title: Kidney volume estimations with ellipsoid equations by magnetic resonance imaging in autosomal dominant polycystic kidney disease.
abstract: BACKGROUND
  Kidney volume (KV) becomes clinically relevant in autosomal dominant polycystic kidney disease (ADPKD) management. KV can be conveniently estimated (ceKV) using ellipsoid volume equations with three axes measurements; however, the accuracy and reliability are unknown.
  
  
  METHODS
  KVs of 347 kidneys in 177 consecutive ADPKD patients were determined with a volumetric method (standard-KV), and ceKV was calculated using six different ellipsoid equations with three axes measurements using magnetic resonance imaging. The inter- and intraobserver reliabilities were analyzed using intraclass correlation coefficients (ICCs). Ellipsoid-KVs were obtained by linear regression analysis between standard-KV and ceKVs, and six ellipsoid-KVs were validated with a bootstrap model.
  
  
  RESULTS
  The ICCs of intra- and interobserver reliabilities in standard-KV and axes measurements were highly reliable. All ceKVs underestimated standard-KV and % differences between ceKV and standard-KV were reduced by ellipsoid-KVs. Bootstrap analyses suggested that six ellipsoid-KVs reliably simulated standard-KV.
  
  
  CONCLUSIONS
  Among six ellipsoid-KVs, ellipsoid-KV3 = 84 + 1.01 x π/24 × Length × (sum of two width measurements)(2) relatively accurately simulated the standard-KV. Kidney volume estimation using ellipsoid equations is reliably applied to clinical management of ADPKD while recognizing wide scattering in the difference between estimated and volumetrically measured kidney volume.
authors.affiliation: Department of ADPKD Research, Kyorin University School of Medicine, Tokyo, Japan.
authors.forename: Eiji
authors.initials: E
authors.lastname: Higashihara
authors.forename: Kikuo
authors.initials: K
authors.lastname: Nutahara
authors.forename: Takatsugu
authors.initials: T
authors.lastname: Okegawa
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Tanbo
authors.forename: Hidehiko
authors.initials: H
authors.lastname: Hara
authors.forename: Isao
authors.initials: I
authors.lastname: Miyazaki
authors.forename: Kuninori
authors.initials: K
authors.lastname: Kobayasi
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Nitatori
mesh_terms: D000328:Adult; D000368:Aged; D000465:Algorithms; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D007668:Kidney / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods* / Q000706:statistics & numerical data; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D019047:Phantoms, Imaging; D016891:Polycystic Kidney, Autosomal Dominant / Q000473:pathology*; D012044:Regression Analysis; D015203:Reproducibility of Results