The aim of this study was to noninvasively evaluate changes in renal stiffness, diffusion, and oxygenation in patients with chronic, advanced stage immunoglobulin A nephropathy (IgAN) by multiparametric magnetic resonance imaging using tomoelastography, diffusion-weighted imaging (DWI), and blood oxygen level–dependent (BOLD) imaging.
In this prospective study, 32 subjects (16 patients with biopsy-proven IgAN and 16 age- and sex-matched healthy controls) underwent multifrequency magnetic resonance elastography with tomoelastography postprocessing at 4 frequencies from 40 to 70 Hz to generate shear wave speed (meter per second) maps reflecting tissue stiffness. In addition, DWI and BOLD imaging were performed to determine the apparent diffusion coefficient in square millimeter per second and T2* relaxation time in milliseconds, respectively. Regions including the entire renal parenchyma of both kidneys were analyzed. Areas under the receiver operating characteristic (AUCs) curve were calculated to test diagnostic performance. Clinical parameters such as estimated glomerular filtration rate and protein-to-creatinine ratio were determined and correlated with imaging findings.
Success rates of tomoelastography, DWI, and BOLD imaging regarding both kidneys were 100%, 91%, and 87%, respectively. Shear wave speed was decreased in IgAN (−21%, P < 0.0001), accompanied by lower apparent diffusion coefficient values (−12%, P = 0.004). BOLD imaging was not sensitive to IgAN (P = 0.12). Tomoelastography detected IgAN with higher diagnostic accuracy than DWI (area under the curve = 0.9 vs 0.8) and positively correlated with estimated glomerular filtration rate (r = 0.66, P = 0.006).
Chronic, advanced stage IgAN is associated with renal softening and restricted water diffusion. Tomoelastography is superior to DWI and BOLD imaging in detecting IgAN.
From the Departments of *Radiology
§Institute of Medical Informatics, Charité – Universitätsmedizin Berlin, coporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.
Received for publication February 16, 2019; and accepted for publication, after revision, April 25, 2019.
Conflict of interest and sources of funding: This study was supported by the German Federal Ministry of Education and Research (LiSyM 031 L0057 to I.S.) and the German Research Foundation (DFG GU 1726/1-1 to J.G., BIOQIC GRK 2260 to I.S., SFB 1340 to B.H., I.S., J.B., and J.G.).
Correspondence to: Stephan Rodrigo Marticorena Garcia, MD, Department of Radiology, Charité – Universitätsmedizin Berlin, coporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Charitéplatz 1, 10117 Berlin, Germany. E-mail: firstname.lastname@example.org.
Online date: July 1, 2019