Susanne Stads, Niels G. Venneman, Robert C.H. Scheffer, Melvin Samsom, Karel J. van Erpecum
Since impaired gallbladder emptying contributes to gallstone formation, the evaluation of gallbladder motility requires accurate methodology. Recently developed 3-dimensional ultrasonography may take into account various gallbladder shapes more accurately than conventional 2-dimensional ultrasonography. Therefore, volumes of water-filled balloons of various sizes were determined in vitro by 2-dimensional ultrasonography with the sum of cylinders method and by 3-dimensional ultrasonography. Also, in 15 gallstone patients and 6 healthy volunteers, fasting gallbladder volumes and postprandial motility were determined by both methods. Volumes of water-filled balloons as measured by both methods correlated strongly with true volumes (R= 0.93 for 2-dimensional and R = 0.98 for 3- dimensional ultrasonography). Gallbladder volumes measured by both methods were also correlated (R = 0.66, P < 0.001). In gallstone patients, 3-dimensional ultrasonography yielded smaller gallbladder volumes than 2-dimensional ultrasonography (P = 0.007), but not in healthy subjects. With both methods, gallstone patients exhibited decreased postprandial gallbladder motility compared to healthy subjects. In conclusion, gallbladder volume measurements by 3-dimensional and 2-dimensional ultrasonography are strongly correlated. Nevertheless, in gallstone patients, gallbladder volumes by 3-dimensional ultrasonography tend to be smaller than by 2-dimensional ultrasonography, possibly due to interference of gallstones with the volume measurement.
Key words. Gallstone, ultrasonography