Sensitivity of Kr-81m and Xe-127 in evaluating nonembolic pulmonary disease

The relative sensitivities of Kr-81m and Xe-127 in detecting lung ventilation defects was evaluated in 80 patients with nonembolic pulmonary diseases. Krypton-81m ventilation images (500,000 count) were interdigitated with Tc-99m MAA perfusion images; both were compared with Xe-127 images. The distributions of the two gases were also compared on the basis of point-by-point computer analyses. Xenon-127 was found to be more sensitive than Kr-81m in clinical evaluations of scintiphotos--although they were equivalent by computer analyses--in indicating regions of impaired ventilation in patients with obstructive airways disease.