A New Method of Functional X-ray Exploration of the Lungs: Photoelectric Stati-Densigraphy

1. Statidensigraphy is a new method of exploration of pulmonary ventilation, operated with a photoelectric cell set in the x-ray field after the rays had been absorbed by the thorax and the lungs. Each cell records the ventilation of one lung. The variations of density between inspiration and expiration are automatically recorded on a photographic film. 2. Simultaneous records of the ventilation of each lung are obtained in normal respiration and forced expiration. In the latter case, the curve is exactly similar to the spirometric tracings. 3. Ventilatory coefficients of similar significance are obtained with both methods, though the respiratory volumes are not directly measured by statidensigraphy. In the latter case, the graph is in linear correspondence with the volumetric variations. The amplitude of the band is proportional to the magnitude of ventilation. A good correlation between spirometry and statidensigraphy was obtained in simultaneous records of normal individuals and patients. 4. The advantage of the method is that no contact with any apparatus hinders spontaneous breathing. The quantity of x-ray necessary for the record amounts to one-fifth the dose used for fluoroscopy. 5. In a few seconds, the percentage of vital capacity of each lung is recorded. The correlation with the far more painstaking and difficult bronchospirometric method is excellent. The emotional, psychologic, and nervous influences on spontaneous respiration are recorded with far greater accuracy than with the spirometry. 6. Local statidensigraphy detects impairments of the ventilation in localized sites such as localized emphysema and air trapping, and makes it possible to establish a topography of the local ventilation for each lung. 7. The clinical results are described in a certain number of patients.