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The ventilation/perfusion lung scan has been in continuous use for approximately half a century, the same lifetime as Seminars in Nuclear Medicine. Remarkably, the founding Editors-in-Chief have continued to guide the journal over this entire period. In this Feschrift issue celebrating their enormous contribution, we review the history of the lung scan, its highs and lows, the transition from planar to SPECT/CT V/Q scans, and the future that is in store in this age of multimodality functional imaging. We concur with the published view of one of the retiring editors (LMF) that V/Q scintigraphy is indeed alive and well and has a definite future in clinical medicine.

As a consequence of recent studies that have (1) established the role for ventilation-perfusion lung scanning in the diagnosis of pulmonary embolism, (2) clarified the contribution of clinical assessment to the diagnostic utility of lung scans, and (3) established a role for the noninvasive assessment of the lower extremities for deep venous thrombosis in patients suspected of having pulmonary embolism, we can now manage clinically stable patients suspected of pulmonary embolism without need for invasive diagnostic procedures. The various studies establishing this approach are reviewed, and an algorithm is presented that allows for the noninvasive workup of clinically stable patients suspected of having pulmonary embolism.

The importance of measuring regional ventilation is well accepted as a major parameter in the evaluation of regional pulmonary function. Although the perfusion lung scan has been widely used clinically, nuclide ventilatory studies have only recently achieved some degree of popularity. Gamma-densigraphy, a method based on the transmission of a gamma beam through a patient's chest and the measurement of the radiodensity changes with ventilation is described. This technique has the advantages of simplicity, low cost, and patient acceptability. It also yields information reflecting mechanics of respiration not readily obtained from the other commonly used methods for studying regional ventilation. Illustrative cases showing the clinical applications of this method are presented.

The lung scan is an effective, simple, and safe method to evaluate the state of pulmonary arterial perfusion and thus determine the presence or absence of regional ischemia. These attributes have established the lung scan as a screening test in suspected acute pulmonary embolism, despite a significant incidence of false-positive results. The negative scan excludes the possibility of major emboli; however, the perfusion deficits of the positive scan are not specific for embolism.Chronic obstructive pulmonary disease is the principal cause of the nonembolic perfusion deficits that characterize the false-positive scan. Since this condition can be differentiated from acute pulmonary embolism by radionuclide techniques now in the stage of advance clinical investigation, it is anticipated that the lung scan will become even more valuable in the diagnosis, management, and medical understanding of pulmonary disease.