Magnetic resonance imaging diagnosis of renal infection in children

OBJECTIVE: To analyze the magnetic resonance imaging (MRI) manifestations of renal infection in children, evaluate the reliability of diffusion-weighted imaging (DWI) in detecting renal infections, and the difference in apparent diffusion coefficient (ADC) values between acute renal pelvis nephritis (APN), acute focal bacterial nephritis (AFBN) and renal abscess (RA). METHODS: Data for 513 children with a clinical orpathological diagnosis of acute kidney infection. Both MRI and voiding cystourethrography were performed in 28 cases. Group A comprised 17 cases of retrograde infection; Group B comprised 11 cases of blood–borne infection. The Kappa test was used to analyze differences in lesion DWI distribution between the groups, and the t-test was used to compare the ADC values. RESULTS: The MRI manifestations of pediatric renal infection were characteristic. The lesions had high-signal intensity on DWI and were located mainly in the renal cortex blood–borne infections versus the renal cortex and medulla in retrograde infections. The sensitivity and specificity of DWI for detecting lesions were 100% and 96%. The average ADC values of APN, AFBN, and RA lesions were lower than that of normal kidney tissue, with statistically significant differences between the three conditions; the ADC value of RA was the lowest, and that of APN was the highest. CONCLUSION: There were differences in the lesion distributions between renal retrograde and blood–borne infections. The quantitative decrease in ADC value may be related to the duration of the disease and the degree of renal damage.