Comparison of panorama ultrasonography, conventional B-mode ultrasonography, and computed tomography for measuring liver size.

PURPOSE: The objective of the present study is to compare the utility of extended field-of-view ultrasonography and conventional B-mode ultrasonography for determining liver size.

MATERIALS AND

METHODS

The liver size in the medioclavicular line (MCL) was determined in 104 inpatients (females: n = 47; males: n = 57) using both ultrasound methods (Philips HDI 5000). The liver size measured in computed tomography (CT; MX 8000 IDT, Philips) served as the gold standard. The body mass index (BMI), ultrasound scanning conditions, and hepatomegaly identified by CT were evaluated as possible factors affecting the measurement accuracy of the sonographic methods.

RESULTS

The standard deviation of the differences between the measured pairs of values shows less dispersion in B-mode ultrasonography (18.7 mm) than panorama ultrasonography (20.8 mm). The mean value of differences between the measured pairs (bias) in the ultrasonographic methods compared to CT is considerably higher in panorama sonography (15.3 mm; SD = 20.8) than in B-mode ultrasonography (0.27 mm; SD = 18.7). A paired t-test of the mean values shows a significant difference between the ultrasonographic methods (p < 0.0001). In diagnosing or excluding hepatomegaly, B-mode sonography is consistent with CT findings in 84 (80.8 %) of 104 patients and panorama ultrasonography is consistent with CT findings in 77 (74.0 %) of 104 patients. Ultrasonographic methods show moderate agreement with each other (Kappa = 0.4265). Higher BMI and limited scanning conditions lead to an increase in the mean difference of measured pairs of values (bias) as well as to an increase in standard deviation of the differences (dispersion).

CONCLUSION

The determination of liver size in the medioclavicular line using panorama ultrasonography often leads to the false-positive diagnosis of hepatomegaly. Therefore, the method should not be recommended for routine diagnostic scans. In cases of significant hepatomegaly, however, panorama ultrasonography offers superior visualization compared to conventional B-mode ultrasonography.