Harmonic versus conventional ultrasound imaging of the urinary tract in children

Background:Harmonic imaging (HI) is a relatively new US method. Its usefulness in children has yet to be determined. Objective: To evaluate the value of HI in urinary tract imaging of infants and children. Materials and methods: The bladder and kidneys of 29 unselected patients, aged 2 months to 12.8 years (mean, 6.8 years), were examined from ventral and dorsal approaches using conventional (=fundamental) imaging (FI) (6.5 and 3.4 MHz) and HI (3.3 MHz). In addition to global image quality, visualization of bladder wall, retrovesical space, renal contrast to liver/spleen, the pelvicalyceal systems, and the difference between cortex and medulla were assessed. Parameters were rated by two independent examiners and statistical analysis was performed. Results: There were significant differences between the three imaging settings for all parameters studied (P < 0.003). With the dorsal approach, HI was superior to FI for all parameters analysed (P < 0.05). Using the ventral approach, a significant improvement of imaging with HI was found for the bladder and the renal pelvis (P < 0.02). Conclusions: HI is a useful additional tool for imaging the urinary tract in children of all ages. The method particularly improves visualization of the bladder and the kidney from a dorsal approach.