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A preliminary design study has been carried out for a distributed picture archiving and communication system for the Mallinckrodt Institute of Radiology. The study develops design equations for three layers of a picture network and examines the estimated flow of digital images between a multiplicity of picture sources, picture archives and picture viewing stations. Application of these data to the design equations lead to some preliminary conclusions. One network architecture consistent with these conclusions is discussed.

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Regional ventilation-perfusion ratios have been determined in 12 healthy subjects, 16 patients with pulmonary embolism, and 22 patients with chronic obstructive lung disease. The ventilation-perfusion ratios were determined from xenon-133 ventilation studies and ⁹⁹Tc^m-labeled particle perfusion scans, using either the fractional exchange of air or the relative distribution of tidal volume per unit volume as the numerator of the ratio. A comparison of these two methods showed comparable distributions of regional ventilation-perfusion relationships in the healthy subjects and patients with pulmonary embolism. However, in the patients with chronic obstructive pulmonary disease, the fractional exchange method clearly separated this group of patients from the others.