[Regional pulmonary function test--pulmonary nuclear medicine].

Abstract

Pulmonary nuclear medicine has been dominated by techniques that depict the distribution of pulmonary ventilation and perfusion. At present, there are three commercially available methods of performing a ventilation study. One of the methods utilizes xenon-gas 133Xe, one utilizes radioactive krypton gas, 81mKr, and the last is performed with a radioactive aerosol, usually the radio aerosol of 99Tc human serum albumin (HSA). Ventilation studies with 133Xe usually consist of an image taken after inhalation of a single breath, which can be followed by a serial image. After a rebreathing period of 3 to 5 minutes, the tracer (133Xe) is washed out of the lungs. The washout portion of the 133Xe study is the most reliable and sensitive to detect of the slow compartments. Krypton-81m has a very short physical half-life of 13 seconds. Thus, ventilation scans can be obtained in desired projections, and the rapid disappearance of the tracer from lungs will allow ventilation studies to be performed before and after medications and exercise. Radioaerosols also provide a means for investigating regional ventilation. Radioaerosols are small particles, rather than gases, and are deposited in the lung by impaction, sedimentation and random contact. With the recent development of new radiopharmaceuticals and refinement of current imaging techniques, especially quantitative techniques and single-photon emission computed tomography of the lung, pulmonary nuclear medicine has expanded its horizons.