title: False-Positive Tumor Enhancement After Cryoablation of Renal Cell Carcinoma: A Prospective Study.
abstract: OBJECTIVE
  The objective of the present study was to prospectively evaluate the frequency of false-positive tumor enhancement after cryoablation of renal cell carcinoma (RCC).
  
  
  METHODS
  Patients who underwent cryoablation of a single RCC smaller than 7 cm were enrolled in the study. Contrast-enhanced MRI examinations were performed at five time points (2-3 days, 5-7 days, 1 month, 3 months, and 6 months) after cryoablation. For patients with completely ablated RCCs, the frequency and patterns of false-positive tumor enhancement and the risk factors associated with such enhancement were evaluated at each time point.
  
  
  RESULTS
  The planned protocol was completed by 30 of the 33 enrolled patients (90.9%) with 30 RCCs (mean [± SD] size, 23.0 ± 8.7 cm; range, 1.0-4.7 cm). Complete tumor ablation was achieved for 25 RCCs (83.3%). Residual tumors were found in association with the other five RCCs (16.7%). Of the 25 completely ablated RCCs, false-positive tumor enhancement was observed for 15 tumors (60.0%) at 2-3 days after cryoablation; it continued to be observed for 13 tumors (52.0%) at 5-7 days and for one tumor (4.0%) at 1 month after cryoablation. The rate of false-positive tumor enhancement noted at 5-7 days after cryoablation was statistically significantly higher for clear cell RCCs (63.2%; 12/19) than for other RCC subtypes (16.7%; 1/6; p < 0.05).
  
  
  CONCLUSIONS
  False-positive tumor enhancement frequently continues to be observed, particularly in clear cell RCCs, until 1 month after cryoablation of RCCs.
authors.affiliation: 1 Department of Interventional Radiology, Mie University School of Medicine, 2-174 Edobashi, Tsu, Mie 514-8507, Japan.
authors.forename: Haruyuki
authors.initials: H
authors.lastname: Takaki
authors.affiliation: 1 Department of Interventional Radiology, Mie University School of Medicine, 2-174 Edobashi, Tsu, Mie 514-8507, Japan.
authors.forename: Atsuhiro
authors.initials: A
authors.lastname: Nakatsuka
authors.affiliation: 2 Department of Radiology, Bergonié Institute, Bordeaux, France.
authors.forename: Francois
authors.initials: F
authors.lastname: Cornelis
authors.affiliation: 1 Department of Interventional Radiology, Mie University School of Medicine, 2-174 Edobashi, Tsu, Mie 514-8507, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Yamanaka
authors.affiliation: 1 Department of Interventional Radiology, Mie University School of Medicine, 2-174 Edobashi, Tsu, Mie 514-8507, Japan.
authors.forename: Takaaki
authors.initials: T
authors.lastname: Hasegawa
authors.affiliation: 3 Department of Radiology, Mie University School of Medicine, Mie, Japan.
authors.forename: Hajime
authors.initials: H
authors.lastname: Sakuma
authors.affiliation: 1 Department of Interventional Radiology, Mie University School of Medicine, 2-174 Edobashi, Tsu, Mie 514-8507, Japan.
authors.forename: Koichiro
authors.initials: K
authors.lastname: Yamakado
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002292:Carcinoma, Renal Cell / Q000175:diagnosis* / Q000601:surgery; D003287:Contrast Media; D003452:Cryosurgery; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D007680:Kidney Neoplasms / Q000175:diagnosis* / Q000601:surgery; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012307:Risk Factors
chemical_list: D003287:Contrast Media
keywords: MRI; cryoablation; renal cell carcinoma