Abstract

Purpose: To valuate four-quadrant location method in diagnosis and differential diagnosis of the orbital tumor by comparison study combining CT and MRI with pathology.
Materials and methods: Data of 87 patients (44 female and 43 males), aged 1 to 84 years were recruited in this study, including the computed tomography(CT), Magnetic resonance imaging (MRI), and histopathology diagnosis. All orbital tumors were verified radiologically and pathologically in the Hospital of Jinggangshan University from Sep-2008 to April-2016. 49 patients underwent CT scanning (31 Conventional CT and 18 dynamic contrast enhancements CT) and 38 patients underwent MR Imaging (35 dynamic contrast enhancement MRI and 3 conventional MRI). The clinical data were retrieved from the medical record. We classified the orbital region according to four- quadrant and eight-space (FQES) division and traditional muscleconal division with center point of optic nerve.
Results: Among the 87 cases of the orbital tumors, 70 cases (80.45%) were orbital benign tumors and 17 cases (19.54%) were malignant tumors. Regarding the location of the orbit, 41 lesions (47.12%) were in superolateral, 18 lesions (20.68%) were in inferolateral, 16 lesions (18.39%) were in inferomedial, 8 lesions (9.19%) were in superomedial, 3 lesions (3.44%) were in globe, 1 lesion (1.14%) was in optic nerve. The most common tumors are hemangiomas (total 36 cases: 12 in inferolateral, 8 in inferomedial, 9 in superolateral, 7 in superomedial) and 9 cases of pleomorphic adenoma were in superolateral, 9 cases of dermoid cyst ( 7 in superolateral and in 2 inferomedial), 5 cases of inflammatory pseudotumor (4 in superolateral and 1 in inferomedial), 7 cases of lymphoma (3 in superolateral, 2 in inferolateral and 2 in inferomedial ), 3 cases of adenoid cystic carcinoma in superolateral, 3 caese solitary fibrous tumor ( 2 in suprolateral and 1 in inferomedial), 3 cases lipoma (1 in superomedial, 1 in superolateral and 1 in inferolateral), 2 cases choroidal melanoma were in globe, 1 case of metastasis in superolateral, 1 case of meningioma in optic nerve, 1 case of malignant melanoma was in superolateral. The orbital tumors appeared in orbit with mostly regular, oval and rounds shape, well defined margin. The size ranged from 0.8 mm × 4.5 cm to 4.5 cm × 2.0 cm. The CT revealed iso-density in 22, slightly high–density in 15, mixed density in 6, low density in 5 and high density in 1 lesion. Among them, 18 were contrast enhancements. On T1WI image, the MRI revealed low signal intensity in 23 cases, slightly low signal in 4 cases, iso signal intensity in 7 case, high signal intensity in 3 cases, mixed signal intensity in 1 case on T2WI, it revealed high signal intensity in 23 cases, slightly high intensity in 7 cases, low signal intensity in 4 cases, iso signal intensity in 3 cases, mixed signal intensity in 1 case. Among them, 35 contrast enhancement MRI and 3 were non contrast MRI. Benign tumor was diagnosed in 70 patients, of them 34 were male and 36 were female, and the mean age was 45.19 years. Malignant tumor was diagnosed in 17 patients; of them 10 and 7 were male and female respectively, mean age was 57.71 years. There was no significant difference in the age of patients with benign versus malignant tumors (P=0.505). No significant difference was observed in patient’s gender when we compared patients with benign versus malignant tumors (P=0.448). The Right orbit was involved in 36 patients with benign tumor and 11 patients with malignant tumor. Left orbit was involved in 34 patients with benign tumor and 6 patients with malignant tumor. There was no significant difference of side of eye between the benign versus malignant tumors (P=0.324). In comparative study of four quadrant spatial distribution was show significant difference between hemangioma and pleomorphic adenoma (P=0.027) but there was no significant difference seen in other tumors e.g. between lymphoma and inflammatory pseudotumor, between hemangioma and lymphoma, and between pleomorphic adenoma and dermoid cyst. There was also show strongest significant difference between the hemangioma and pleomorphic adenoma (P=0.000) in muscleconal division of the orbit and between hemangioma and lymphoma, (P=0.001) and between hemangioma and dermoid cyst (0.000). A Comparative study of anterior and posterior division of the orbit. There was significant difference between hemangioma and pleomorphic adenoma (P=0.001) and between hemangioma and dermoid cyst (P=0.005). The most significant difference was seen between hemangioma and pleomorphic adenoma in all the comparative studies.
Conclusion: Our study found that the tumor location, margin, shape, radiological findings and pathological results provide important information for diagnosis and differential diagnosis of the orbital tumors. The four-quadrant and eight-space (FQES) division of the orbit in CT and MRI plays an import ant role in determining the location, origin and nature of orbital tumor and lesion, which may have supplementary role to traditional muscleconal division in the assessment of the orbital tumors. The most common neoplasm was orbital cavernous hemangioma and most of orbital tumor s was located in superolateral quadrant region. The role of CT and MRI in detecting the location n and morphology of orbital tumors and to estimate the degree of orbital tumors were well justified by combining the four-quadrant and eight-space (FQES) division with traditional muscleconal division, which is useful for qualitative diagnosis of orbit tumor.

Keywords: Orbital tumors, four quadrant division method, CT, MRI, Pathological diagnosis