Liver volume measurement: reason of the difference between in vivo CT-volumetry and intraoperative ex vivo determination and how to cope it.
OBJECTIVE
Volumetric assessment of the liver regularly yields discrepant results between pre- and intraoperatively determined volumes. Nevertheless, the main factor responsible for this discrepancy remains still unclear. The aim of this study was to systematically determine the difference between in vivo CT-volumetry and ex vivo volumetry in a pig animal model.


METHODS
Eleven pigs were studied. Liver density assessment, CT-volumetry and water displacement volumetry was performed after surgical removal of the complete liver. Known possible errors of volume determination like resection or segmentation borders were eliminated in this model. Regression analysis was performed and differences between CT-volumetry and water displacement determined.


RESULTS
Median liver density was 1.07g/ml. Regression analysis showed a high correlation of r(2) = 0.985 between CT-volumetry and water displacement. CT-volumetry was found to be 13% higher than water displacement volumetry (p<0.0001).


CONCLUSIONS
In this study the only relevant factor leading to the difference between in vivo CT-volumetry and ex vivo water displacement volumetry seems to be blood perfusion of the liver. The systematic difference of 13 percent has to be taken in account when dealing with those measures.
Klinik für Strahlenheilkunde, Charite Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany. stefan.niehues@charite.de
Stefan M
SM
Niehues
J K
JK
Unger
M
M
Malinowski
J
J
Neymeyer
B
B
Hamm
M
M
Stockmann
D000818:Animals; D008099:Liver / Q000033:anatomy & histology* / Q000000981:diagnostic imaging*; D009929:Organ Size; D012044:Regression Analysis; D013552:Swine; D013556:Swine, Miniature; D014057:Tomography, X-Ray Computed / Q000379:methods*