Ventilation-Perfusion Lung Scanning and the Diagnosis of Pulmonary Embolism: Improvement of Observer Agreement by the Use of a Lung Segment Reference Chart

Abstract

Summary Objective. To test the hypothesis that the systematic use of a lung segment reference chart can improve the inter- and intra-observer agreement for the interpretation of ventilation-perfusion lung scans. Design. A randomized trial. Study population. Ventilation-perfusion lung scans were obtained in a series of 220 consecutive patients with clinically suspected pulmonary embolism. Intervention. Ventilation-perfusion scans were randomly allocated to one of two series each consisting of 110 ventilation-perfusion lung scans. The first series of lung scans was interpreted according to the routine diagnostic approach, and the second series was interpreted with the mandatory use of a lung segment reference chart on which observed ventilation and perfusion defects were drawn. The two nuclear medicine physicians agreed a priori on the diagnostic criteria of the classification scheme. Measurements. Lung scans were classified as normal, non-high probability, or high probability for pulmonary embolism. The extent of disagreement between the nuclear medicine physicians (inter-observer disagreement) and the lack of internal consistency of each nuclear medicine physician (intra-observer disagreement) was assessed by the percentage disagreement and by kappa statistic. Results. Inter-observer disagreement which was 20% in the first series, decreased significantly in the second series to 7%; P = 0.003. Intra-observer disagreement for the first series was 10% and 22% for the nuclear medicine physicians, respectively. Intra-observer disagreement for the second series of lung scans decreased significantly for one nuclear medicine physician (intra-observer disagreement, 0%; P <0.01), whereas intra-observer disagreement was reduced to 10% for the other nuclear medicine physician (P = 0.09). Conclusion. Inter- and intra-observer disagreement were significantly reduced when two nuclear medicine specialists interpreted ventilation-perfusion lung scans according to the routine diagnostic approach plus the use of a lung segment reference chart. The use of the lung segment reference chart for the interpretation of lung scans is likely to improve the management of patients with clinically suspected pulmonary embolism.

The Risk of Recurrent Venous Thromboembolism in Patients with an Arg506→Gln Mutation in the Gene for Factor V (Factor V Leiden)

“…Lung scanning and pulmonary angiography were performed and interpreted according to standard procedures. 21,22 A diagnosis of fatal pulmonary embolism was based on the findings at autopsy or the opinion of a physician who was not associated with the study. Recurrent venous thromboembolic events were assessed by a committee that was unaware of further clinical details (including factor V Leiden status) of the patients.…”

The value of lung scintigraphy in the diagnosis of pulmonary embolism

“…It is generally accepted that all imaging should be performed in at least six directions (posterior, anterior, two lateral and two oblique views) with perfusion and ventilation images preferably obtained with the patient in identical positions. an anatomical lung segment chart, with the observer drawing in the defects on the chart, is highly recommended [17]. In a series of 220 consecutive patients with clinically suspected pulmonary embolism, and using a classification of normal, high probability and non-diagnostic, this simple method significantly reduced intraobserver variability from 20% to less than 10% and interobserver variability from 20% to 7% [17].…”

Influence of Cardiopulmonary Disease on Resolution of Pulmonary Embolism

“…We found, in a previous study, that the size of initial defects in lung perfusion scan correlated with the size at 6 months and that this could be predicted by means of a regression equation [ 15], The method to quantify the size of the defects in lung scan is relatively simple and repro ducible [16]. A similar score was also used by Palla et al [6], although we introduced the PIOPED criteria [7] to distinguish between large, medium or small defects.…”