Use of diffusion tensor imaging in assessment of renal fibrosis in lupus nephritis: Cross sectional study

Omneya Salah Hassan; Sherif Aziz Zaki; Mona Abd-Alkader Salem; Ahmed Hafez Afifi

Omneya Salah Hassan Faculty of Medicine, Alexandria University
Sherif Aziz Zaki, Professor of Internal Medicine Faculty of Medicine, Alexandria University
Mona Abd-Alkader Salem, Professor of Pathology Faculty of Medicine, Alexandria University
Ahmed Hafez Afifi, Professor of Radiodiagnosis Faculty of Medicine, Alexandria University

Keywords: Lupus nephritis, Diffusion tensor, Magnetic resonance imaging, Renal fibrosis

Abstract

Background: Lupus nephritis (LN) is a major risk factor for morbidity in systemic lupus erythematosus (SLE) and 10% of patients with LN will develop end stage renal disease. Renal biopsy is mandatory in almost all patients with LN, but sometimes it is not feasible and may be associated with complications. Therefore, the identification of a non-invasive tool for assessment of renal structure and function is vital. The aim of our study is to explore the association of diffusion tensor magnetic resonance imaging (MRI) parameters as apparent diffusion coefficient (ADC) and fractional anisotropy (FA) with measurements of renal functions and renal histopathological changes especially markers of fibrosis in a cohort of patients with LN.

Methods: The study was conducted on thirty patients diagnosed with LN and thirty healthy volunteers representing the control group. All candidates were subjected to measurements of renal functions, estimated glomerular filtration rate (eGFR), SLE disease activity index (SLEDAI) score and underwent diffusion tensor MRI of kidneys. Renal biopsy was done for the cases group within one week of the MRI. In addition to the routine histological examination, immunohistochemical staining using anti-collagen III antibody was done as a measure of fibrosis.

Results: The mean cortical ADC, medullary ADC, cortical FA and medullary FA in patients with LN were significantly lower than the control group and they correlated positively with eGFR. These markers also correlated negatively with the pathological chronicity index and they showed a downward trend with increasing interstitial fibrosis score. Δ ADC can somehow differentiate between some classes of LN.

Conclusions: Diffusion tensor imaging (DTI) is a useful non-invasive tool which can help in assessment of renal impairment in patients with LN, it can also give an idea about the degree of fibrosis and chronicity which can influence treatment decisions.