Sensitivity of spiral computed tomography scanning for detecting intraocular foreign bodies.

ABSTRACT

OBJECTIVE: The purpose of this study is to determine whether 3-mm computed tomography (CT) cuts are equivalent to 1-mm CT cuts for detecting small intraocular foreign bodies (IOFBs). DESIGN: Experimental instrument validation study. PARTICIPANTS: Seventy-two porcine eyes were divided into three groups. Each group had 0.5 ml of human blood injected into the vitreous cavity and were surgically implanted with IOFBs. INTERVENTION Each eye was surgically implanted with 0.5-mm metallic, 0.5-mm glass, or 0.5-mm stone IOFBs. Two additional eyes were left without IOFBs to serve as negative controls. MAIN OUTCOME MEASURES: Axial CT images of both 3-mm and 1-mm thickness were obtained and analyzed in masked fashion by two separate neuroradiologists. RESULTS: The sensitivity for detecting 0.5-mm metallic, 0.5-mm glass, and 0.5-mm stone IOFBs with 3-mm CT images was 100%. The sensitivity for detecting 0.5-mm metallic, 0.5-mm glass, and 0.5-mm stone IOFBs with 1-mm CT images was also 100% (confidence interval, 95%; range, 0.88-1.00). Two negative control eyes without IOFBs were also correctly evaluated by the neuroradiologists. CONCLUSIONS: With modern spiral CT scanning, 3-mm cuts are as sensitive as 1-mm cuts for detecting small metallic, glass, and stone IOFBs.