The utility of magnetic resonance imaging for noninvasive evaluation of diabetic nephropathy

Abstract

Background Noninvasive quantitative measurement of fibrosis in chronic kidney disease (CKD) would be desirable diagnostically and therapeutically but standard radiologic imaging is too variable for clinical usage. By applying a vibratory force, tissue shear wave stiffness can be measured by magnetic resonance elastography (MRE) that may correlate with progression of kidney fibrosis. Since decreased kidney perfusion decreases tissue turgor and stiffness, we combined newly available three-dimensional MRE shear stiffness measurements with MR arterial spin labeling (ASL) kidney blood flow rates to evaluate fibrosis in diabetic nephropathy. Methods Thirty individuals with diabetes and Stage 0–5 CKD and 13 control individuals without CKD underwent noncontrast MRE with concurrent ASL blood flow measurements. Results MRE cortical shear stiffness at 90 Hz was decreased significantly below controls in all CKD stages of diabetic nephropathy. Likewise, ASL blood flow decreased progressively from 480 ± 136 mL/min/100 g of cortical tissue in controls to 302 ± 95, 229 ± 7 and 152 ± 32 mL/min/100 g in Stages 3, 4 and 5 CKD, respectively. A magnetic resonance imaging (MRI) surrogate for the measured glomerular filtration fraction [surrogate filtration fraction = estimated glomerular filtration rate (eGFR)/ASL] decreased progressively from 0.21 ± 0.07 in controls to 0.16 ± 0.04 in Stage 3 and 0.10 ± 0.02 in Stage 4–5 CKD. Conclusions In this pilot study, MRI with ASL blood flow rates can noninvasively measure decreasing kidney cortical tissue perfusion and, with eGFR, a decreasing surrogate filtration fraction in worsening diabetic nephropathy that appears to correlate with increasing fibrosis. Differing from the liver, MRE shear stiffness surprisingly decreases with worsening CKD, likely related to decreased tissue turgor from lower blood flow rates.

Evaluation of Renal Fibrosis by Mapping Histology and Magnetic Resonance Imaging

“…Most of the data from transplanted kidneys showed that MRE values were negatively associated with eGFR and fibrosis burden. Nevertheless, as authors from recent studies suggested, to our surprise, differing from that in the liver and allografts, MRE shear stiffness decreases with worsening CKD in IgA nephropathy [15], lupus nephritis [16], and diabetic nephropathy [17]. In IgA nephropathy, which is the most commonly studied glomerular nephritis, although 16 patients with biopsy-proven IgAN were studied, the investigators found that advanced stage IgAN was associated with renal softening and restricted water diffusion [15].…”

“…MRE combines imaging with the assessment of acoustic waves for the quantitative determination of the viscoelastic properties of tissues based on their response to external mechanical vibrations [29]. To date, MRE is a well-established technique for liver fibrosis imaging [30-32]; however, there are only a few high-quality studies evaluating MRE in human kidney allografts [8, 10, 33] and in native kidneys [9, 15-17]. The kidney possesses specific features rendering it more difficult to image since it is a heterogeneous organ.…”

“…Their data suggested that whole-kidney stiffness correlated with the biopsy-derived Banff fibrosis score. Nevertheless, recently, at least 3 articles from native kidneys showed that MRE values had a negative relationship with fibrosis degree in IgA nephropathy [15], lupus nephritis [16], and diabetic nephropathy [17].…”

The Role of Diffusion-Weighted MRI and Apparent Diffusion Coefficient in Assessment of Diabetic Kidney Disease: Preliminary Experience Study

“…MRI is an emerging noninvasive tool to assess kidney fibrosis in diabetic disease. 10 Ultrasound failed as a noninvasive tool because renal size, cortical thickness and cortical echogenicity are preserved until ESRD occurs. 11 In addition, ultrasound findings are operatordependent, and the renal volume is significantly affected by the degree of hydration at the time of examination.…”

Perspectives on the Role of Magnetic Resonance Imaging (MRI) for Noninvasive Evaluation of Diabetic Kidney Disease

“…This result was supported by a significant correlation between RBF and GFR, estimated by creatinine and cystatin-C. Other studies have shown similar results. Recently, Brown et al analyzed in a pilot study the ability of ASL to provide information on fibrotic changes occurring during DKD [51]. To do so, they studied diabetic subjects from early to advanced categories of kidney disease and compared them with healthy volunteers using magnetic resonance elastography and ASL.…”