Feasibility of superb microvascular imaging to detect high-grade vesicoureteral reflux in children with urinary tract infection.

OBJECTIVE: To evaluate superb microvascular imaging (SMI) for the detection of high-grade vesicoureteral reflux (VUR).

METHODS: We reviewed the patients with urinary tract infection who underwent renal US with SMI and VCUG. The subjects were divided into a VUR group, which included 17 patients (20 kidney units, KU) with high-grade reflux (grade 4 or 5) on VCUG, and a group without VUR including the same numbers of subjects. The direction of urine movement at the distal ureter and the renal pelvis was reviewed on SMI. SMI and VCUG results were compared.

RESULTS: Urinary flow "jets" into the bladder and direction of the flow were detectable on all SMI examinations in both groups. In the group with VUR, 20 KUs had grade 4 (n = 11) or grade 5 (n = 9) reflux (bilateral VUR in 3 patients). Among 20 KUs with VUR, 15 (75%) showed a reversed ureteral jet and/or renal pelvic swirl sign on SMI. None of the patients in the group without VUR showed those findings on SMI.

CONCLUSION: SMI enables detection of the direction of urinary flow. The presence of a reversed ureteral jet and/or renal pelvic swirl sign correlates with high-grade VUR with 75% accuracy.

KEY POINTS: • Superb microvascular imaging is feasible in children with urinary tract infection. • SMI enables detection of the direction of urinary flow. • Presence of reversed flow correlates with high-grade vesicoureteral reflux.