Magnetic Resonance Imaging and Computed Tomography for the Detection and Characterization of Nonmetallic Intraocular Foreign Bodies

Abstract

Magnetic resonance imaging was superior to CT in IOFB detection. Using these modalities, a set of distinguishing characteristics was established for the identification of the 10 studied materials. We recommend MRI to be part of the evaluation of patients with a suspected IOFB, after CT to rule out metallic IOFBs.

Validation of an Algorithm for Nonmetallic Intraocular Foreign Bodies' Composition Identification Based on Computed Tomography and Magnetic Resonance Imaging

“…In our previous study, 17 10 materials that may be encountered as nonmetallic IOFBs in penetrating and perforating eye injuries were evaluated by CT and MRI. These materials were divided into four groups as follows: plastic {plastic and eyeglass lens (made of the plastic polymer allyl diglycol carbonate, also known as "Columbia Resin #39" [CR-39])}; glass (bottle glass and windshield glass); stone (porcelain [china], gravelstone, concrete, and pencil graphite); and wood (wood and thorn).…”

“…The algorithm for analysis of CT and MR imaging to distinguish IOFB material composition, which had been developed in our previous report. 17 After analysis of CT and T1-MRI scans and T2-MRI scans, the material group can be identified; and after integrating information from GE-MRI scans, the exact material type can be identified. It should be noted that the algorithm is designed for the identification of IOFB composition in cases where both CT and MRI have been performed, and it does not represent a recommended approach for the evaluation of any patient with suspected IOFB.…”

“…Based on this information, an algorithm for the identification of nonmetallic IOFB material has been developed and initially presented in a previous publication. 17 Analysis of CT and MR images of eyes included in the previous study revealed distinguishing characteristics for each of the 10 materials, which were integrated into the algorithm shown in Figure 1. The algorithm integrates information from all scans and consists of three steps: evaluation of the CT scans, then the T1-MRI scans and T2-MRI scans, and at last the GE-MRI scans.…”

“…For the remaining 4 materials (plastic, CR-39, wood, and thorn), images of eyes with 3.0 mm IOFBs were used, because they were barely detectable by CT in smaller sizes. 17 The participants were given a copy of the algorithm and asked to identify the IOFB material by using the four images presented to them in each slide. Before completing the questionnaire, all participants received an explanation of the algorithm and were shown two examples of its use to identify IOFB material.…”

“…[9][10][11][12] Because 60% to 80% of all IOFBs are metallic, 6,13,14 most studies on IOFB identification were focused on metallic IOFB and included only imaging by CT. 8,15,16 In a recent study by our group, a comprehensive comparative analysis on the imaging of nonmetallic IOFBs has been performed. 17 Ten materials that are commonly encountered as nonmetallic IOFBs were imaged by CT and magnetic resonance imaging (MRI) in an ex vivo porcine eye model. Magnetic resonance imaging has been found to be superior to CT in the identification of nonmetallic IOFBs, especially in smaller sizes and when they are made of plastic or wooden materials.…”