Abstract
Objective
Low-energy shockwave (SW) therapy attenuates damage in the stenotic kidney (STK) caused by atherosclerotic renal artery stenosis (ARAS). We hypothesized that magnetic resonance elastography (MRE) would detect attenuation of fibrosis following SW in unilateral ARAS kidneys.
Materials and methods
Domestic pigs were randomized to control, unilateral ARAS, and ARAS treated with 6 sessions of SW over 3 consecutive weeks (n = 7 each) starting after 3 weeks of ARAS or sham. Four weeks after SW treatment, renal fibrosis was evaluated with MRE in vivo or trichrome staining ex vivo. Blood pressure, single-kidney renal-blood-flow (RBF) and glomerular-filtration-rate (GFR) were assessed.
Results
MRE detected increased stiffness in the STK medulla (15.3 ± 2.1 vs. 10.1 ± 0.8 kPa, p < 0.05) that moderately correlated with severity of fibrosis (R2 = 0.501, p < 0.01), but did not identify mild STK cortical or contralateral kidney fibrosis. Trichrome staining showed that medullary fibrosis was increased in ARAS and alleviated by SW (10.4 ± 1.8% vs. 2.9 ± 0.2%, p < 0.01). SW slightly decreased blood pressure and normalized STK RBF and GFR in ARAS. In the contralateral kidney, SW reversed the increase in RBF and GFR.
Conclusion
MRE might be a tool for noninvasive monitoring of medullary fibrosis in response to treatment in kidney disease.
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Abbreviations
- SW:
-
Shockwave
- MRI:
-
Magnetic resonance imaging
- MRE:
-
Magnetic resonance elastography
- DWI:
-
Diffusion-weighted imaging
- EPI:
-
Echo-planar imaging
- MEG:
-
Motion encoding gradients
- ROI:
-
Region of interest
- MDCT:
-
Multi-detector computed tomography
- ARAS:
-
Atherosclerotic renal artery stenosis
- STK:
-
Stenotic kidney
- CLK:
-
Contralateral kidney
- RBF:
-
Renal blood flow
- GFR:
-
Glomerular filtration rate
- MAP:
-
Mean arterial pressure
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Acknowledgements
This study was partly supported by NIH grants numbers HL123160, DK73608, DK104273, HL121561, C06-RR018898. We are grateful to Medispec® LTD, Gaithersburg, MD, for generously allowing the use of the SW machine. The machine sponsor was not involved in data collection or analysis.
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ZX Protocol, data collection, data analysis; ZX Data collection; FC Data collection/data analysis; JK Data analysis; BT Data analysis; LA Protocol; LLO Protocol/project development
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All applicable international, national, and/or institutional guidelines for care and use of animals were followed. All procedures performed in studies involving animals were in accordance with the ethical standards of the institution or practice at which the studies were conducted. This article does not contain any studies with human participants performed by any of the authors.
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10334_2017_671_MOESM1_ESM.tiff
Top: Representative images and quantification of trichrome staining from contralateral medulla. SW ameliorated the increased medullary fibrosis in ARAS CLK. Bottom: Representative MRE images (yellow/red color indicates greater stiffness) from contralateral cortex and medulla (TIFF 2309 kb)
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Zhang, X., Zhu, X., Ferguson, C.M. et al. Magnetic resonance elastography can monitor changes in medullary stiffness in response to treatment in the swine ischemic kidney. Magn Reson Mater Phy 31, 375–382 (2018). https://doi.org/10.1007/s10334-017-0671-7
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DOI: https://doi.org/10.1007/s10334-017-0671-7