Abstract
Abstract: :
Purpose: To establish guidelines for orbital imaging by magnetic resonance imaging (MRI) and/or computerized tomography (CT). To apply these guidelines for biopsy–proven orbital tumors at the Jules Stein Eye Institute in a four–year period. Methods: Guidelines for reviewing orbital imaging studies (MRI and/or CT) were established based upon five major characteristics: anatomic location (orbit and vicinity), bone and paranasal sinuses involvement, content, shape, and associated features. In total, 85 features were established by an experienced orbital surgeon and a neuroradiologist. Applying these criteria, imaging studies (CT and/or MRI) of 100 biopsy–proven orbital tumors were evaluated by three physicians: a fellow in orbital surgery, a fellow in neuroradiology, and a second–year ophthalmology resident. Statistical analysis was performed using chi–square test to examine typical features for different diagnoses and different tumors’ groups. Results: One hundred cases of biopsy–proven orbital tumors were evaluated. Common diagnoses included cystic or structural lesions, benign tumors, inflammatory processes, neuronal processes, and fibrous processes; malignant processes including lymphoma and metastasis were less common. Several distinct imaging features were typical of certain diagnoses or groups. Atypical features could be assigned in other cases. Tumor shape, size, relations to orbital vicinity and paranasal sinuses, as well as bony erosion were predictive of a malignant process. Benign lesions were more likely to be smaller in size, circumscribed, and not associated with destructive bone changes. Conclusions: Guidelines for analysis of orbital imaging studies, CT or MRI, have been established and easily implemented for evaluating orbital tumors. They provide a common language for the various specialists, neuroradiologists, ophthalmologists, and others who interpret these studies. A framework for evaluation of orbital imaging studies is useful for teaching, research, and for practical evaluation of patients. We found these guidelines to be reproducible and clinically pertinent. We found good diagnostic accuracy when the typical features that characterize various processes were present, but atypical presentations do occur, therefore a careful diagnostic approach is warranted considering the benefit of imaging studies.
Keywords: imaging/image analysis: clinical • tumors