SONOGRAPHIC EVALUATION OF GALLSTONE BURDEN IN HUMANS

A prospective blind study was performed to compare sonographic with po stoperative findings of gallstone burden in 34 patients (10 males, 24 females, mean age 52 years). Gallstone size was assessed in single cal culi n=15) by measuring the largest diameter by ultrasonography (US). The ellipsoid algorithm was used to estimate US volume for both single and multiple gallstones. After cholecystectomy, diameters were measur ed in single stones; stone volume was assessed by the ellipsoid formul a (single stones) and fluid displacement (single and multiple stones). Stone volumes assessed by the ellipsoid formula and fluid displacemen t correlated closely (r=0.98; p<0.0001, n=15). In the case of single g allstones, the mean length assessed by US was 25.3+/-3.2 mm and compar ed well with the value measured ''in vitro'' (24.8+/-3.1 mm). A highly significant and positive relationship existed between the sonographic size and the true stone size (r=0.93; p<0.0001, n=15). Stone volumes assessed ''in vivo'' and by fluid displacement were comparable and cor related for both single (US: 6.6+/-1.3 vs fluid displacement: 5.8+/-1. 4 ml; r=0.79; p<0.0005, n=15) and multiple stones (US: 3.8+/-0.8 vs fl uid displacement: 3.7+/-0.8 ml; r=0.85; p<0.0001, n=19). We conclude t hat: (i) sonography can reliably quantify the greatest diameter of sin gle stones, although limitations do exist in the case of larger single or multiple calculi; (ii) the sonographic estimation of gallstone vol ume can be achieved by using the ellipsoid formula, which is most usef ul in the presence of gallstone clusters.