POSTMORTEM TERMINAL AIRWAY UNIT BRONCHOGRAPHY

Abstract

The postmortem bronchographic method employing a tantalum suspension reported by Gamsu, et al (Invest. Radiol. 6:161–170, 171–175, 1971) offers improved visualization of distal airway units when compared with reconstruction and casting techniques. This study was designed to evaluate alternative bronchographic contrast materials, lung fixation methods, radiographic techniques and histologic preparation methods in the postmortem study of terminal airway units. Air-dried rabbit lungs were prepared by three methods: without fixation, following endobronchial formalin fixation, and after intravascular glutaraldehyde fixation. Barium-gelatin and tantalum suspensions and silver nitrate solutions were evaluated as contrasts for degree of filling and anatomical definition following endobronchial and transpleural injections. Contact stereoradiography of the whole specimen or small tissue blocks was performed on three different fine grain photographic emulsions. Small adjacent blocks of dried lung were then processed by glycol methacrylate and paraffin embedding techniques for histologic correlation. The following preparation sequence proved best: air-drying following intravascular or endobronchial fixation, silver nitrate solution as the contrast agent, whole specimen stereoradiography on fine grain positive film, small tissue block stereomicroradiography on high resolution plates, and glycol methacrylate embedding. Silver nitrate stains the epithelium and thus coats rather than fills the airway lumen. This system provides improved imaging of the two and three dimensional aspects of terminal airway units. Supported in part by James Picker Fellowship in Academic Radiology.