title: MRI-based kidney volume measurements in ADPKD: reliability and effect of gadolinium enhancement.
abstract: OBJECTIVE
  To evaluate the inter- and intrareader reliability and the effect of gadolinium enhancement on kidney volume measurements obtained from pre- and postgadolinium T1 MR images in patients with autosomal dominant polycystic kidney disease (ADPKD).
  
  
  METHODS
  Twenty subjects were randomly selected with approximately equal frequency from three kidney-size groups. Pre- and postgadolinium 3D T1 (pre-T1, post-T1) MR images were obtained. The stereology method was applied to segment and measure kidney volumes. The measurement process was repeated at two-wk intervals by two radiologists. Reliability was assessed with correlation coefficients. Intra- and inter-reader bias and measure differences were assessed with paired T-tests. The size effect on the pre- and post-T1 measurements was evaluated with one-way ANOVA.
  
  
  RESULTS
  The intra- and inter-reader reliability was extremely high in all measurements. No systematic intrareader bias but a small inter-reader bias for the post-T1 measurements was observed. All kidney volumes measured on the pre- and post-T1 images were highly correlated with each other for both readers. The post-T1 volumes were significantly higher than pre-T1 volumes. While the post-pre volume differences were relatively constant across the three kidney-size groups, the post-pre percent volume differences were significantly smaller as the size of the kidney increased.
  
  
  CONCLUSIONS
  Kidney volume measurements can be made with minimum intra- and inter-reader variability on both pre- and post-T1 MR images. Kidney volumes measured on the pre-T1 were smaller than those on post-T1, and percent differences between pre-T1 and post-T1 kidney volumes decreased with increasing kidney size.
authors.affiliation: Department of Radiology, University of Pittsburgh, Pennsylvania 15213, USA. baek@upmc.edu
authors.forename: Kyongtae T
authors.initials: KT
authors.lastname: Bae
authors.forename: Cheng
authors.initials: C
authors.lastname: Tao
authors.forename: Fang
authors.initials: F
authors.lastname: Zhu
authors.forename: James E
authors.initials: JE
authors.lastname: Bost
authors.forename: Arlene B
authors.initials: AB
authors.lastname: Chapman
authors.forename: Jared J
authors.initials: JJ
authors.lastname: Grantham
authors.forename: Vicente E
authors.initials: VE
authors.lastname: Torres
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Guay-Woodford
authors.forename: Catherine M
authors.initials: CM
authors.lastname: Meyers
authors.forename: William M
authors.initials: WM
authors.lastname: Bennett