Comparative study of orbital volumes according to multispiral computed tomography data

BACKGROUND: It is believed that accurate reconstruction of the correct anatomy of the orbital bony walls, restoration of symmetry and volume are necessary for a favorable functional prognosis and elimination of an aesthetic defect. The main problem when estimating orbital volume is its complex anatomy. Scientists use various methods to determine orbital volume, and in reviews comparing various methods for calculating orbital volumes, there is no data on which orbital volumetric method is the most accurate, since each of them has both advantages and disadvantages.

AIM: The aim of this study is the analysis and the comparison of orbital volumes according to multispiral computed tomography data of healthy patients without bone-traumatic changes of orbital walls.

MATERIALS AND METHODS: To measure the volume of orbits, 50 random patients were selected who were examined in the radiology department No. 2 of the University Clinical Hospital No. 1 of the Sechenov University from 2023 to 2024 and who underwent multispiral computed tomography of the facial skeleton for indications unrelated to orbital conditions. Computed tomography data from 25 women and 25 men of different ages (from 18 to 85 years old) were analyzed. A total of 8 groups were formed depending on gender and age: group 1 — women 18–25 years old, group 2 — men 18–25 years old, group 3 — women 26–35 years old, group 4 — men 26–35 years old, group 5 — women 36–50 years old, group 6 — men 36–50 years old, group 7 — women 51 and older, group 8 — men 51 and older. Multispiral computed tomography of the facial skeleton was performed using the Aquilion One 640 CT scanner (Japan) with 0.5 slice thickness in bone and soft tissue windows, to be able to calculate orbital volumes at the workstation, all bone contours of the orbits were marked on each axial slice, starting from the upper wall to the bottom of the orbit with a representation of the orbital volumes in ml.

RESULTS: The difference in the volumes of the right and left orbits of 0.5 ml or more was detected in 5 women out of 25 cases, among men the difference was present in 12 cases out of 25; a difference in volumes of more than 1 ml was noted in 1 woman and 2 men; a difference of more than 1.5 ml was not observed in any study group. The orbital asymmetry coefficient in women ranged from 0 ml to 1.21 ml, in men — from 0.08 ml to 1.19 ml, in women, the average volume of both orbits is less than in men. It was also detected that the volume of orbits increases with age, both in men and women.

CONCLUSIONS: Considering that the majority of patients had differences in orbital volumes of up to 1.0 ml, we agree with studies that indicate the possibility of using a healthy contralateral orbit as a guideline when planning reconstructive surgery. However, for planning surgical treatment, it is recommended to use manual contouring, as this allows the most accurate reproducibility of the bone boundaries of the orbit, although it requires more time than semi- and automatic segmentation. Also, the advantages of the used method for calculating the volumes of orbits in this study include reproducibility on any workstation from different manufacturers, since the method is carried out on a standard tomograph workstation and does not require any additional software.