Morphological observation of normal lacrimal sac in computed tomography images
Objective To observe the morphology of normal lacrimal sac in the computed tomography images. Methods 50 cases (100 eyes) CT images of normal lacrimal sac were observed in soft tissue window and lung window respectively and divided into four groups ac-cording to the image type and morphology of lacrimal sac: 31 eyes in the lacrimal sac air filling group, 20 eyes in the lacrimal sac half air filling group, 16 eyes in the lacrimal sac semi-closed group and 33 eyes in the lacrimal sac fully closed group. The changes of lacrimal sac morphol-ogy in different groups were compared. Results The imaging features in lacrimal sac air filling group: the coronal lacrimal sac in the soft tis-sue window showed the air density shadow and the shape of the axial lacrimal sac cavity in the lung window was oval. The imaging features in lacrimal sac half air filling group were: the lacrimal sac showed the air density shadow in coronal view of the soft tissue window, the shape of the upper lacrimal sac was oval and the lower lacrimal sac showed curved shape in axial view of the soft tissue window, the shape of the upper lacri-mal sac cavity was oval and the lower lacrimal sac cavity was slit-shaped in axial view of lung window. The imaging features in lacrimal sac semi-closed group were: the upper lacrimal sac showed the air density shadow and the lower lacrimal sac were a soft-tissue density shadow in the coronal view of the soft tissue window, the shape of the upper lacrimal sac lumen was oval and the lower lacrimal sac lumen disappeared in the axial view of lung window. The imaging features in lacrimal sac fully closed group were: the lacrimal sac appeared as a soft tissue density in the soft tissue window and the lacrimal sac cavity disappeared in the lung window. The reason for the changes of the cross-sectional lower lacri-mal sac cavity from oval to slit-shaped or disappearance was the displacement of the lateral wall of the lower lacrimal sac to the nasal side. The expansion of the soft tissue density shadow and the decrease or disappearance of the air density shadow in lacrimal sac were caused by the dis-placement of the orbital soft tissue to the nasal side. The source of the soft tissue density shadow in lacrimal sac CT images was the intraorbital soft tissue. Conclusions The morphology of the normal lacrimal sac may not be fixed but in constantly changing processes. Intraorbital soft tissue pressure can change the morphology of the lower lacrimal sac by pushing the lateral wall of the lower lacrimal sac to the nasal side.
万方数据
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