Association of Contrast-Enhanced Ultrasound-Derived Kidney Cortical Microvascular Perfusion with Kidney Function.

Background: Individuals with chronic kidney disease (CKD) have decreased kidney cortical microvascular perfusion, which may lead to worsening kidney function over time, but methods to quantify kidney cortical microvascular perfusion are not feasible to incorporate into clinical practice. Contrast-enhanced ultrasound (CEUS) may quantify kidney cortical microvascular perfusion, which requires further investigation in individuals across the spectrum of kidney function.
Methods: We performed CEUS on a native kidney of 83 individuals across the spectrum of kidney function and calculated quantitative CEUS-derived kidney cortical microvascular perfusion biomarkers. Participants had a continuous infusion of the microbubble contrast agent (Definity) with a flash-replenishment sequence during their CEUS scan. Lower values of the microbubble velocity ( β ) and perfusion index ( β ×A) may represent lower kidney cortical microvascular perfusion. Multivariable linear regression models tested the associations of the microbubble velocity ( β ) and perfusion index ( β ×A) with estimated glomerular filtration rate (eGFR).
Results: Thirty-eight individuals with CKD (mean age±SD 65.2±12.6 years, median [IQR] eGFR 31.5 [18.9-41.5] ml/min per 1.73 m ² ), 37 individuals with end stage kidney disease (ESKD; age 54.8±12.3 years), and eight healthy volunteers (age 44.1±15.0 years, eGFR 117 [106-120] ml/min per 1.73 m ² ) underwent CEUS without side effects. Individuals with ESKD had the lowest microbubble velocity ( β ) and perfusion index ( β ×A) compared with individuals with CKD and healthy volunteers. The microbubble velocity ( β ) and perfusion index ( β ×A) had moderate positive correlations with eGFR ( β : r _s =0.44, P <0.001; β ×A: r _s =0.50, P <0.001). After multivariable adjustment, microbubble velocity ( β ) and perfusion index ( β ×A) remained significantly associated with eGFR (change in natural log transformed eGFR per 1 unit increase in natural log transformed biomarker: β , 0.38 [95%, CI 0.17 to 0.59]; β ×A, 0.79 [95% CI, 0.45 to 1.13]).
Conclusions: CEUS-derived kidney cortical microvascular perfusion biomarkers are associated with eGFR. Future studies are needed to determine if CEUS-derived kidney cortical microvascular perfusion biomarkers have prognostic value.
Competing Interests: E.H. Chang reports research funding from Lantheus Medical Imaging and is on the medical advisory board for the North Carolina chapter of the National Kidney Foundation. P. Dayton reports consultancy for SonoVascular, Inc., SonoVol, Inc., and Triangle Biotechnology, Inc.; ownership interest in SonoVascular, Inc., SonoVol, Inc., and Triangle Biotechnology, Inc.; research funding from Kitware, LLC, SonoVol, Inc., and Triangle Biotechnology, Inc.; patents or royalties from SonoVascular, Inc., SonoVol, Inc., and Triangle Biotechnology, Inc.; an advisory or leadership role for SonoVascular, Inc., SonoVol, LLC, and Triangle Biotechnology, Inc.; and other interests or relationships with Pfizer, Inc. R. Walmer reports consultancy agreements with SonoVol, Inc. (entered into on November 2, 2021). A. Srivastava reports consultancy agreements with CVS Caremark and Tate & Latham (medicolegal consulting); honoraria from AstraZeneca, Bayer, and Horizon Therapeutics plc.; and participation in a speakers’ bureau for AstraZeneca. All remaining authors have nothing to disclose.
(Copyright © 2022 by the American Society of Nephrology.)