 2003 to 2010 were retrospectively reviewed. Patients had a follow-up CT scan immediately after the procedure; 1 day, 1 week (two-phase dynamic CT), and 1 month later; and then at 3-month intervals. The appearance of ablation zones on CT images was classified into five patterns, and bidimensional diameters and other imaging features were evaluated.
  
  
  RESULTS
  Seventy-eight percent of ablation zones (62 of 79) showed transformation similar to the following: a consolidation or nodular pattern was seen within the 1-week follow-up, involution and a "stripe" pattern was shown at 1 month or later, and zones later became indistinct. Eighty percent of cases of local progression (eight of 10) arose from the stripe pattern on follow-up CT 6 months or later, after the ablation zones showed a transformation opposite the aforementioned pattern. Ice balls could not always be visualized exactly because of dense peritumoral hemorrhage. Internal and marginal enhancement of the ablation zone within the 3-month follow-up did not show a direct relationship with local progression. In total, cavitation and peritumoral ground-glass opacity were seen in 35% (n = 28) and 85% (n = 66) of ablation zones, respectively.
  
  
  CONCLUSIONS
  The reference profile of CT appearance, which is mandatory for follow-up, has been established. No single indicator of complete ablation was proven throughout this study. Careful long-term follow-up with CT is indispensable.
authors: Department of Diagnostic Radiology, Keio University School of Medicine, 35 Shinanomachi,Shinjuku-ku, Tokyo, Japan. nobutake@rad.med.keio.ac.jp
authors: Nobutake
authors: N
authors: Ito
authors: Seishi
authors: S
authors: Nakatsuka
authors: Masanori
authors: M
authors: Inoue
authors: Hideki
authors: H
authors: Yashiro
authors: Sota
authors: S
authors: Oguro
authors: Yotaro
authors: Y
authors: Izumi
authors: Masafumi
authors: M
authors: Kawamura
authors: Hiroaki
authors: H
authors: Nomori
authors: Sachio
authors: S
authors: Kuribayashi
mesh_terms: D003452:Cryosurgery / Q000592:standards; D006801:Humans; D007564:Japan; D008175:Lung Neoplasms / Q000000981:diagnostic imaging* / Q000601:surgery*; D061330:Multidetector Computed Tomography / Q000592:standards; D011237:Predictive Value of Tests; D012016:Reference Values; D012189:Retrospective Studies; D013997:Time Factors; D016896:Treatment Outcome