Phase inversion harmonic imaging improves assessment of renal calculi: a comparison with fundamental gray-scale sonography.

PURPOSE: To compare phase inversion harmonic imaging (PIHI) with fundamental imaging (FI) in the evaluation of renal calculi.

METHODS: Thirty adult patients with renal calculi (17 men, 13 women; mean age 44 years [range, 25-71]) underwent transabdominal sonographic examination of the urinary system. Both kidneys and renal calculi were examined with PIHI and FI. Overall renal conspicuity, calculus visibility, and clarity of posterior shadowing were assessed subjectively using a 4-point scale (0 being the worst, 3 being the best). The maximum diameter of the calculi was measured using both techniques. The effect of body mass index on qualitative scoring and quantitative measurements was evaluated.

RESULTS: PIHI improved overall renal conspicuity compared with FI (p < 0.001). The visibility of the calculi and clarity of posterior shadowing were significantly better with PIHI than with FI (p < 0.001 for both parameters). The maximum diameter of calculi was larger with PIHI than with FI (p < 0.001). The superiority of PIHI over FI regarding overall conspicuity of the kidney, visibility of the calculus, and clarity of posterior shadowing scores increased in the obese group (p < 0.001 for all 3 parameters). The mean calculus diameter difference between the 2 techniques was significantly higher in the obese group.

CONCLUSION: The routine use of PIHI is recommended in the evaluation of renal calculi.