Abstract
In the collaborative study of the Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED), the validity of ventilation/perfusion lung scans for the diagnosis of acute pulmonary embolism (PE) was shown. Subsequently, the validity of ventilation/perfusion scans, using PIOPED data, was shown in patients with normal chest radiographs, patients with no prior cardiopulmonary disease, in patients with any prior cardiopulmonary disease, and in patients with chronic obstructive pulmonary disease. Stratification of patients according to the presence or absence of prior cardiopulmonary disease was shown to permit an enhanced positive predictive value of PE by applying different criteria to both groups. Further stratification according to clinical assessment further enhanced the ability to assess a positive predictive value of PE.
