Systemic sclerosis (SSc) is one of the systemic autoimmune diseases, which is characterized by immune dysregulation, vasculopathy and progressive fibrosis [1]. SSc frequently involves multiple organs including skin, lung, gastrointestinal tract, heart, and kidney [2,3]. The involvement of kidney may lead to renal insufficiency or even scleroderma renal crisis (SRC). It has been shown that 1–14% of SSc patients suffered from SRC [4]. As a life-threatening complication, SRC presents with acute kidney injury and pathologically with intimal thickening and fibrotic ‘onion-skinning’ of the interlobular and arcuate renal arteries [5,6]. However, the renal involvement in SSc may remain unnoticed at subclinical stage until late in progression [7], suggesting the needs of early diagnosis.

According to the existing criteria, diagnosis of SRC depends on the assessment of blood pressure, serum creatinine, urine red blood cells, urine proteins, estimated glomerular filtration rate (eGFR) calculated by serum creatine, and the results of renal biopsy [8]. However, the changes of blood and urine indicators only reflect the global status of individuals and may be later than microstructural and functional impairment of kidney. The invasive procedures of renal biopsy may increase the risk of complications. Although GFR measured by nuclear scintigraph is the gold standard for assessing renal function, it was unsuitable for routine clinical use because of its ionizing radiation and tedious process [9]. Renal ultrasound was also utilized in the previous study to measure renal blood flow and evaluate the renal morphologic abnormalities and renal artery stenosis with a limited resolution [10]. In contrast, MR quantitative imaging enables non-invasive investigation of renal morphology [11], function [12] and perfusion [13]. We hypothesized that MR quantitative imaging has the potential to characterize the impairment of renal microstructure and function in SSc patients.

This study aimed to characterize renal microstructure and function in SSc patients using multiparametric MR quantitative imaging. The multiparametric MR quantitative imaging sequences utilized in this study were diffusion weighted imaging (DWI), blood oxygen level dependent (BOLD) and saturated multi-delay renal arterial spin labeling (SAMURAI) proposed by Ning et al. [14], which enables to acquire multi-delay arterial spin labeling and T1 map of the kidneys simultaneously with excellent reproducibility.