HIGH-RESOLUTION CT OF THE LUNG IN ASBESTOS-EXPOSED SUBJECTS - COMPARISON OF LOW-DOSE AND HIGH-DOSE HRCT

The lowest possible mAs settings for high-resolution CT (HRCT) were st udied on 45 individuals with suspected asbestos related lung disease. All patients were investigated with 5 to 6 high-dose HRCT images (120 kVp/160 mA/2 s) at 3-cm intervals. At a selected level 4 additional lo w-dose images were obtained on each patient with lower mAs settings (1 00 mA/2 s, 80 mA/2 s, 60 mA/2 s, 30 mA/2 s). Thirty-seven subjects out of 45 had HRCT lesions compatible with asbestosis. HRCT images obtain ed with as low as 60 mA/2 s settings clearly showed pleural tractions and thickenings, parenchymal bands, honeycombing and subpleural curvil inear shadows, whereas in the evaluation of subpleural short lines and ground glass findings 50 mA/2 s were required. The lowest setting, 30 mA/2 s, was sufficient only in detecting and evaluating pleural tract ions and thickenings. We conclude that 160 mAs yield good quality HRCT images, with substantial decrease of radiation dose, for the evaluati on of asbestos-related lesions.