Patients selecion
This retrospective study included VUS using SonoVue® and VCUG examinations performed between June 2011 and December 2015.
The total number of patients was 133,
with 263 pelvi-ureter units in children of mean age 21 months (range 29 days – 12 years).
There were 63 girls and 70 boys.
We included all children who suffered from recurrent urinary tract infections (UTI) with a proven positive urine culture or pelvicalyceal dilatation or in follow-up of VUR.
We excluded children who were incapable of voiding spontaneously and those with a neuropathic bladder.
Parents or legal guardians provided informed written consent,
and whenever possible the procedure was explained to the child.
Materials
VUS examinations were performed using a Logiq 9 high definition scanner (GE Healthcare) equipped with dedicated software for second-generation ultrasound contrast agent,
with a multifrequency convex probe.
The mechanical index (MI) setting ranged from 0.4 to 0.6.
The examinations were performed without sedation and with antibiotic prophylaxis.
Methods
VUS
A preliminary US examination of the kidneys and the bladder was performed in order to assess renal size,
structure and the presence of pelvicalyceal and ureter dilatation.
VUS was performed after intravesical administration of 2 ml of a second-generation ultrasound contrast agent (SonoVue,
Bracco,
Italy),
previously injected into a plastic bag of saline shaken gently to homogenise the contents.
The bladder was filled slowly to maximum capacity with the contrast medium solution.
The total volume of the bladder was calculated in a simple way according to the maximum bladder capacity: volume in milliliters = (age in years + 2) x 30.
During the filling phase,
longitudinal and transverse sections were acquired alternately to study the bladder,
the lower ureter,
and kidneys in the supine position.
When the bladder was full,
the voiding study started; the catheter wasn't removed during micturition making it possible to refill the bladder and carry out a cyclic study to increase the probability of detecting VUR (Urethral malformations were not included in the VUS evaluation).
The presence of UCA microbubbles in the ureters and/or pelvi-calyceal system was considered diagnostic of VUR and was graded according to the five-level International Reflux System of grading adapted to VUS (fig.
1- 2- 3).
VCUG
The bladder was filled with iodinated contrast material (Iopamidolo,
200 mg/ml iodine; Bracco Imaging Italia Srl) diluted with room-temperature normal saline (1:3) placed at 100 cm from the top of the examination bed.
The presence of contrast medium in the ureter or in the pelvicalyceal system was considered diagnostic of VUR and was graded according to the International Reflux System of grading (fig.
1- 2- 3).
In the first voiding cycle the catheter wasn’t removed during micturation.
It was removed in the last cycle,
to study the urethra.
VUS and VCUG were performed and independently evaluated by two pediatric radiologists.
Statistical analysis
Statistical analyses were performed using IBM SPSS Statistics version 17.0 for Windows (Microsoft,
Redmond,
WA).
The inter-rater agreement between VUS and VCUG was analysed using Cohen kappa.