One-stop assessment of renal function and renal artery in hypertensive patients with suspected renal dysfunction: non-enhanced MRI using spatial labeling with multiple inversion pulses

The added value of superb microvascular imaging for renal cortical thickness measurement in chronic kidney disease

PURPOSE

The aim of this study was to evaluate renal parenchymal thickness and renal cortical thickness measurements on brightness mode ultrasound (B-mode US) and B-mode US + Superb Microvascular Imaging (SMI) technique, comparing with computed tomography (CT) or magnetic resonance imaging (MRI) serving as a reference standard.

METHODS

Renal parenchymal thickness and renal cortical thickness measurements were obtained from B-mode US, B-mode US + SMI, and CT/MRI in a group of healthy subjects and a group of patients with chronic kidney disease (CKD). The mean differences and correlations of renal parenchymal thickness and renal cortical thickness were analyzed using dependent pair t-test and Pearson's correlation, respectively.

RESULTS

The mean difference in renal cortical thickness measurements between B-mode US + SMI and CT/MRI was lower than the mean difference between B-mode US alone and CT/MRI. Additionally, renal cortical thickness measured using B-mode US + SMI showed a stronger correlation with values obtained from CT/MRI than values measured using standard B-mode US alone.

CONCLUSION

The measurement of renal cortical thickness by B-mode US + SMI is more accurate than that by B-mode US alone.

Non-contrast-enhanced MR angiography of left gastric vein in patients with gastroesophageal varices: morphology and blood supply analysis

OBJECTIVES

To investigate the feasibility of non-contrast-enhanced MR angiography (NCE-MRA) in evaluating the morphology and blood supply of left gastric vein (LGV) in patients with gastroesophageal varices.

METHODS

Between March 2021 and October 2022, patients with gastroesophageal varices and who underwent NCE-MRA were retrospectively reviewed. In order to evaluate the blood supply of LGV, superior mesenteric vein (SMV) and splenic vein (SV) were visualized separately by using inflow-sensitive inversion recovery sequence. Two radiologists independently assessed the image quality, determined the origination and the blood supply of LGV, and measured the diameter of LGV. The origination and diameter of LGV were compared between NCE-MRA and contrast-enhanced CT. Differences in blood supply were compared between LGVs with different originations.

RESULTS

A total of 53 patients were enrolled in this study and the image quality was categorized as good or excellent in 52 patients. No significant differences were observed in visualizing the origination and the diameter of LGV between NCE-MRA and contrast-enhanced CT (p > .05). The blood supply of LGV was related to its origination (p < .001). Most LGVs with SV origination were supplied by SV. If LGV was originated from the portal vein (PV), about 70% of them were supplied by both SV and SMV. Compared with LGVs with SV origination, LGVs with PV origination showed more chance to receive blood from SMV (p < .001).

CONCLUSION

Non-contrast-enhanced MR angiography appears to be a reliable technique in evaluating the morphology and blood supply of LGV in patients with gastroesophageal varices.

CLINICAL RELEVANCE STATEMENT

Non-contrast-enhanced MR angiography provides valuable information for the management of gastroesophageal varices. Especially, it benefits patients with renal insufficiency.

KEY POINTS

• Non-contrast-enhanced MR angiography using inflow-sensitive inversion recovery technique can be used for evaluating not only morphology as CT but also blood supply of left gastric vein. • The blood supply of left gastric vein is related to its origination and left gastric vein with portal vein origination shows more chance to receive blood from superior mesenteric vein.

Non-contrast-enhanced magnetic resonance urography for measuring split kidney function in pediatric patients with hydronephrosis: comparison with renal scintigraphy

BACKGROUND

Split kidney function (SKF) is critical for treatment decision in pediatric patients with hydronephrosis and is commonly measured using renal scintigraphy (RS). Non-contrast-enhanced magnetic resonance urography (NCE-MRU) is increasingly used in clinical practice. This study aimed to investigate the feasibility of using NCE-MRU as an alternative to estimate SKF in pediatric patients with hydronephrosis, compared to RS.

METHODS

Seventy-five pediatric patients with hydronephrosis were included in this retrospective study. All patients underwent NCE-MRU and RS within 2 weeks. Kidney parenchyma volume (KPV) and texture analysis parameters were obtained from T2-weighted (T2WI) in NCE-MRU. The calculated split KPV (SKPV) percent and texture analysis parameters percent of left kidney were compared with the RS-determined SKF.

RESULTS

SKPV showed a significant positive correlation with SKF (r = 0.88, p < 0.001), while inhomogeneity was negatively correlated with SKF (r =  - 0.68, p < 0.001). The uncorrected and corrected prediction models of SKF were established using simple and multiple linear regression. Bland-Altman plots demonstrated good agreement of both predictive models. The residual sum of squares of the corrected prediction model was lower than that of the uncorrected model (0.283 vs. 0.314) but not statistically significant (p = 0.662). Subgroup analysis based on different MR machines showed correlation coefficients of 0.85, 0.95, and 0.94 between SKF and SKPV for three different scanners, respectively (p < 0.05 for all).

CONCLUSIONS

NCE-MRU can be used as an alternative method for estimating SKF in pediatric patients with hydronephrosis when comparing with RS. Specifically, SKPV proves to be a simple and universally applicable indicator for predicting SKF.

Assessment of renal function using magnetic resonance quantitative histogram analysis based on spatial labeling with multiple inversion pulses

Background

The incidence of chronic kidney disease (CKD) is high, and is easy to develop into end-stage renal disease (ESRD), which requires kidney dialysis or kidney transplantation. Therefore, we want to explore the clinical value of magnetic resonance quantitative histogram analysis based on spatial labeling with multiple inversion pulses (SLEEK) in assessing renal function in the early stage.

Methods

One hundred and twenty-nine patients underwent abdominal MRI examination, including a coronal SLEEK sequence. The patients were divided into the control group [CG, 47 cases, estimated glomerular filtration rate (eGFR) >90], the mild renal function impairment (mRI) group (48 cases, eGFR =60–90), and the moderate to severe renal function impairment (m-sRI) group (34 cases, eGFR <60). Two experienced radiologists delineated cortex and medulla regions of interest (ROIs) on SLEEK images to obtain cortex and medulla quantitative histogram parameters [Mean, Median, Percentiles (5^th, 10^th, 25^th, 75^th, and 90^th), Skewness, Kurtosis, and Entropy] using FireVoxel. These histogram parameters were compared by proper statistical methods such as one-way analysis of variance, the χ² test, and receiver operating characteristic (ROC) curve analysis.

Results

Four histogram parameters (Inhomogeneity_cortex, Skewness_cortex, Kurtosis_medulla, and Entropy_medulla) differed significantly between the CG and the mRI group. One medulla (Entropy_medulla) and nine cortex (Mean_cortex, Median_cortex, Kurtosis_cortex, Entropy_cortex, and 5^th, 10^th, 25^th, 75^th, and 90^th Percentile_cortex) histogram parameters were significantly different between the m-RI and m-sRI groups. The most relevant parameter to eGFR was Inhomogenity_cortex (r=−0.450, P<0.001). Inhomogeneity_cortex had the largest area under the curve (AUC) for differentiating the mRI group from the CG (AUC =0.718; 95% CI: 0.616–0.806), while 25^th Percentile_cortex generated the largest AUC (AUC =0.786; 95% CI: 0.681–0.869) for differentiating the mRI and m-sRI groups.

Conclusions

Quantitative histogram parameters based on a SLEEK sequence can be used to supplement renal dysfunction assessment. Cortex histogram parameters are more valuable for evaluating renal function than medulla histogram parameters.