Effect of patient positioning on liver size estimation

Technetium sulfur colloid imaging is widely regarded as a simple, accurate technique for the evaluation of liver size. Although numerous strategies have been proposed for standardizing measurements, none has considered the possibility of a variation depending on whether the patient is imaged erect or recumbent. We imaged several patients in both positions and observed an apparent increase in the vertical length of the liver from supine to upright. We confirmed this by demonstrating a significant increase in the vertical length of both the right and left lobes in a majority of 55 patients imaged in both positions.