Measuring rat kidney glomerular number and size in vivo with MRI

Edwin J. Baldelomar, Jennifer R. Charlton, Scott C. Beeman, Kevin M. Bennett

Research output: Contribution to journalArticlepeer-review

13 Scopus citations

Abstract

Nephron number is highly variable in humans and is thought to play an important role in renal health. Chronic kidney disease (CKD) is the result of too few nephrons to maintain homeostasis. Currently, nephron number can only be determined invasively or as a terminal assessment. Due to a lack of tools to measure and track nephron number in the living, the early stages of CKD often go unrecognized, preventing early intervention that might halt the progression of CKD. In this work, we present a technique to directly measure glomerular number (N glom ) and volume in vivo in the rat kidney (n + 8) using MRI enhanced with the novel contrast agent cationized ferritin (CFE-MRI). Adult male rats were administered intravenous cationized ferritin (CF) and imaged in vivo with MRI. Glomerular number was measured and each glomerulus was spatially mapped in 3D in the image. Mean apparent glomerular volume (aV glom ) and intrarenal distribution of the individual glomerular volume (IGV), were also measured. These metrics were compared between images of the same kidneys scanned in vivo and ex vivo with CFE-MRI. In vivo N glom and aV glom correlated to ex vivo metrics within the same kidneys and were within 10% of N glom and aV glom previously validated by stereologic methods. This is the first report of direct in vivo measurements of N glom and aV glom , introducing an opportunity to investigate mechanisms of renal disease progression and therapeutic response over time.

Original languageEnglish (US)
Pages (from-to)F399-F406
JournalAmerican Journal of Physiology - Renal Physiology
Volume314
Issue number3
DOIs
StatePublished - Mar 2018

Keywords

  • CFE-MRI
  • Glomerular volume
  • In vivo
  • Magnetic resonance imaging (MRI)
  • N
  • Nephron number
  • V

ASJC Scopus subject areas

  • Physiology
  • Urology

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