Observational Study
Copyright ©The Author(s) 2024. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Radiol. Jun 28, 2024; 16(6): 221-231
Published online Jun 28, 2024. doi: 10.4329/wjr.v16.i6.221
Renal resistive index measurements by ultrasound in patients with liver cirrhosis: Magnitude and associations with renal dysfunction
Himanshu Surya, Ramesh Kumar, Rajeev Nayan Priyadarshi, Sabbu Surya Prakash, Sudhir Kumar
Himanshu Surya, Ramesh Kumar, Sabbu Surya Prakash, Sudhir Kumar, Department of Gastroenterology, All India Institute of Medical Sciences, Patna 801507, India
Rajeev Nayan Priyadarshi, Department of Radiodiagnosis, All India Institute of Medical Sciences, Patna 801507, India
Author contributions: Himanshu S and Kumar R contributed to the concept and design of the manuscript, data collection, and manuscript writing; Priyadarshi RN, Surya Prakash S, and Kumar S contributed to the data collection, critical input, and manuscript writing; All authors have made a significant contribution and approved the final manuscript.
Institutional review board statement: The study was reviewed and approved by the Institute research board (Reference No: AIIMS/Pat/IEC/PGTh/July21/10).
Informed consent statement: All study participants, or their legal guardian, provided informed written consent prior to study enrolment.
Conflict-of-interest statement: The authors have no conflicts of interest to declare.
Data sharing statement: All relevant data included. No additional data are available.
STROBE statement: The authors have read the STROBE Statement checklist of items, and the manuscript was prepared and revised according to the STROBE Statement checklist of items.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: https://creativecommons.org/Licenses/by-nc/4.0/
Corresponding author: Ramesh Kumar, MBBS, MD, Additional Professor, Department of Gastroenterology, All India Institute of Medical Sciences, Phulwari Sharif, Patna 801507, India. docrameshkr@gmail.com
Received: March 7, 2024
Revised: May 17, 2024
Accepted: June 3, 2024
Published online: June 28, 2024
Processing time: 110 Days and 17.9 Hours
Abstract
BACKGROUND

The hemodynamic alterations seen in liver cirrhosis lead to renal vasoconstriction, ultimately causing acute kidney injury (AKI). The renal resistive index (RRI) is the most common Doppler ultrasound variable for measuring intrarenal vascular resistance.

AIM

To evaluate the association of the RRI with AKI in patients with liver cirrhosis and to identify risk factors for high RRI.

METHODS

This was a prospective observational study, where RRI was measured using Doppler ultrasound in 200 consecutive hospitalized patients with cirrhosis. The association of RRI with AKI was studied. The receiver operating characteristic (ROC) curve analysis was utilized to determine discriminatory cut-offs of RRI for various AKI phenotypes. Multivariate analysis was conducted to determine the predictors of high RRI.

RESULTS

The mean patient age was 49.08 ± 11.68 years, with the majority (79.5%) being male; the predominant etiology of cirrhosis was alcohol (39%). The mean RRI for the study cohort was 0.68 ± 0.09, showing a progressive increase with higher Child-Pugh class of cirrhosis. Overall, AKI was present in 129 (64.5%) patients. The mean RRI was significantly higher in patients with AKI compared to those without it (0.72 ± 0.06 vs 0.60 ± 0.08; P < 0.001). A total of 82 patients (41%) had hepatorenal syndrome (HRS)-AKI, 29 (22.4%) had prerenal AKI (PRA), and 18 (13.9%) had acute tubular necrosis (ATN)-AKI. The mean RRI was significantly higher in the ATN-AKI (0.80 ± 0.02) and HRS-AKI (0.73 ± 0.03) groups than in the PRA (0.63 ± 0.07) and non-AKI (0.60 ± 0.07) groups. RRI demonstrated excellent discriminatory ability in distinguishing ATN-AKI from non-ATN-AKI (area under ROC curve: 93.9%). AKI emerged as an independent predictor of high RRI (adjusted odds ratio [OR]: 11.52), and high RRI independently predicted mortality among AKI patients (adjusted OR: 3.18).

CONCLUSION

In cirrhosis patients, RRI exhibited a significant association with AKI, effectively differentiated between AKI phenotypes, and predicted AKI mortality.

Keywords: Renal resistive index, Cirrhosis, Acute kidney injury, Hepatorenal syndrome, Renal Doppler

Core Tip: Renal resistive index (RRI) is the most common Doppler ultrasound variable for measuring intrarenal vascular resistance. Higher RRI indicates renal vascular constriction in patients with advanced cirrhosis due to hemodynamic and neurohormonal alterations. This study evaluated the association of RRI with acute kidney injury (AKI) in patients with liver cirrhosis, assessed the diagnostic accuracy of RRI in distinguishing between different phenotypes of AKI, and identified predictors of high RRI. RRI correlated well with AKI, predicted its occurrence, differentiated between AKI phenotypes, and predicted mortality among AKI patients, and thus may be useful for evaluating renal dysfunction in cirrhosis patients.