title: Measurement of renal volumes with contrast-enhanced MRI.
abstract: OBJECTIVE
  To determine the accuracy of in vivo magnetic resonance imaging (MRI) measurement of total renal parenchymal volume and medullary fraction.
  
  
  METHODS
  Sixteen kidneys in eight pigs were imaged with a multiphasic contrast-enhanced fast three-dimensional sequence on a 1.5-T imager. Kidney segmentation, followed by a process of signal intensity thresholding for cortical and nephrographic phase datasets, allowed for MRI measurements of parenchymal volume and medullary fraction. Autopsy provided reference standards of renal volume, weight, and medullary fraction.
  
  
  RESULTS
  An excellent correlation was found between MRI measurement of total renal parenchymal volume and autopsy volume (R2 = 0.86) and weight (R2 = 0.90). Medullary fraction (mean +/- SD) measured with MRI was 0.120 +/- 0.067, and with autopsy was 0.116 +/- 0.025 (t-test P = 0.84, F-test P = 0.001).
  
  
  CONCLUSIONS
  MRI measurements of total renal volume are accurate. MRI measurements of medullary fraction show promise, but precision is limited when using a simple signal intensity thresholding algorithm.
authors.affiliation: Department of Radiology, Stanford University School of Medicine, Stanford, California 94205, USA.
authors.forename: Curtis H
authors.initials: CH
authors.lastname: Coulam
authors.forename: Donna M
authors.initials: DM
authors.lastname: Bouley
authors.forename: F Graham
authors.initials: FG
authors.lastname: Sommer
mesh_terms: D000818:Animals; D001344:Autopsy; D003287:Contrast Media; D019786:Gadolinium DTPA; D007668:Kidney / Q000098:blood supply / Q000473:pathology*; D007672:Kidney Cortex / Q000473:pathology; D007679:Kidney Medulla / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000379:methods*; D023421:Models, Animal; D012078:Renal Artery Obstruction / Q000175:diagnosis*; D012079:Renal Circulation; D013552:Swine
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA