Renal diffusion-weighted imaging in diabetic nephropathy: correlation with clinical stages of disease

Abstract

Original Article PURPOSE We aimed to assess the correlation between renal apparent diffusion coefficient (ADC) values measured by diffusion-weighted imaging (DWI) and the clinical stages of diabetic nephropathy. MATERIALS AND METHODS DWI (b value, 0 and 600 s/mm2 ) was performed in 78 patients with clinically confirmed diabetic nephropathy (study group) and 22 volunteers without diabetes mellitus or any renal disease (control group). The mean ADCs were calculated from multiple region-of-interest circles positioned in the renal cortex. Diabetic nephropathy was clinically categorized into five stages based on the values of urinary albumin excretion and glomerular filtration rate (GFR). RESULTSMean renal ADC values of patients with stage 3 or 4 disease were significantly lower than those in patients with stage 1 or 2 disease and the control group (P < 0.001). ADC values of patients with stage 5 disease were significantly lower than those in patients with stage 4 (P = 0.003), stage 3 (P = 0.020), stages 2 and 1, and the control group (P < 0.001). Significant correlations were found between mean renal ADC values and clinical stages of diabetic nephropathy (r=−0.751, P < 0.001), between mean renal ADC values and estimated GFR values (r=0.642, P < 0.001), and between mean renal ADC values and urinary albumin excretion (r=−0.419, P < 0.001). CONCLUSIONRenal ADC values show a significant correlation with clinical stages of diabetic nephropathy. As a relatively simple and noninvasive tool without contrast media administration, renal quantitative DWI may potentially play a role in making clinical decisions in the follow-up of diabetic patients. Diabetic nephropathy is classically defined as a clinical syndrome characterized by persistent albuminuria, a relentless decline in glomerular filtration rate (GFR) progressing to end-stage renal disease, raised arterial blood pressure, and enhanced cardiovascular morbidity and mortality (1). In diabetic patients, renal functional deterioration is the result of heterogeneous renal structural changes, including glomerular basal membrane thickening and mesangial expansion, extracellular matrix accumulation, mesangiolysis, reduced podocyte number, microaneurysm formation, arteriolar hyalinosis which ultimately leads to glomerulosclerosis, tubular atrophy, interstitial expansion, and fibrosis (2). Renal damage occurs in multiple stages. Throughout its early stages, diabetic nephropathy has no symptoms. Persistent microalbuminuria is a predictor of the development of clinical nephropathy. Microalbuminuria has been proposed as a marker of widespread endothelial dysfunction and indicates microvascular damage (3). Better understanding of the mechanisms that lead to structural and functional changes in the diabetic kidney may facilitate the development of more effective follow-up and treatment modalities. Diagnostic tests that help identify early microvascular damage at an early stage will provide significant benefits to get the disease under control. Quantitative diffusion-weighted magnetic...

Magnetic Resonance Imaging of the Fibrotic Kidney

“…Numerous studies in both animal models and humans have shown significant decrease in ADC in diseased kidneys compared with healthy kidneys. [10][11][12][13][14][15][16][17][18][19][20][21] Some animal and human studies have directly compared ADC with degree of fibrosis in biopsy or postmortem histology. In a mouse model of renal fibrosis caused by unilateral ureter ligation, ADC decreased in the cortex of fibrotic kidneys, and the amount of decrease in ADC was correlated with cellular density and a-smooth muscle actin, markers of renal fibrosis.…”

“…11,12,14 Several human studies have shown significant associations between eGFR or serum creatinine and ADC. 10,13,14,16,[20][21][22] An extension of DWI known as diffusion tensor imaging (DTI) gives additional information about the organization of tissue. In DTI, diffusion imaging is performed repeatedly with diffusion gradients oriented in different directions.…”

Diabetic Nephropathy – Pathophysiology: An Overview

“…These forces includes (A) hydrostatic pressure inside the glomerular capillaries depends upon pressure at afferent arteriolar end(glomerular hydrostatic pressure PG), which promotes fi ltration (B) the hydrostatic pressure in Bowman's capsule (PB) outsides the capillaries, which opposes fi ltration; (C) the colloid osmotic pressure of the glomerular capillary plasma proteins (πG), which opposes fi ltration; and (D) the colloid osmotic pressure of the proteins in Bowman's capsule (πB), which promotes fi ltration. The GFR is expressed as: [33][34][35][36][37]. GFR = K f X (PG -PB -πG + πB) Figures 6,7).…”

Diffusion-weighted magnetic resonance imaging in diabetic retinopathy

“…They concluded that their results supported the association between DR and brain injury. Lu et al [16] and Çakmak et al [17] Diabetes mellitus affects the extracellular matrix and connective tissue throughout the body via non-enzymatic glycation and abnormal cross-linking of collagen. As the vitreous is also an extracellular matrix, of which collagen constitutes an important portion, it may show changes through liquefaction and syneresis in patients with DM, even in those without apparent DR. [18,19].…”