Detection and localization of steel intraocular foreign bodies using computed tomography. A comparison of helical and conventional axial scanning.

PURPOSE: To compare the sensitivity and specificity of detection, and accuracy of localization, of small steel intraocular and episcleral foreign bodies, using conventional axial and helical computed tomographic scanning in an experimental model. METHODS: Small steel foreign bodies ranging in size from 0.048 to 0.179 mm3 were placed in intraocular and episcleral locations in eye bank eyes mounted in the orbits of a human skull and scanned using helical and conventional axial techniques. Helical scanning was performed using 1-mm and 3-mm thick sections. Conventional axial scanning was performed using 3-mm thick sections. Images were reviewed by masked observers to determine sensitivity, specificity, and accuracy of localization for each imaging method. RESULTS: Steel foreign bodies as small as 0.048 mm3 were detectable with each scanning protocol. Although the helical scans appeared to provide higher levels of sensitivity compared to conventional axial scanning, the difference in outcome between the scan types was not statistically significant. Sensitivity was dependent on the size of the foreign body and ranged from 45% to 65% for the smaller ones (< 0.06 mm3) to 100% for the larger ones (> 0.06 mm3). Multiplanar reformatting of images was helpful in achieving optimal accuracy. CONCLUSION: In an experimental model of steel intraocular foreign body, helical computed tomographic scanning provided images of high quality similar to that of conventional axial scanning.

Skin test studies on close contacts of leprosy patients in India.

Skin-test studies with a series of tuberculins have been carried out in close contacts of multibacillary (MB) leprosy patients around three leprosy centers in India, and casual contacts of the disease around two centers. The results show that the rate of acquisition of leprosin A positivity is associated with age and the closeness of contact with MB leprosy. At the age of 15 years, the differences between the two types of contact were highly significant (p less than 0.00001). Many responses to leprosin A are directed toward the group iv species-specific, antigens of the leprosy bacillus, and the significance of positivity is discussed in relation to protective immunity from leprosy. The differences from Iran show that positivity to leprosin A is not solely the effect of the degree of contact with the disease, but must also have a genetic or environmental element, the latter being favored. The results from Miraj show that the high levels of tuberculin, scrofulin, and vaccin positivity seen in Fathimanagar, and to a lesser extent in Karigiri, are not a consequence of contact with leprosy. BCG vaccination made little difference to the leprosin A positivity of close contacts of leprosy patients, although it significantly enhanced positivity among casual contacts around Miraj (p less than 0.002). BCG vaccination significantly increased tuberculin positivity in Miraj and Karigri, and in those under 11 years of age in Fathimanagar. It made no difference to the already high level of positivity found in older persons around Fathimanagar.(ABSTRACT TRUNCATED AT 250 WORDS)