VENTILATION-PERFUSION SCINTIGRAPHY IN THE PIOPED STUDY .1. DATA-COLLECTION AND TABULATION

The Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED) study of more than 700 patients is the largest existing study of the accuracy of lung scintigraphy in the diagnosis of acute pulmonary embo lism. Perfusion scans were obtained in all patients and ventilation sc ans in almost all, using standardized techniques. Chest radiographs we re obtained in all patients within 12 hr of the lung scan. Most patien ts underwent pulmonary arteriography. The images were interpreted acco rding to a set of interpretive criteria which remained constant throug hout the trial. A standardized, detailed description of each image set was derived by consensus of teams of two readers blinded to clinical and arteriographic findings. This communication reports the methods us ed to describe and categorize the ventilation-perfusion scintigrams ob tained in patients who were enrolled in the PIOPED study. Scintigraphi c technique is reviewed briefly, probability assessment is described a nd the scan description is reviewed in detail. The form used to descri be the findings on ventilation-perfusion scans is reproduced. Use of t his standardized description permits retrospective evaluation of the P IOPED interpretive criteria. In addition, it represents a rigorous app roach to scan analysis which could facilitate application of formal in terpretive schemes and enhance the reproducibility of lung scan interp retations in the clinical setting.