In 32 patients, 58 angiographically proven pulmonary infarcts were followed for 3 months or longer by serial chest radiography.Complete clearing was seen in 29 (50%) of the infarcts on chest radiography.In the other 29 infarcts that left residual findings, linear scars were identified in 1 4, pleural diaphragmatic adhesions in nine, and localized pleural thickening in six; in all cases the features were diminutive when compared with the original abnormality.Follow-up perfusion lung images at similar time intervals to the chest films were available for 44 infarcts. Seven of these showed complete resolution and the other 37 showed a residual but much smaller perfusion defect. None of the patients had known preexisting pulmonary disease. The frequency of permanent radiographic scarring seemed to be the same at all ages.

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.

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