[Evaluation of regional pulmonary 133Xe-gas washout with dynamic SPECT imaging obtained by a triple-headed SPECT system with continuous repetitive rotating acquisition mode].

The clinical potential of the dynamic SPECT in studying pulmonary washout of Xenon-133 (133Xe), using a triple-headed SPECT system (Toshiba GCA 9300A/HG, Japan) with continuous repetitive rotating acquisition mode, was preliminarily investigated in 6 healthy volunteers and 23 patients with various lung diseases. The equilibrium image was initially acquired for 1 min after breathing 133Xe gas (370 MBq) in a closed circuit for 6 min, and subsequently serial 133Xe-washout SPECT images were continuously acquired every 60 sec for 5-6 min. As the ventilation index, the real half time of regional activity was evaluated. The SPECT study demonstrated the gravity-induced gradient on ventilation in the normal subjects. In the various lung diseases, it allowed us to demonstrate visually and quantitatively the dynamic process and three-dimensional distribution of ventilation abnormalities, with or without chest radiographic abnormalities. These results indicate clinical potential of pulmonary dynamic SPECT of 133Xe-washout for elucidating the distribution and nature of ventilation abnormalities in various lung diseases.