High Resolution Magnetic Resonance Imaging With an Orbital Coil as an Alternative to Computed Tomography Scan as the Primary Imaging Modality of Pediatric Orbital Fractures

Abstract

The computed tomography (CT) scan is currently the gold standard in the imaging of orbital fractures. The weak points of this imaging modality, however, include restricted soft tissue depiction as well as the radiation. Both attributes are of particular importance in children because of the high rate of trapdoor fractures and the radiation to the lens. Although magnetic resonance imaging (MRI) is not associated with these drawbacks, it has not been established in the primary diagnosis of pediatric orbital fractures. The aim of our study was to establish the use of MRI with a special orbital coil for the primary diagnosis of pediatric orbital trauma. In our retrospective study, 14 pediatric patients presented to our department with a blunt orbital trauma from 2003 to 2007. Twelve of 14 patients with orbital floor fractures required surgical reconstruction. Until 2004, imaging was carried out by plain x-rays and CT scan for a decision regarding the necessity of surgery. Since introducing the MRI microscopy orbital coil in 2004, CT scans have been replaced by MRI for the primary fracture diagnosis in 8 pediatric cases. Kappa statistics have been applied to assess inter- and intraobserver reliability for CT scans and MRI. This study shows our experiences using MRI in combination with conventional x-rays to determine the operative approach in 2 of the 8 pediatric cases suffering from blunt orbital trauma. The most common causes for pediatric orbital trauma in our collective were accidents. In 8 cases using MRI as the primary imaging modality, depiction of the fracture dislocation and differentiation of the adjacent fatty and muscle tissue was excellent and indication for surgery was distinct. MRI reached a high intra- and inter-rater agreement level (kappa=0.80). MRI combined with a microscopy orbital coil is a valuable alternative to the CT scan in the primary diagnosis of pediatric orbital fractures. Floor fractures, and particularly muscle incarceration, should be diagnosed by high resolution MRI combined with a microscopy coil instead of CT to avoid radiation to the lens and to obtain a better soft tissue depiction.