Abstract
ObjectiveUrinary tract infection (UTI), one of the most common bacterial infections occurring during infancy and early childhood, is frequently associated with vesicoureteral reflux (VUR). Although several guidelines recommend performing ultrasonography as a screening test, its utility is not adequate and appropriate screening tests are strongly desirable. In this study, we evaluate the use of magnetic resonance imaging (MRI) as a screening test for VUR in children with UTI.MethodsWe prospectively studied 108 patients with suspected UTI between April 2014 and March 2016. UTI was diagnosed on the basis of diffusion-weighted MRI (DW-MRI) and urine culture findings. We measured ureteral dilatation using MRI in 96 patients with UTI and assessed the relationship between ureteral dilatation in MRI and VUR in 46 patients who underwent voiding cystourethrography (VCUG).ResultsAmong 108 patients, 88 and 8 were diagnosed with upper and lower UTI, respectively. Among 46 patients who underwent VCUG, 23 had VUR (14 low grade and 9 high grade). Patients with ureteral dilatation detected on MRI had VUR more frequently than those without ureteral dilatation (any grades VUR, 71% vs. 32%; P = 0.02; high-grade VUR, 38% vs. 2%, P = 0.007). Overall, ureteral dilatation findings on MRI achieved sensitivity 65.2% and specificity 73.9% as a screening test for VUR. In addition, DW-MRI achieved sensitivity 100% and specificity 81.8% in the diagnosis of upper UTI.ConclusionThese findings suggested that MRI is a valuable tool for screening of VUR as well as diagnosis of upper UTI.
Highlights
Urinary tract infection (UTI), one of the most common bacterial infections occurring in infancy and early childhood, is divided into two categories: “lower UTI” without renal inflammation and “upper UTI” with renal inflammation, including acute pyelonephritis (APN), acute focal bacterial nephritis (AFBN), and renal abscess.[1, 2] Because upper UTI frequently causes renal scarring and results in renal dysfunction, early diagnosis and early treatment are important.[3,4,5] diagnosis of upper UTI sometimes is challenging because of nonspecific clinical features, especially in infants.[6]
Patients with ureteral dilatation detected on magnetic resonance imaging (MRI) had vesicoureteral reflux (VUR) more frequently than those without ureteral dilatation
Ureteral dilatation in MRI predicts VUR in UTI. These findings suggested that MRI is a valuable tool for screening of VUR as well as diagnosis of upper UTI
Summary
Urinary tract infection (UTI), one of the most common bacterial infections occurring in infancy and early childhood, is divided into two categories: “lower UTI” without renal inflammation and “upper UTI” with renal inflammation, including acute pyelonephritis (APN), acute focal bacterial nephritis (AFBN), and renal abscess.[1, 2] Because upper UTI frequently causes renal scarring and results in renal dysfunction, early diagnosis and early treatment are important.[3,4,5] diagnosis of upper UTI sometimes is challenging because of nonspecific clinical features, especially in infants.[6]. Urine culture is considered negative in approximately 40% of patients with AFBN, which is a severe form of APN.[7] negative urine culture results cannot rule out the possibility of upper UTI, and imaging tests, including ultrasonography (US), contrast-enhanced computed tomography (CECT), and 99mTechnetium (99mTc) dimercaptosuccinic acid (DMSA) renal scintigraphy, often are required to diagnose upper UTI.[8] In addition to these imaging procedures, some preceding studies showed the use of magnetic resonance imaging (MRI), especially diffusion-weighted magnetic resonance imaging (DW-MRI) in the diagnosis of APN.[9, 10]. MRI is reportedly more accurate in the diagnosis of renal scarring compared with DMSA scan.[11]
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