title: Functional CT quantification of tumor perfusion after transhepatic arterial embolization in a rat model.
abstract: OBJECTIVE
  To quantify tumor perfusion after transcatheter arterial embolization (TAE) with functional computed tomography (CT) and to validate the reproducibility of quantification measurements.
  
  
  METHODS
  This study was conducted in accordance with an institutional animal care and use committee-approved protocol. Sixteen rats with liver tumors underwent TAE with 1 mg (group 1) or 3 mg (group 2) of polyvinyl alcohol particles. In each group, four rats underwent functional CT immediately after TAE (day 0) and four others underwent functional CT 2 days after TAE (day 2). Another four rats served as control rats. Blood flow (BF), blood volume (BV), mean transit time (MTT), and permeability-surface area product were measured by using a functional CT software program. For evaluation of reproducibility, six additional rats with mammary tumors underwent functional CT twice, with examinations 2 hours apart. The mixed-effect model was used to assess the TAE treatment effect, and the Pearson correlation test was used to determine measurement reproducibility.
  
  
  RESULTS
  With the exception of BF in group 1 on day 2 (P = .41), BF and BV values in both groups on both days were significantly lower than BF and BV values in the control rats (with P values ranging from .018 to <.001). BF was significantly lower in group 2 than in group 1 on days 0 and 2 (P = .043 and P = .02, respectively). BV was significantly lower on day 2 than on day 0 in group 2 (P = .016). MTT was generally inversely related to BF. MTTs in group 2 on days 0 and 2 were significantly longer than those in the control rats (P < .001 and P = .03, respectively), and MTT was shorter on day 2 than on day 0 in group 2 (P = .02). Permeability-surface area product changes were similar to BF changes. There were no significant differences (P values ranged from .2 to .5) between perfusion parameters in the reproducibility study.
  
  
  CONCLUSIONS
  The results of this study validate the use of functional CT in the quantification of tumor perfusion after TAE and the reproducibility of such quantification measurements.
authors.affiliation: Division of Diagnostic Imaging, Department of Diagnostic Radiology, University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Blvd, Unit 57, Houston, TX 77030, USA. zkan@di.mdacc.tmc.edu
authors.forename: Zuxing
authors.initials: Z
authors.lastname: Kan
authors.forename: Satoshi
authors.initials: S
authors.lastname: Kobayashi
authors.forename: Sith
authors.initials: S
authors.lastname: Phongkitkarun
authors.forename: Chusilp
authors.initials: C
authors.lastname: Charnsangavej
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D004621:Embolization, Therapeutic / Q000379:methods*; D005260:Female; D008114:Liver Neoplasms, Experimental / Q000098:blood supply* / Q000000981:diagnostic imaging* / Q000628:therapy; D051381:Rats; D011916:Rats, Inbred F344; D015203:Reproducibility of Results; D014057:Tomography, X-Ray Computed / Q000379:methods*