Contrast-enhanced harmonic imaging for the diagnosis of vesicoureteral reflux in pediatric patients

OBJECTIVE. Harmonic imaging Busing phase or pulse inversion technology is a new sonographic graphic diagnostic modality that has the potential to prod uce images of a higher quality than can be obtained with the conventional m ethod. The aim of this study was to compare both types of harmonic modaliti es-tissue and contrast harmonic imaging-with the fundamental imaging mode i n contrast-enhanced B-mode sonographic diagnosis of vesicoureteral reflux. SUBJECTS AND METHODS; Fifty-four children presenting for diagnostic examina tion of vesicoureteral reflux underwent standard sonography of the urinary tract in the fundamental mode, followed by intravesical administration of a galactose-based contrast medium containing microbubbles. The contrast-enha nced sonography was conducted by scanning the bladder and each kidney in tr ansverse and longitudinal planes, from ventral and dorsal views, consecutiv ely in B-mode using fundamental, contrast harmonic, and tissue harmonic ima ging modalities. Soft-touch buttons on the console screen were used to alte rnate between the three imaging options, so that switching from one modalit y to the other could be done almost instantaneously. For comparison, in eac h patient, we selected one set of contrast-enhanced images of the bladder a nd two sets, one ventral and one dorsal, of the kidney. In a series, the im ages were compared and ranked from 1 to 3, with 1 being the best, with rega rd to sonomorphology (demarcation of the retrovesical space and renal pelvi s as the potential sites to look for vesicoureteral reflux) and reflux dete ction and conspicuity, if present. RESULTS. In all, 248 sets of images were available for comparison. The deli neation of both the retrovesical space and the renal pelvis was found to be best with tissue harmonic imaging in 84% and 96% of the image sets, respec tively (p <0.01). Forty-one sets of images were compared from 27 kidney-ure ter image units of 22 children (41%) with reflux. The refluxing microbubble s were much more conspicuous in the harmonic imaging mode (tissue harmonic, 100%; contrast harmonic, 93%) than in the fundamental mode (p <0.01). In e ight kidney-ureter units, the reflux was detected only by using the harmoni c imaging modalities. CONCLUSION. Visualization of the urinary tract and detection of ultrasound contrast media is significantly improved by the use of the harmonic imaging modalities. When both fundamental and harmonic imaging options are availab le, we recommend harmonic imaging for contrast-enhanced sonographic diagnos is of vesicoureteral reflux.