Toyoharu Isawa

Technegas versus krypton-81m gas as an inhalation agent. Comparison of pulmonary distribution at total lung capacity.

&NA; Exactly how the pulmonary distribution of inhaled radioactive gas and Technegas, or ultra‐small aerosol particulates, differs from each other, is still uncertain. The authors compared the distribution of inhaled Kr‐81m gas and Technegas in the lungs at total lung capacity in 13 control subjects with no clinical conditions and 13 patients with various chest diseases. In normal lungs, there was no difference in the distribution ratios in the right and left lungs between inhaled Kr‐81m gas and Technegas. However, there was a significant difference in the lungs of patients with pulmonary disease. Technegas tended to deposit more in the lung bases than did Kr‐81m gas. Despite these statistical differences, they were visually, or qualitatively, similar. From a practical and clinical standpoint, Technegas seems to be useful as an inhalation agent, unless quantitative analyses are required.

Mucociliary clearance in pulmonary vascular disease.

The mucociliary clearance function was studied by radioaerosol inhalation lung cinescintigraphy and its quantification in 8 patients with pulmonary vascular diseases; pulmonary embolism, 5 cases, and right pulmonary artery hypoplasia, pulmonary arteriovenous fistulas, aortitis syndrome, 1 case each. The mucociliary clearance function was found to be well maintained in pulmonary vascular diseases unless ventilation was disturbed. There was no difference in the mucociliary clearance function between pulmonary embolism and other pulmonary vascular diseases.

Incidence of pulmonary embolism in a chest hospital in Japan and importance of preoperative perfusion lung imaging in the diagnosis of postoperative pulmonary embolism.

The incidence of pulmonary embolism was retrospectively studied in a University Chest Institute and its affiliated hospital in Sendai, Japan, whose annual numbers of discharged patients from chest medical wards and lung operations as a whole are about 600 and 400, respectively. Before 1975 there was no documented patient with pulmonary embolism. Since then 70 patients had been clinically suspected of having pulmonary embolism and 31 of the 70 were diagnosed as having pulmonary embolism; 15 without and 16 with surgical operations in the immediate past. Fourteen of the 31 patients required combined perfusion and aerosol inhalation lung imaging for diagnosis. Twelve postoperative patients could be diagnosed as pulmonary embolism by comparing postoperative perfusion lung images taken at the time of suspicion with preoperative perfusion counterparts.Although it is said to be rising, the incidence of pulmonary embolism in a chest hospital still seems to remain low compared with that in western countries. For postoperative patients, comparison with preoperative studies was found very useful in diagnosing postoperative pulmonary embolism. The importance of preoperative perfusion lung imaging cannot be overstressed not only as a preoperative lung function test but as a baseline study to be compared with postoperative perfusion images when pulmonary embolism is clinically suspected in postoperative patients.

Chronic solitary pulmonary nodule due to unsuspected pulmonary infarction from silent pulmonary embolism

Abstract A case of pulmonary embolism showing a longstanding solitary pulmonary nodule is presented. An asymptomatic 57 year‐old man with a solitary nodule in the right lower lobe was referred to our hospital. A pulmonary perfusion‐ventilation scan following a sudden onset of dyspnoea established the diagnosis of recurrent pulmonary embolism. The nodule gradually disappeared after anticoagulant treatment, indicating that the nodule was pulmonary infarction from silent pulmonary embolism. Although the incidence of pulmonary infarction is low in Japan, this case suggests that pulmonary infarction from silent pulmonary embolism should be considered as one important cause of a solitary pulmonary nodule.