Measuring rat kidney glomerular number and size in vivo with MRI.
Authors Baldelomar EJ, Charlton JR, Beeman SC, Bennett KM
Submitted By Kevin Bennett on 2/19/2018
Status Published
Journal American journal of physiology. Renal physiology
Year 2017
Date Published 11/1/2017
Volume : Pages Not Specified : ajprenal00
PubMed Reference 29092847
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 estimates 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
(Nglom) 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 (aVglom) and intra-renal 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 Nglomand aVglomcorrelated to ex vivo metrics within the same
kidneys and were within 10% of Nglomand aVglompreviously validated by
stereologic methods. This is the first description of direct in vivo
measurements of Nglomand aVglom, introducing an opportunity to investigate
mechanisms of renal disease progression and therapeutic response over time.