title: Live nephron imaging by MRI.
abstract: The local sensitivity of MRI can be improved with small MR detectors placed close to regions of interest. However, to maintain such sensitivity advantage, local detectors normally need to communicate with the external amplifier through cable connections, which prevent the use of local detectors as implantable devices. Recently, an integrated wireless amplifier was developed that can efficiently amplify and broadcast locally detected signals, so that the local sensitivity was enhanced without the need for cable connections. This integrated detector enabled the live imaging of individual glomeruli using negative contrast introduced by cationized ferritin, and the live imaging of renal tubules using positive contrast introduced by gadopentetate dimeglumine. Here, we utilized the high blood flow to image individual glomeruli as hyperintense regions without any contrast agent. These hyperintense regions were identified for pixels with signal intensities higher than the local average. Addition of Mn(2+) allowed the simultaneous detection of both glomeruli and renal tubules: Mn(2+) was primarily reabsorbed by renal tubules, which would be distinguished from glomeruli due to higher enhancement in T1-weighted MRI. Dynamic studies of Mn(2+) absorption confirmed the differential absorption affinity of glomeruli and renal tubules, potentially enabling the in vivo observation of nephron function.
authors.affiliation: Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorder and Stroke, National Institutes of Health, Bethesda, Maryland; qianc2@ninds.nih.gov.
authors.forename: Chunqi
authors.initials: C
authors.lastname: Qian
authors.affiliation: Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorder and Stroke, National Institutes of Health, Bethesda, Maryland; High-Field Magnetic Resonance Department, Max Planck Institute for Biological Cybernetics, Tubingen, Germany.
authors.forename: Xin
authors.initials: X
authors.lastname: Yu
authors.affiliation: Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorder and Stroke, National Institutes of Health, Bethesda, Maryland;
authors.forename: Nikorn
authors.initials: N
authors.lastname: Pothayee
authors.affiliation: Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorder and Stroke, National Institutes of Health, Bethesda, Maryland;
authors.forename: Stephen
authors.initials: S
authors.lastname: Dodd
authors.affiliation: Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorder and Stroke, National Institutes of Health, Bethesda, Maryland;
authors.forename: Nadia
authors.initials: N
authors.lastname: Bouraoud
authors.affiliation: Division of Kidney Urologic and Hematologic Diseases, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland;
authors.forename: Robert
authors.initials: R
authors.lastname: Star
authors.affiliation: Department of Biology, University of Hawaii, Honolulu, Hawaii; and.
authors.forename: Kevin
authors.initials: K
authors.lastname: Bennett
authors.affiliation: Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorder and Stroke, National Institutes of Health, Bethesda, Maryland;
authors.forename: Alan
authors.initials: A
authors.lastname: Koretsky
mesh_terms: D000818:Animals; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods*; D008297:Male; D009399:Nephrons / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley
keywords: MRI; filtration; glomeruli; perfusion; renal tubules