[Estimation of regional pulmonary ventilation using perfusion lung scintigram]

Using perfusion lung scintigram, motion of the regional pulmonary area and lung edge during ventilation was analyzed in 30 patients with various respiratory diseases. Images at maximal inspiration (I) and expiration (E) were obtained after the intravenous injection of 99mTc macroaggregated albumin (222-370 MBq) using a scintillation camera coupling to a small digital computer. Radioactivity in each pixels (E and I) and number of pixels in the both lungs (AE and AI) were calculated from the image of E and I. Changes of the regional pulmonary radioactivity during ventilation were calculated according to an expression as (E-I)/I, and the image of (E-I)/I was obtained too. The image of (E-I)/I consisted of positive and negative components. The image of positive (E-I)/I visualized the motion of the regional pulmonary area, and sum of positive (E-I)/I in the both lungs was correlated with vital capacity (r = 0.83, p less than 0.001). The image of negative (E-I)/I superimposed with the edges of the lung at maximal inspiration and expiration revealed the limits of the motion of the lung edge during ventilation. These results suggest that this technique is useful to estimate the regional pulmonary ventilation and motion of the lung edge.