title: Rethinking orbital imaging establishing guidelines for interpreting orbital imaging studies and evaluating their predictive value in patients with orbital tumors.
abstract: OBJECTIVE
  To establish guidelines for interpretation of orbital imaging by magnetic resonance imaging (MRI) and/or computed tomography (CT), and to apply these guidelines and examine their predictive value in 131 patients with biopsy-proven orbital tumors.
  
  
  METHODS
  Prospective evaluation of imaging studies.
  
  
  METHODS
  Imaging studies (CT and/or MRI) from 131 cases with biopsy-proven orbital tumors.
  
  
  METHODS
  Guidelines for reviewing orbital imaging studies (MRI and/or CT) were established based on 5 major characteristics: (1) anatomic location, (2) bone and paranasal sinuses involvement, (3) content, (4) shape, and (5) associated features. In total, 84 features were established by an experienced orbital surgeon and a neuroradiologist. Applying these 84 features, imaging studies of 131 biopsy-proven orbital tumors were evaluated by 3 physicians.
  
  
  METHODS
  Imaging features: characteristics, sensitivity, specificity, and positive and negative predictive values in various groups of orbital tumors and kappa values.
  
  
  RESULTS
  One hundred thirty-one cases of biopsy-proven orbital tumors were evaluated. Benign lesions were more likely to be smaller in size, round or oval in shape (29% of all benign tumors, 0% in malignant and inflammatory, P<0.001), and associated with hyperostosis (22% of all benign lesions, P<0.001). They were also more likely to be hyperdense or hypodense on CT imaging (15% and 11%, respectively; P<0.05 in comparison with inflammatory and malignant tumors). Inflammatory processes showed panorbital involvement (23% vs. 3%, and 0% in benign and malignant tumors, respectively; P<0.001). Orbital fat involvement and fat stranding were noticed only in inflammatory lesions (19% and 16%, respectively; P<0.001). None of the features occurred only in malignant tumors, but they tend to involve the anterior orbit more commonly (54% vs. 20%, and 29% in benign and malignant; P = 0.002), and were more likely to show bone erosion (31% vs. 6%, and 16% in benign and inflammatory tumors, respectively; P = 0.004) and molding around orbital structures (29% vs. 3% in benign, and 0% in inflammatory tumors, respectively; P<0.001). Features such as panorbital involvement, orbital fat, frontal sinus opacity, molding around orbital structures, perineural involvement, and fat stranding had specificity of 97% to 100%, but low sensitivity.
  
  
  CONCLUSIONS
  Guidelines for analysis of orbital imaging studies (CT or MRI) are suggested. Based on these guidelines several imaging features showed significantly different occurrences in benign, malignant, and inflammatory processes; although this can help in differential diagnosis, tissue diagnosis may still be required.
authors.affiliation: Jules Stein Eye Institute and Department of Ophthalmology, Los Angeles, California, USA. guybensimon@gmail.com
authors.forename: Guy J
authors.initials: GJ
authors.lastname: Ben Simon
authors.forename: Christine C
authors.initials: CC
authors.lastname: Annunziata
authors.forename: James
authors.initials: J
authors.lastname: Fink
authors.forename: Pablo
authors.initials: P
authors.lastname: Villablanca
authors.forename: John D
authors.initials: JD
authors.lastname: McCann
authors.forename: Robert A
authors.initials: RA
authors.lastname: Goldberg
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001706:Biopsy; D003627:Data Interpretation, Statistical; D005188:False Negative Reactions; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000592:standards*; D008297:Male; D008875:Middle Aged; D009918:Orbital Neoplasms / Q000175:diagnosis*; D017410:Practice Guidelines as Topic / Q000592:standards*; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000592:standards*