Diffusion-weighted imaging of the kidneys in haemolytic uraemic syndrome

To evaluate the kidneys of patients with haemolytic uraemic syndrome (HUS) using diffusion-weighted imaging (DWI) and Doppler ultrasound (US) compared with healthy controls.

Fifteen patients (mean age 33.3 years; three male; 12 female) with diarrhoea-positive HUS and 15 healthy volunteers were prospectively evaluated with DWI and Doppler US. A total apparent diffusion coefficient (ADC_TOT), and ADCs predominantly reflecting microperfusion (ADC_LOW) and diffusion (ADC_HIGH) were calculated. Doppler US evaluated renal vascularity and flow.

When compared with controls, kidneys affected by HUS showed reduced cortical ADC values (ADC_TOT 1.79±0.22 vs. 2.04±0.1x10^-3 mm²/s, P 0.001), resulting in either low corticomedullary differences (11/15 patients) or an inverted corticomedullary pattern (4/15 patients). Reduction of cortical ADC values was associated with a decrease of cortical vascularity on Doppler US (ADC_TOT, P<0.001; ADC_LOW, P 0.047). Kidneys with complete absence of the cortical vasculature on Doppler US (four patients) also demonstrated limited diffusion (ADC_HIGH, P 0.002). Low glomerular filtration rate, requirement for haemodialysis during hospitalization, and longer duration of haemodialysis were associated with decreased cortical diffusivity (ADC_TOT: P 0.04, 0.007, and <0.001, respectively).

DWI shows qualitative and quantitative abnormalities in kidneys affected by HUS, thereby extending the non-invasive assessment of renal parenchymal damage.

• In HUS, DWI is feasible for functional characterization of kidney involvement. • Kidneys affected by HUS showed reduced cortical diffusivity. • Decreased cortical diffusivity was associated with lower kidney function. • Requirement and duration of haemodialysis was linked to degree of cortical alterations.