CT Three-dimensional Measurement Of Orbital Anatomy And Diagnosis Of Related Diseases

Objectives:(1) To discuss CT three-dimensional imaging of orbital structures and have related measurement in order to give anatomical basis for clinical studies.(2) To review the CT data of orbital diseases and conclude their characteristics of CT signs, which will provide the basis for clinical diagnosis and differential diagnosis.Methods:(1)51subjects, who have received routine orbital CT scan with no significant lesion in orbital, were selected from PACS of our hospital, ages from31to67years old. Three-dimensional imaging of orbits was carried out on the AVIZO software to display the visual three-dimensional structures. On the built-in tools of the software, the related data of orbits were measured, the parameters include:volume of eyeballs, volume of orbit, and the distance from the midpoint in the connection lines of concave points inside and outside orbital bones to eye ball’s front end.(2) From the PACS in the hospital from January in2013to January in2014, this paper is aimed to carry out retrospective analysis of536cases of orbital diseases by choosing those after orbital cavity’s CT examination and pathological or clinical confirmation (297cases for the male,239cases of the female, aging from2to68, average age45.3years).Results:(1) CT3D reconstruction can stereoscopically display orbit, the eye ball and the surrounding’s related anatomic structures.(2) The volumes of left, right eyeball are respectively8887.37±1018.10mm3,8749.32±1094.95mm3; the volumes of soft tissue in the left, right orbital cavities are:17382.29±1635.42mm3,17616.15±1824.26mm3; the distances from the midpoint in the connection lines of concave points inside and outside orbital bones to eye ball’s front end are:the left eye,±1.79mm15.11, right eye15±2.41mm; the distances from optic foramen landmarks to eye balls’ geometric center are:the left eye,37.28±2.68mm, right eye37.08±2.94mm; the angles between the extension line from the eyeballs’ geometric center’s connection line to foramina opticum and the median sagittal plane are:the left eye20.70±2.63degrees, right eye20.90±1.57degrees; the distances from eyeballs’ geometric center to the median sagittal plane are:the right eye30.84±1.80mm:, right eye31.43±1.71mm; the vertical distance from eyeballs’ geometric center to the orbit’s lower edge:the left eye17.21±1.23mm, right eye16.85±1.10mm.(3)536cases of orbital diseases include314cases of trauma (58.58%),91cases of thyroid associated ophthalmopathy (16.98%),63cases of tumor (11.75%),31cases of inflammation (5.78%),17cases of vascular malformation (3.17%),15cases of cyst (2.80%),5cases of congenital diseases (0.93%).(4)In respect of orbital diseases, ages and sex:there are4cases of capillary hemangioma, all in the age less than10;7cases of optic nerve glioma, all in the age from10to30; and14cases of neurilemmoma, in which there are5cases in the age from10to30and8cases in the age from30to50; and91cases of thyroid associated ophthalmopathy, in which there are55cases in the age from30to50and26cases above50years old;15cases of cavernous hemangioma, in which there are12cases in the age from30to50. There are15cases, of varicose vein, in which women account for80%(12/15); and15cases of cavernous hemangioma, in which women account for73.33%(11/15).(5) Five areas of orbital tumors are:26cases of hemangioma tumors,19cases (73.08%) of which are located in the muscle cone area;21cases of neurogenic tumor, with11cases located inside the muscle pyramid (52.38%), with9cases located outside the muscle pyramid (42.86%);4cases of stromal tumor,2cases (50%) of which are located inside the muscle pyramid and2cases (50%) outside;9cases of lacrimal gland tumors, with8cases(88.89%) located outside the muscle pyramid;3cases of metastases, with1case and1case respectively located inside and outside the muscle pyramid, and at the same time1case respectively located inside/outside the muscle pyramid.(6) Main CT signs include:such as bone sag, the thickening sign of EOM, foreign matter inside the orbit, the location of the muscle pyramid behind the eye ball.Conclusion:(1) CT3D reconstruction well displays the orbit and its surrounding anatomic structures to realize observations from single, multi directions and3D measurement.(2) Orbital diseases diverse and complex, the CT imaging features of orbital diseases include progressive enhancement sign, dumbbell sign, double track sign (cuff syndrome), edge enhancement, lacrimal enlargement; and the understanding of CT signs of orbital diseases is helpful to improve the ability for diagnosis of orbital diseases.