Harmonic US imaging of vesicoureteric reflux in children: usefulness of a second generation US contrast agent.
BACKGROUND
Contrast-enhanced voiding urosonography (VUS) is largely accepted both for the diagnosis and follow-up of vesicoureteric reflux (VUR) in children.


OBJECTIVE
To evaluate the usefulness of contrast-enhanced second-harmonic VUS in the diagnosis and grading of VUR, using a second-generation contrast agent.


METHODS
Eighty consecutive children were prospectively studied with contrast-enhanced second-harmonic VUS. All children received a second-generation contrast medium, constituted by phospholipid-stabilized microbubbles of sulphur-hexafluoride (SonoVue, Bracco, Milan, Italy). US monitoring of the bladder, of the retrovesical space and of the kidneys was performed using, alternatively, both tissue-harmonic and contrast-harmonic modes. In those young boys where VUR was depicted at VUS, examination was completed with transperineal, sagittal urethral exploration during micturition. VUR was graded in five steps and diagnoses were compared with voiding cystourethrography (VCUG).


RESULTS
VUR was diagnosed in 52 reno-ureteral units with VUS. In 49 of these reno-ureteral units, VCUG confirmed the presence of VUR. In comparison to VUS, sensitivity and negative predictive value of VCUG were inferior. The grade of VUR detected at VUS was higher than that detected at VCUG in three units. In no case was the grade of VUR detected at VCUG higher than the one detected at VUS. The differences between VUS and VCUG in grading VUR were statistically significant (p=0.02). Imaging of the normal posterior urethra was skilfully demonstrated with US in 15 young boys with VUR. No statistically significant differences were found between tissue-harmonic and contrast-harmonic mode (p=0.102).


CONCLUSIONS
Contrast-enhanced second-harmonic VUS is a sensitive and easy technique for the evaluation of VUR. A second-generation US contrast medium such as SonoVue, if available, should be the first choice as the dose required for one examination is much lower and consequently significant reduction of contrast agent cost is possible.
Ascenti
Giorgio
G
Department of Radiological Sciences, University of Messina, Via Giordano Bruno, 53, 98163 Messina, Italy. gascenti@unime.it
Zimbaro
Giovanni
G
Mazziotti
Silvio
S
Chimenz
Roberto
R
Fede
Carmelo
C
Visalli
Carmela
C
Scribano
Emanuele
E
D002675:Child, Preschool; D003287:Contrast Media; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D010743:Phospholipids; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D018709:Statistics, Nonparametric; D013459:Sulfur Hexafluoride; D014463:Ultrasonography; D014718:Vesico-Ureteral Reflux / Q000000981:diagnostic imaging*
D003287:Contrast Media; D010743:Phospholipids; C420843:contrast agent BR1; D013459:Sulfur Hexafluoride