# A Study Assessing the Role of Renal Grayscale Ultrasonography and Flowmetry in Correlation With Renal Function Tests Across Various Renal Diseases

## TL;DR

This study evaluates how well renal ultrasound and Doppler imaging predict kidney function changes in various kidney diseases.

## Contribution

The study compares grayscale and Doppler sonography's effectiveness in diagnosing kidney disease based on altered renal function tests.

## Key findings

- Chronic kidney disease showed 83% sensitivity with increased cortical echogenicity and elevated Doppler RI.
- Acute kidney injury had 75% sensitivity with increased renal parameters and elevated RI.
- Lupus nephritis patients had normal ultrasound findings despite elevated creatinine levels.

## Abstract

Background

Renal insufficiency, a critical concern in native and transplant kidneys, necessitates effective screening modalities for evaluation and management. Grayscale sonography has been a cornerstone in renal diagnostics, providing basic anatomical insights such as renal length, cortical thickness, and collecting system dilatation. Despite technological advancements, its impact on the differential diagnosis or management of renal disease remains limited, often showing normal findings in the presence of severe renal dysfunction. On the other hand, Doppler sonography, particularly the Doppler resistive index (RI), has shown potential in enhancing the assessment of renal dysfunction by quantifying alterations in renal blood flow and correlating with various renal pathologies and prognoses. Thus, this study aims to assess and compare the sensitivity of transabdominal and Doppler sonography as a diagnostic modality to evaluate medical renal diseases with altered renal function tests (RFTs).

Methodology

Participants included patients visiting the ultrasonography (USG) room at our hospital for USG of the kidneys, ureters, and bladder (USG KUB) and USG of the whole abdomen (USG W/A) with altered RFTs. Each underwent renal grayscale USG and RI measurement, alongside standard RFTs, aiming to investigate the relationship between USG and RI findings and RFT outcomes to assess their predictive accuracy for renal function. Renal grayscale USG assessed parameters including renal dimensions, echogenicity, corticomedullary differentiation, and RI. Data management and charting were conducted with Microsoft Excel 2021 and Microsoft Word 2021. IBM SPSS Statistics for Windows, Version 24 (IBM Corp., Armonk, NY) was utilized for data analysis. The analysis of variance (ANOVA) test examined relationships between renal parameters and RI across diagnostic groups. Furthermore, the chi-square test evaluated associations of renal ultrasound findings with RFTs and their significance.

Results

The study analyzed 93 patients with altered RFTs. Chronic kidney disease (CKD) affected 68 patients, primarily males in their fifth and sixth decades, showing reduced renal dimensions, increased cortical echogenicity, and elevated Doppler RI mean (RIm) with 83% sensitivity. Acute kidney injury (AKI) was found in 12 patients, mainly in their fourth decade, displaying increased renal parameters and elevated RIm with 75% sensitivity. Glomerular diseases, including nephrotic syndrome (NS) and nephritic syndrome (NeS), occurred in 9 patients, predominantly males in their fourth decade, with heightened renal cortical echogenicity and elevated RIm with 55.5% sensitivity. Lupus nephritis (LN) was detected in 4 female patients, despite normal renal parameters, showing elevated serum creatinine levels.

Conclusions

Doppler assessment of renal vascular waveforms effectively identifies chronic renal changes, aiding in the diagnosis of altered RFTs and guiding prognosis. While it detects typical changes like decreased size and parenchymal atrophy, it may not be as indicative of diabetic nephropathy. Key ultrasound indicators such as changes in echotexture and size, along with associated findings like ascites and effusions, help recognize altered renal function and minimize unnecessary interventions.