In the 76 patients studied, the calibre of the common bile duct was found
to be larger than normal, with a value of 4.74±2.3 mm, and a range
of 1.6-13 mm. The results obtained by the 3 operators in the evaluation of
the bile duct images showed high diagnostic accuracy of the harmonic image
in the study of the distal third, bile duct content, and the relations between
the bile duct and adjacent structures.
|TABLE II.-Radiologist's evaluations
of the imagines obtained by conventional US and THI.
| CONV. US
All of the three radiologists (A, B, C) rated the THI results better that
those of conventional US (p>0.0001,Wilcoxon sign rank test).
The mean values and the standard deviation of the differences between THI
and conventional US were respectively 1.25 (0.57), 1.22 (0.51), 1.09 (0.57)
for radiologists A, B, C. There was no significant variation in the three
observers’ evaluations of older patients (>74 years) and younger
patients (p=0.35, Wilcoxon rank- sum test). Table II shows each operator’s
ratings of the conventional US and THI images.
|Fig. 1. - Mean values of the
three radiologists’ evaluations of the common bile duct conventional
US and THI.
Figure 1 shows the mean values of the three operators’ evaluations
of the common bile duct using conventional US and harmonic imaging. It is
clear that the use of harmonic imaging eliminates the 30% inadequate examinations
found in conventional US. Moreover, the number of diagnoses of bile duct lithiasis
(10 patients) was higher with harmonic imaging than conventional US (5 patients),
with a diagnostic gain of 50%. The calculation of the agreement coefficient
(weigthed Kappa: Cohen’s Kw test) showed an improvement in interobserver
agreement (0.71 and 0.84 between A and B; 0.7 and 0.79 between A and C, 0.71
and 0.81 between B and C for conventional US and THI, respectively) (figs.