ObjectiveTo analyze the diffusion weighted imaging(DWI) manifestations of acute focal bacterial nephritis in children against the reference standard of gadolinium-enhanced T1-weighted imaging(Gd-T1WI).

MethodsBetween February 2016 and December 2017, 26 cases of children (12 males, 14 females) with acute focal bacterial nephritis were examined by magnetic resonance(MR), including routine MR sequence(T1WI, T2WI), DWI, and Gd-T1WI-enhanced scan. The sensitivity and specificity of DWI in the diagnosis of acute focal bacterial nephritis were evaluated by Gd-T1WI-enhanced performance. Kappa test and McNemar test were applied for the calculation of the consistency among scanning sequences and calculation of repeatability among observers.

ResultsAmong the 26 children, 24 cases showed a wedge-shaped hypoperfusion area in the enhanced Gd-T1WI images, 21 had unilateral renal involvement, and 3 had bilateral renal involvement. Twenty-six cases had positive results on DWI images, 23 had unilateral renal involvement, and 3 had bilateral renal involvement. The lesions showed high signal on DWI, and the mean apparent diffusion coefficient value is lower than that of the normal renal tissue. The sensitivity and specificity of DWI detection were 100% and 92%, respectively. DWI demonstrated excellent agreement(k=0.923) with Gd-T1WI with no significant difference(P=0.25) in detection of abnormal lesions. All the observers used DWI to detect lesions with excellent reproducibility(k=0.76).

ConclusionsDWI can be used to diagnose acute focal bacterial nephritis with wedge-shaped or flaky high signal in children. The diagnostic effectiveness of DWI is basically the same as MRI enhanced scan, especially in people with renal insufficiency and inappropriate use of contrast agents.