title: Magnetic resonance imaging after radiofrequency ablation in a rodent model of liver tumor: tissue characterization using a novel necrosis-avid contrast agent.
abstract: We exploited a necrosis-avid contrast agent ECIV-7 for magnetic resonance imaging (MRI) in rodent liver tumors after radiofrequency ablation (RFA). Rats bearing liver rhabdomyosarcoma (R1) were randomly allocated to three groups: group I, complete RFA, group II, incomplete RFA, and group III, sham ablation. Within 24 h after RFA, T1-weighted (T1-w) MRI was performed before and after injection of ECIV-7 at 0.05 mmol/kg and followed up from 6-24 h. Signal intensities (SIs) were measured with relative enhancement (RE) and contrast ratio (CR) calculated. The MRI findings were verified histomorphologically. On plain T1-w MRI the contrasts between normal liver, RFA lesion, residual and/or intact tumor were vague. Early after administration of ECIV-7, the liver SI was strongly enhanced (RE=40-50%), leaving the RFA lesion as a hypointense region in groups I and II. At delayed phase, two striking peri-ablational enhancement patterns appeared (RE=90% and CR=1.89%), i.e., "O" type of hyperintense rim in group I and "C" type of incomplete rim in group II. These MRI manifestations could be proven histologically. In this study, tissue components after RFA could be characterized with discernable contrasts by necrosis-avid contrast agent (NACA)-enhanced MRI, especially at delayed phase. This approach may prove useful for defining the ablated area and identifying residual tumor after RFA.
authors.affiliation: Department of Radiology, University Hospitals, Catholic University of Leuven, Herestraat 49, 3000 Leuven, Belgium. Yicheng.Ni@med.kuleuven.ac.be
authors.forename: Yicheng
authors.initials: Y
authors.lastname: Ni
authors.forename: Feng
authors.initials: F
authors.lastname: Chen
authors.forename: Stefaan
authors.initials: S
authors.lastname: Mulier
authors.forename: Xihe
authors.initials: X
authors.lastname: Sun
authors.forename: Jie
authors.initials: J
authors.lastname: Yu
authors.forename: Willy
authors.initials: W
authors.lastname: Landuyt
authors.forename: Guy
authors.initials: G
authors.lastname: Marchal
authors.forename: Alfons
authors.initials: A
authors.lastname: Verbruggen
mesh_terms: D000818:Animals; D017115:Catheter Ablation; D003287:Contrast Media / Q000008:administration & dosage*; D019786:Gadolinium DTPA / Q000008:administration & dosage; D007089:Image Enhancement; D008114:Liver Neoplasms, Experimental / Q000473:pathology* / Q000601:surgery*; D008279:Magnetic Resonance Imaging; D008297:Male; D009336:Necrosis / Q000473:pathology / Q000601:surgery; D011182:Postoperative Care; D051381:Rats; D013997:Time Factors
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA