title: VX2 carcinoma in rabbits after radiofrequency ablation: comparison of MR contrast agents for help in differentiating benign periablational enhancement from residual tumor.
abstract: OBJECTIVE
  To prospectively compare the accuracy of a blood pool agent, SH L 643A, with that of gadopentetate dimeglumine in differentiating benign periablational enhancement from residual tumor in VX2 carcinomas in rabbits after radiofrequency (RF) ablation.
  
  
  METHODS
  Experiment was approved by the animal care committee. Sequential MR images were obtained before and with SH L 643A (17 000 Da, 0.05 mmol/kg) and, after a 24-hour interval, gadopentetate dimeglumine (546 Da, 0.1 mmol/kg) in 12 rabbits with VX2 carcinoma in the back muscle prior to (n = 12) and early (n = 12), 1 week (n = 8), and 4 weeks (n = 4) after RF ablation. RF ablation was performed with output of 90 W but at less than 300 seconds to ensure incomplete tumor ablation. The pathologic specimens were sectioned in the same plane as MR imaging, and the enhancement ratios (ie, the ratios of postcontrast to precontrast signal intensity) and the microvessel densities of residual tumor and benign periablational enhancement were assessed.
  
  
  RESULTS
  With SH L 643A, the peak enhancement ratios of residual tumor (1.64 +/- 0.31 [standard deviation]) were significantly higher than those of benign periablational enhancement (0.97 +/- 0.16) (P < .001). With gadopentetate dimeglumine, the peak enhancement ratios of residual tumor (1.82 +/- 0.33) were not different from those of benign periablational enhancement (1.71 +/- 0.36). In benign periablational enhancement, enhancement ratios with injection of SH L 643A were lower than those with injection of gadopentetate dimeglumine for all time points up to 30 minutes (P < .05). The microvessel density was 25.72 +/- 5.43 vessels per field of view for residual tumor and 10.37 +/- 2.88 vessels per field of view for benign periablational enhancement (P < .001).
  
  
  CONCLUSIONS
  Blood pool contrast agent SH L 643A permits more accurate differentiation of benign periablational enhancement from residual tumor compared with the extracellular agent gadopentetate dimeglumine.
authors.affiliation: Department of Radiology and Clinical Research Institute, Seoul National University Hospital and the Institute of Radiation Medicine, Seoul National University Medical Research Center, 28 Yongon-dong, Chongno-gu, Seoul 110-744, Korea.
authors.forename: Tae Jung
authors.initials: TJ
authors.lastname: Kim
authors.forename: Woo Kyung
authors.initials: WK
authors.lastname: Moon
authors.forename: Joo Hee
authors.initials: JH
authors.lastname: Cha
authors.forename: Jin Mo
authors.initials: JM
authors.lastname: Goo
authors.forename: Kyoung Ho
authors.initials: KH
authors.lastname: Lee
authors.forename: Keon Ha
authors.initials: KH
authors.lastname: Kim
authors.forename: Joon Woo
authors.initials: JW
authors.lastname: Lee
authors.forename: Joon Goo
authors.initials: JG
authors.lastname: Han
authors.forename: Hanns-Joachim
authors.initials: HJ
authors.lastname: Weinmann
authors.forename: Kee Hyun
authors.initials: KH
authors.lastname: Chang
mesh_terms: D000818:Animals; D017115:Catheter Ablation; D003287:Contrast Media; D003937:Diagnosis, Differential; D005682:Gadolinium; D019786:Gadolinium DTPA; D008279:Magnetic Resonance Imaging; D018365:Neoplasm, Residual / Q000175:diagnosis*; D009374:Neoplasms, Experimental / Q000175:diagnosis / Q000601:surgery*; D011446:Prospective Studies; D011817:Rabbits
chemical_list: D003287:Contrast Media; C402765:gadomer 17; D005682:Gadolinium; D019786:Gadolinium DTPA