title: Four-dimensional transcatheter intraarterial perfusion MRI monitoring of radiofrequency ablation of rabbit VX2 liver tumors.
abstract: OBJECTIVE
  To investigate the hypothesis that four-dimensional (4D) transcatheter intraarterial perfusion (TRIP) magnetic resonance imaging (MRI) can quantify immediate perfusion changes after radiofrequency (RF) ablation in rabbit VX2 liver tumors.
  
  
  METHODS
  Nine New Zealand White rabbits were used to surgically implant VX2 liver tumors. During ultrasound-guided RF ablation, tumors received either a true or sham ablation. After selective catheterization of the left hepatic artery under x-ray fluoroscopy, we acquired pre- and post-RF ablation 4D TRIP MR images using 3 mL of 2.5% intraarterial gadopentetate dimeglumine. Two regions-of-interest were drawn upon each tumor to generate signal-intensity time curves. Area under the curve (AUC) was calculated to provide semiquantitative perfusion measurements that were compared using a paired t-test (α = 0.05). Ablated tissue was visually confirmed on pathology using Evans blue dye.
  
  
  RESULTS
  Mean AUC perfusion of VX2 tumors for the true ablation group decreased by 92.0% (95% confidence interval [CI]: 83.3%-100%), from 1913 (95% CI: 1557, 2269) before RF ablation to 76.6 (95% CI: 18.4, 134.8) after RF ablation (a.u., P < 0.001). Sham-ablated tumors demonstrated no significant perfusion changes.
  
  
  CONCLUSIONS
  4D TRIP MRI can quantify liver tumor perfusion reductions in VX2 rabbits after RF ablation. This MRI technique can potentially be used to improve tumor response assessment at the time of RF ablation.
authors.affiliation: Department of Radiology, Northwestern University, Chicago, Illinois, USA.
authors.forename: Kent T
authors.initials: KT
authors.lastname: Sato
authors.forename: Dingxin
authors.initials: D
authors.lastname: Wang
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Lewandowski
authors.forename: Robert K
authors.initials: RK
authors.lastname: Ryu
authors.forename: Rachel A
authors.initials: RA
authors.lastname: Klein
authors.forename: Riad
authors.initials: R
authors.lastname: Salem
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Larson
authors.forename: Reed A
authors.initials: RA
authors.lastname: Omary
mesh_terms: D000465:Algorithms; D000818:Animals; D045744:Cell Line, Tumor; D005260:Female; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008113:Liver Neoplasms / Q000473:pathology* / Q000601:surgery*; D018810:Magnetic Resonance Angiography / Q000379:methods*; D011817:Rabbits; D015203:Reproducibility of Results; D055425:Respiratory-Gated Imaging Techniques / Q000379:methods*; D012680:Sensitivity and Specificity; D025321:Surgery, Computer-Assisted / Q000379:methods*; D016896:Treatment Outcome