title: Noninvasive evaluation of kidney hypoxia and fibrosis using magnetic resonance imaging.
abstract: Interstitial fibrosis and hypoxia accelerate the progression of CKD, but clinical tools to quantitate these factors in patients are lacking. Here, we evaluated the use of two magnetic resonance imaging (MRI) techniques, diffusion-weighted (DW)-MRI and blood oxygen level-dependent (BOLD)-MRI, to assess kidney fibrosis and hypoxia of the cortex in 142 patients with either diabetic nephropathy (n = 43), CKD without diabetes (n = 76), or acute kidney injury (AKI) (n = 23). Apparent diffusion coefficient (ADC) values of DW-MRI correlated with estimated glomerular filtration rates (eGFR) in the diabetic nephropathy and CKD groups (r(2) = 0.56 and r(2) = 0.46, respectively). Although the T2* values of BOLD-MRI and eGFR displayed good correlation in the CKD group (r(2) = 0.38), we did not observe a significant correlation between these values in the diabetic nephropathy group, suggesting that factors other than tubulointerstitial alteration determine the degree of hypoxia in the renal cortex. In the AKI group, neither the T2* nor ADC values correlated with eGFR. Renal biopsies from patients with CKD demonstrated that the T2* and ADC MRI values correlated with renal pathology. Taken together, ADC and T2* values appear to serve as accurate indices for evaluating renal tubulointerstitial alterations and parenchymal hypoxia, respectively, in the cortex. Functional MRI can thus contribute to multilateral, noninvasive, in vivo assessment of kidney function.
authors.affiliation: Department of Nephrology, Faculty of Medicine, Saitama Medical University, Saitama, Japan.
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Inoue
authors.forename: Eito
authors.initials: E
authors.lastname: Kozawa
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Okada
authors.forename: Kouichi
authors.initials: K
authors.lastname: Inukai
authors.forename: Shinichi
authors.initials: S
authors.lastname: Watanabe
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Kikuta
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Watanabe
authors.forename: Tsuneo
authors.initials: T
authors.lastname: Takenaka
authors.forename: Shigehiro
authors.initials: S
authors.lastname: Katayama
authors.forename: Junji
authors.initials: J
authors.lastname: Tanaka
authors.forename: Hiromichi
authors.initials: H
authors.lastname: Suzuki
mesh_terms: D000328:Adult; D001706:Biopsy; D003928:Diabetic Nephropathies / Q000473:pathology; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods; D005260:Female; D005355:Fibrosis / Q000175:diagnosis / Q000473:pathology*; D005919:Glomerular Filtration Rate; D006801:Humans; D000860:Hypoxia / Q000175:diagnosis / Q000473:pathology*; D007668:Kidney / Q000473:pathology*; D007676:Kidney Failure, Chronic / Q000175:diagnosis / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D010100:Oxygen / Q000378:metabolism; D011877:Radionuclide Imaging / Q000379:methods
chemical_list: D010100:Oxygen